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Genetic engineering of parthenocarpic plants
Abstract
Transgenic tobacco and eggplants expressing the coding region of the iaaM gene from Pseudomonas syringae pv. savastanoi, under the control of the regulatory sequences of the ovule-specific DefH9 gene from Antirrhinum majus, showed parthenocarpic fruit development. Expression of the DefH9-iaaM chimeric transgene occurs during flower development in both tobacco and eggplant. Seedless fruits were produced by emasculated flowers. When pollinated, the parthenocarpic plants produced fruits containing seeds. In eggplant, the genetic manipulation allowed fruit set and growth under environmental conditions prohibitive for fruit setting in the untransformed line, which did not set fruit at all. Under normal environmental conditions, production of marketable fruits took place from pollinated and unpollinated transgenic flowers, while flowers of untransformed control plants did produce fruits of marketable size only from fertilized flowers.
... For example, the tryptophan monooxygenase, iaaM, can convert tryptophan into indole-3-acetamide (IAM), which is subsequently converted into IAA. The ovule-specific expression of the iaaM gene using the promoter of the DefH9 gene from Antirrhinum majus enhances auxin biosynthesis, resulting in natural parthenocarpy in plants such as tobacco (Nicotiana tabacum), eggplant (Solanum melongena), cucumber, and strawberry (Fragaria × ananassa) [46][47][48]. Table 1. Genes involved in regulating parthenocarpic fruit formation. ...
... Early fruit growth, normal size and shape [46][47][48] Pad-1 RNAi Normal fruits ...
... Plant parthenocarpy can be promoted through the expression of genes that negatively regulate the initiation of fruit development, such as the Pad-1 and AGL6 genes mentioned above. Conversely, enhancing plant parthenocarpy can also be achieved by the tissue-specific overexpression of genes that initiate fruit development [46,48]. Commonly used overexpression techniques typically result in transgenic products, which face stringent regulations when introduced into the market. ...
Parthenocarpy is an important agricultural trait that not only produces seedless fruits, but also increases the rate of the fruit set under adverse environmental conditions. The study of parthenocarpy in Cucurbitaceae crops has considerable implications for cultivar improvement. This article provides a comprehensive review of relevant studies on the parthenocarpic traits of several major Cucurbitaceae crops and offers a perspective on future developments and research directions.
... Trend for the development of seedless fruits is increasing because seeds are bitter in taste, leathery, or hard textured and may accumulate harmful compounds in many instances [8,9]. According to the consumers demand and better nutritional quality, absence of seeds and seed cavities from many fruits is required [8,10]. Moreover, presence of seeds accelerates the deterioration process of the fruits due to various chemicals present in them [10,11]. ...
... According to the consumers demand and better nutritional quality, absence of seeds and seed cavities from many fruits is required [8,10]. Moreover, presence of seeds accelerates the deterioration process of the fruits due to various chemicals present in them [10,11]. us, seedlessness may also increase the shelf-life of the fruits [12,13]. ...
... Variations of number of seeds per plant and shelf-life among the genotypes of NPT and NST were significantly (p ≤ 0.05) different. Experimental results regarding seeds in NPT fruits were comparable with the studies of [10], where about 10-fold less seeds in parthenocarpic tomato were observed as compared with the control. Reported data described that vitamin C could reduce the shelf-life of the fruits by thinning the pericarp [19]. ...
The aim of the study was to compare the physicochemical parameters, sugar, vitamin C, and phenolic profiles in five genotypes of local indeterminate tunnel tomato hybrid (LITTH) (LITTH-778, LITTH-784, LITTH-786, LITTH-788, and LITTH-790) of natural parthenocarpic tomato (NPT) and normal seeded tomato (NST). Samples were collected from the experimental fields of Ayub Agricultural Research Institute, Faisalabad, Pakistan. Physical parameters (fruit shape, fruit weight, fruit length, fruit width, number of seeds per fruit, and shelf-life) and chemical composition (moisture, ash, crude fat, crude fiber, total carbohydrate, crude protein, and vitamin C) of NPT and NST were analyzed by reported methods. The methanolic extracts of tomato pulp were prepared by shaking and extracts were assayed for antioxidant activity. Sugar contents and phenolic profile of NPT and NST were estimated using HPLC method. Weight and size of NPT were less and smaller than the NST. Moreover, NPT were seedless with longer shelf-life and had more phenolic and flavonoid contents than the NST. HPLC analysis revealed that chlorogenic acid, gallic acid, and p-coumaric acid were major phenolics in methanol (polar solvent) extracts of NST, and caffeic acid, gallic acid, and p-coumaric acid in NPT extract. NPT contained higher concentration of sugar contents, but lower concentration of vitamin C than NST. In 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, NPT fruit extracts showed high scavenging activity with the 50% inhibitory concentration (IC50) value of 22.56 μg/mL compared to NST fruit extracts having IC50 29.49 μg/mL. This study provided useful information for farmers and nutritionists.
... Both areas of research now cover a vast number of agricultural and horticultural crops (Schwabe and Mills, 1981), but often the relationship remained obscure between phytohormonal activity and fruit initiation. In contrast, heritable parthenocarpy that occurs naturally or through induced genetic lesions has provided valuable breakthroughs in crops and several genetic loci involved in fruit initiation are now known (Lin, 1984;Rotino et al., 1997;Vivian-Smith et al., 2001;Yao et al., 2001;Bassel et al., 2008;Marti et al., 2008). Recent advances in understanding fruit initiation and the intrinsic linkage to fertilization are now being completed by genetic analysis and transcriptome profiling. ...
... Furthermore, transcriptional profiling during fruit initiation also shows directionality in phytohormonal responses with auxin preceding gibberellin responses at 12-14 h period post-fertilization (Vriezen et al., 2007). The use of the transgenic DEFH::iaaM construct in a broad range of species (Rotino et al., 1997;Ficcadenti et al., 1999;Mezzetti et al., 2004;Yin et al., 2006) additionally suggests a universal role for auxin in triggering fruit set. Accordingly, auxin-mediated signalling is an early response in the Arabidopsis ovule ( Fig. 4.2). ...
... However, few studies have considered auxin biosynthesis in ovules or developing fruits in detail. Direct proof of the significance for localized auxin biosynthesis in fruit initiation was first obtained by Rotino et al. (1997). In this experiment, the iaaM gene from Pseudomonas syringae pv savastonoi was placed under the control of the placental and ovule-specific promoter DEFH9. ...
Angiosperms have evolved the unique processes of double fertilization and fruit development as key steps of their survival and dispersal strategies. In this chapter, we will examine fertilization and fruit initiation as central restriction points to fruit and seed development. Pollination and fertilization appear essential for fruit initiation, since angiosperm flowers universally enter terminal senescence and abscission phases if pollination is prevented. We review key developmental processes, pathways and genes that were recruited to control and restrict the reproductive growth of the carpel and ovule until fertilization is achieved. Ever since the discovery that exogenous application of phytohormones results in the development of seedless fruit without fertilization (termed parthenocarpy), most research has concentrated on the role of endogenous phytohormones as triggers for fruit initiation after fertilization. We will highlight how uncoupling of fruit initiation from fertilization through mutational studies can further contribute to the understanding of these complex processes. Initial analysis shows that strict local control of auxin signalling, through a transcription factor network, forms one of the decisive and primary events that leads to the hierarchical control over gibberellin metabolism and perception. Testing and challenging these assumptions will provide further knowledge indispensable for controlling fruit set and yield in agriculture.
... Some researchers have previously reported the development of parthenocarpic tomatoes using a tissue-specific promoter and auxin biosynthesis gene combination in a heterologous system 13,15 . In research on a transgene-harboring construct consisting of an iaaM gene (which is involved in the biosynthesis of indole-3-acetic acid) from Pseudomonas syringae pv. ...
... The percentage of parthenocarpic fruit formation was 63% in the iaa9-3 mutant and ranged from 62 to 68% in the Psol80-SlIAA9i lines (4-17, 23, and 25) ( Table 1). The Psol60-SlIAA9i lines showed relatively low parthenocarpic efficiency, measuring 40% (6-10) and 44% (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), compared with the efficiency of other tested lines. When two flowers per flower truss were emasculated, the weight of parthenocarpic fruits from the iaa9-3 mutant was similar to that of fruits from pollinated ovaries of the WT, whereas the weight of the parthenocarpic fruits of the Psol80-SlIAA9i lines was up to 45% of that of the pollinated fruits of the WT. ...
... In unpollinated ovaries, SlIAA9 mRNA was more strongly distributed in the ovule and placenta than in other ovary tissues 39 , implying that the transcript level of SlIAA9 in those tissues is important for parthenocarpic fruit set by SlIAA9 inhibition. Consistent with this interpretation, increased IAA in the placental/ovule tissue was sufficient for induction of parthenocarpic fruit set 14,15 . In the present study, Psol80 and Psol60 also induce the expression of the genes in ovules and placenta (Fig. 2b). ...
Parthenocarpy is the development of an ovary into a seedless fruit without pollination. The ubiquitous downregulation of SlIAA9 induces not only parthenocarpic fruit formation but also an abnormal vegetative phenotype. To make parthenocarpic transgenic tomato plants without unwanted phenotypes, we found two genes, namely, Solyc03g007780 and Solyc02g067760, expressed in ovary tissue but not in vegetative tissues. Solyc03g007780 was expressed in developing ovaries and anthers. Solyc02g067760 mRNA was detected in whole-flower tissues. The promoters of Solyc03g007780 (Psol80) and Solyc02g067760 (Psol60) predominantly induced the expression of genes in the ovule, placenta, endocarp and pollen and in whole-flower tissues, respectively. Psol80/60-SlIAA9i lines, created for SlIAA9-RNA interference controlled by two promoters, successfully formed parthenocarpic fruits without pleiotropic effects in vegetative tissues. Downregulation of SlIAA9, responsible for parthenocarpic fruit formation, was observed in ovules rather than ovaries in the Psol80/60-SlIAA9i lines. Although the weight of parthenocarpic fruits of the Psol80/60-SlIAA9i lines was lower than the weight of pollinated fruits of the wild type (WT), the parthenocarpic fruits presented redder and more saturated colors and higher levels of total soluble solids and titratable acidity than the WT fruits.
... Previous studies have shown that auxin (IAA) has a great influence on the physiological and biochemical processes of higher plants; exogenous IAA can accelerate fruit development and induce drought tolerance [13]. CK has many physiological functions in plants, including stimulating cell division and differentiation, promoting biogenesis and chloroplast differentiation, and preventing leaf senescence [14]. ...
... Exogenous cytokinins can promote the accumulation of endogenous brassinosteroids [79], and BRs have the greatest impact on the growth and metabolism of algae within 24 to 36 h after treatment [80]. It was reported that gibberellin is mainly involved in cell elongation and expansion, but not in cell division [13]. External use of gibberellin can significantly shorten the lag period and activate cell division and growth in the log phase. ...
Phytohormones are a class of small organic molecules that are widely used in higher plants and microalgae as chemical messengers. Phytohormones play a regulatory role in the physiological metabolism of cells, including promoting cell division, increasing stress tolerance, and improving photosynthetic efficiency, and thereby increasing biomass, oil, chlorophyll, and protein content. However, traditional abiotic stress methods for inducing the accumulation of energy storage substances in microalgae, such as high light intensity, high salinity, and heavy metals, will affect the growth of microalgae and will ultimately limit the efficient accumulation of energy storage substances. Therefore, the addition of phytohormones not only helps to reduce production costs but also improves the efficiency of biofuel utilization. However, accurate and sensitive phytohormones determination and analytical methods are the basis for plant hormone research. In this study, the characteristics of phytohormones in microalgae and research progress for regulating the accumulation of energy storage substances in microalgae by exogenous phytohormones, combined with abiotic stress conditions at home and abroad, are summarized. The possible metabolic mechanism of phytohormones in microalgae is discussed, and possible future research directions are put forward, which provide a theoretical basis for the application of phytohormones in microalgae.
... Auxin, gibberellin and cytokinins or mixtures of these hormones have all been proven to be effective in inducing fruit development in the absence of fertilization in several crop species, for instance tomato and eggplants . The role of plant hormones in fruit set and genetic methods for obtaining seedless fruits by manipulating hormones action extensively reviewed by Pandolfini (2009) Biotechnology offers wide range of opportunities and easier ways of obtaining parthenocarpic varieties than conventional breeding (Rotino et al., 1997 andVaroquaux et al., 2000). The processes of seed and fruit development which are intimately connected and synchronized, are controlled by phytohormones . ...
... Transgenic approach, gene silencing by RNA interference (RNAi) and by antisense RNA technology are powerful tools to interfere with the expression of genes. Rotino et al. (1997) reported that, transgenic tobacco and eggplants containing the DefH9-iaaM transgene produce parthenocarpic fruits in the absence of pollination and that seeds are generated inside the fruit following pollination. Parthenocarpy has also been achieved in transgenic tomato plants carrying the DefH9-iaaM construct Pandolfini et al., 2002). ...
... In order to analyse the genetic relationships between eggplant and its relatives, some studies based on molecular marker analysis have been conducted. So far only resistance against lepidopteron insects, using Agrobacterium tumefaciens transformation and parthenocarpic fruit development, has been reported (Rotino, Perri, Zottini, Sommer, & Spena, 1997). ...
... Another interesting approach in genetic engineering is the development of parthenocarpic fruits in brinjal, which can increase consumer's preference. Rotino et al. (1997) introduced iaaM-DefH9 gene in eggplant for parthenocarpy (Table 5). Prabhavathi, Yadav, Kumar, and Rajam (2002) introduced bacterial mannitol-1-phosphodehydrogenase (mtlD) gene into eggplant by A. tumefaciens-mediated transformation. ...
Eggplant (Solanum melongena L.) is a widely cultivated vegetable crop on account of its medicinal and nutritional value and various region-based culinary preparations. The crop is infested by a plethora of biotic and abiotic stresses besides barriers in gene transfer from wild sources. Biotechnological techniques such as micropropagation, in vitro androgenesis, in vitro grafting, somatic hybridisation, marker-assisted breeding and genetic engineering to combat biotic and abiotic stresses such as Agrobacterium mediated genetic transformation for resistance against insects and diseases have been successfully utilised in eggplant improvement programmes. The review shall help eggplant breeders to plan improvement experiments utilising biotechnological techniques in combination with conventional breeding methods. All the tissue culture, molecular and genetic engineering accomplishments with respect to eggplant have been discussed.
... The ovule has a predominant role in this developmental program; the burst of auxin and GA is mainly produced by the young embryo or surrounding tissue (Dorcey et al., 2009;Pattison et al., 2015;Zhang et al., 2016), whereas in the absence of fertilization, ethylene is produced, promoting ovule senescence and flower drop (Carbonell-Bejerano et al., 2011). These facts were drawn in part from the knockdown of the AUXIN RESPONSE FACTOR 7 (ARF7) (de Jong et al., 2009) or DELLA (Marti et al., 2007), or by inducing the expression of auxin (Rotino et al., 1997) or GA biosynthesis enzymes (Garcia-Hurtado et al., 2012). Together with hormones, gene-regulatory networks are recruited to control fruit set. ...
... We show that SlHB15A binds to a DNA motif, matching the consensus binding site previously described for AtHB15 (O'Malley et al., 2016) and another HD-ZIPIII transcription factor (Brandt et al., 2012). We found several auxin genes to be targeted by SlHB15A and differentially expressed; notably, two YUCCA-like flavin monooxygenases, ToFZY2 and ToFZY3, are upregulated in fertilized flowers and in pf1 loss-of-function mutants, consistent with auxinbiosynthesis transgenes leading to parthenocarpy (Rotino et al., 1997). We also found SlARF7 targeted and downregulated in pf1 ovules, also in line with the knockdown of SlARF7 leading to parthenocarpy (de Jong et al., 2009). ...
Fruit set is inhibited by adverse temperatures, with consequences on yield. We isolated a tomato mutant producing fruits under non-permissive hot temperatures and identified the causal gene as SlHB15A, belonging to class-III homeodomain leucine-zipper transcription factors (HD-ZipIII). SlHB15A loss-of-function mutants display aberrant ovule development that mimics transcriptional changes occurring in fertilized ovules and leads to parthenocarpic fruit set under optimal and non-permissive temperatures, in field and glasshouse conditions. Under cold growing condition, SlHB15A is subjected to conditional haploinsufficiency and recessive dosage sensitivity controlled by microRNA 166 (miR166). Knockdown of SlHB15A alleles by miR166 leads to a continuum of aberrant ovules correlating with parthenocarpic fruit set. Consistent with this, plants harboring SlHB15A-miRNA166 resistant allele developed normal ovules and were unable to set parthenocarpic fruit under cold condition. DNA affinity purification sequencing (DAP-seq) and RNAseq analyses revealed SlHB15A is a bifunctional transcription factor, expressing in the ovule integument. SlHB15A binds to the promoters of auxin genes to repress auxin signaling and to ethylene genes to activate their expression. Survey of tomato genetic biodiversity identified pat and pat-1, two historical parthenocarpic mutants, as alleles of SlHB15A. Our finding demonstrates the role of SlHB15A as a sentinel to prevent fruit set in the absence of fertilization and provides a mean to enhance fruiting under extreme temperatures.
... However, exogenous application of plant hormones to get seedless fruits is costly, thus genetic engineering strategies are promoted, aiming at altering hormone biosynthesis or signaling in order to obtain parthenocarpic fruits. Pioneering work, in this domain, targeted the upregulation of the iaaM gene to promote the synthesis of indolacetamide, which can be converted to IAA [67]. The expression of this auxin biosynthesis gene, driven by the promoter of DefH9, a MADS-box gene expressed specifically in ovules, resulted in parthenocarpic fruit development in both tobacco and eggplant [67]. ...
... Pioneering work, in this domain, targeted the upregulation of the iaaM gene to promote the synthesis of indolacetamide, which can be converted to IAA [67]. The expression of this auxin biosynthesis gene, driven by the promoter of DefH9, a MADS-box gene expressed specifically in ovules, resulted in parthenocarpic fruit development in both tobacco and eggplant [67]. Thereafter, the same gene was used to obtain parthenocarpic fruit in several horticultural crops, like tomato and cucumber [68]. ...
With the forecasted fast increase in world population and global climate change, providing sufficient amounts of quality food becomes a major challenge for human society. Seed and fruit crop yield is determined by developmental processes including flower initiation, pollen fertility and fruit set. Fruit set is defined as the transition from flower to young fruit, a key step in the development of sexually reproducing higher plants. Plant hormones have important roles during flower pollination and fertilization, leading to fruit set. Moreover, it is well established that fruit set can be triggered by phytohormones like auxin and gibberellins (GAs), in the absence of fertilization, both hormones being commonly used to produce parthenocarpic fruits and to increase fruit yield. Additionally, a number of studies highlighted the role of ethylene in plant reproductive organ development. The present review integrates current knowledge on the roles of auxin and ethylene in different steps of the fruit set process with a specific emphasis on the interactions between the two hormones. A deeper understanding of the interplay between auxin and ethylene may provide new leads towards designing strategies for a better control of fruit initiation and ultimately yield.
... However, exogenous application of plant hormones to get seedless fruits is costly, thus genetic engineering strategies are promoted, aiming at altering hormone biosynthesis or signaling in order to obtain parthenocarpic fruits. Pioneering work, in this domain, targeted the upregulation of the iaaM gene to promote the synthesis of indolacetamide, which can be converted to IAA [67]. The expression of this auxin biosynthesis gene, driven by the promoter of DefH9, a MADS-box gene expressed specifically in ovules, resulted in parthenocarpic fruit development in both tobacco and eggplant [67]. ...
... Pioneering work, in this domain, targeted the upregulation of the iaaM gene to promote the synthesis of indolacetamide, which can be converted to IAA [67]. The expression of this auxin biosynthesis gene, driven by the promoter of DefH9, a MADS-box gene expressed specifically in ovules, resulted in parthenocarpic fruit development in both tobacco and eggplant [67]. Thereafter, the same gene was used to obtain parthenocarpic fruit in several horticultural crops, like tomato and cucumber [68]. ...
With the forecasted fast increase in world population and global climate change, providing sufficient amounts of quality food becomes a major challenge for human society. Seed and fruit crop yield is determined by developmental processes including flower initiation, pollen fertility and fruit set. Fruit set is defined as the transition from flower to young fruit, a key step in the development of sexually reproducing higher plants. Plant hormones have important roles during flower pollination and fertilization, leading to fruit set. Moreover, it is well established that fruit set can be triggered by phytohormones like auxin and gibberellins (GAs), in the absence of fertilization, both hormones being commonly used to produce parthenocarpic fruits and to increase fruit yield. Additionally, a number of studies highlighted the role of ethylene in plant reproductive organ development. The present review integrates current knowledge on the roles of auxin and ethylene in different steps of the fruit set process with a specific emphasis on the interactions between the two hormones. A deeper understanding of the interplay between auxin and ethylene may provide new leads towards designing strategies for a better control of fruit initiation and ultimately yield.
... In order to analyse the genetic relationships between eggplant and its relatives, some studies based on molecular marker analysis have been conducted. So far only resistance against lepidopteron insects, using Agrobacterium tumefaciens transformation and parthenocarpic fruit development, has been reported (Rotino, Perri, Zottini, Sommer, & Spena, 1997). ...
... Another interesting approach in genetic engineering is the development of parthenocarpic fruits in brinjal, which can increase consumer's preference. Rotino et al. (1997) introduced iaaM-DefH9 gene in eggplant for parthenocarpy (Table 5). Prabhavathi, Yadav, Kumar, and Rajam (2002) introduced bacterial mannitol-1-phosphodehydrogenase (mtlD) gene into eggplant by A. tumefaciens-mediated transformation. ...
Eggplant (Solanum melongena L.) is a widely cultivated vegetable crop on account of its medicinal and nutritional value and various region-based culinary preparations. The crop is infested by a plethora of biotic and abiotic stresses besides barriers in gene transfer from wild sources. Biotechnological techniques such as micropropagation, in vitro androgenesis, in vitro grafting, somatic hybridisation, marker-assisted breeding and genetic engineering to combat biotic and abiotic stresses such as Agrobacterium mediated genetic transformation for resistance against insects and diseases have been successfully utilised in eggplant improvement programmes. The review shall help eggplant breeders to plan improvement experiments utilising biotechnological techniques in combination with conventional breeding methods. All the tissue culture, molecular and genetic engineering accomplishments with respect to eggplant have been discussed.
... The high number of nonfertilized seeds observed for both cultivars in netting treatments may not indicate high efficiency for the dissemination of pollen by wind, but fruit set was clearly achievable with low seed content. Facultative parthenocarpy was inducible under conditions adverse for pollination and fertilization [19,49]. The existence of naturally occurring parthenocarpic 'Cox's Orange Pippin' fruit tended to be highest when the number of seeded fruit was low, indicating that seedless fruit may be at a competitive disadvantage for retention [24]. ...
... Low maximum temperatures (i.e., within the range observed in the present experimental sites) may not have markedly shortened the effective pollination period, since retarded growth of pollen tubes would be accompanied by delayed senescence of ovules [50]. The effect of netting on seed production could have additionally been due to the change in auxin activity [49] though we do not have data to support this contention. High auxin levels in fruiting spurs the year following a seeded crop of 'd'Anjou' pear were correlated with set of seedless fruit [20]. ...
Thinning is a critical but challenging practice in apple production, especially for organic producers. The objective of this experiment was to determine if exclusion netting, used to manage insect pests and stress, could reduce fruit set and thinning requirements of ‘Gala’ and ‘Honeycrisp’ apple trees in Michigan and Washington, U.S.A., respectively. Nets were closed around whole canopies at different timings based on a predetermined percentage of open flowers. In 2017 and 2018, netted trees set a full commercial crop regardless of percentage of open bloom at the time of netting, including prebloom enclosures. Fruit set and yield of netted ‘Honeycrisp’ trees were significantly lower than non-netted, nonthinned controls but similar to non-netted hand-thinned controls. ‘Gala’ fruit set and yield did not differ among treatments. Exclusion netting markedly reduced the number of mature seeds and increased the number of nonfertilized seeds in both cultivars. Pollinator exclusion to ‘Gala’ in a frost year increased parthenocarpic fruit set two-fold compared to non-netted trees. Fruit size, shape, and quality attributes of ‘Gala’ were were similar among treatments, but ‘Honeycrisp’ fruit were significantly smaller than hand-thinned, non-netted controls. Netting may constitute an alternative, viable strategy to manage fruit set but requires testing on different cultivars.
... Parthenocarpy has commercial value in some plant species for several reasons. First, seedlessness is a desirable characteristic for some fruits and vegetables (Rotino et al. 1997;Carmi et al. 2003). Second, parthenocarpy can positively affect stability of fruit formation and yield under nonoptimal pollination conditions (Lipari and Paratore 1987;Yao et al. 2001;Liu et al. 2018). ...
... Parthenocarpic plants have also been produced using de novo genetic variation created via engineering or editing of genes associated with hormone synthesis, signaling, transport, and response (reviewed by Dhatt and Kaur 2016). For example, overexpression of the bacterial auxin biosynthesis gene iaaM under the control of a tissue-specific promoter resulted in the production of parthenocarpic fruit in tobacco, eggplant, tomato, strawberry, and raspberry (Rotino et al. 1997;Pandolfini et al. 2002). Silencing of genes coding for GA2ox enzymes, leading to an increased level of active gibberellic acids, produced parthenocarpic fruit formation in tomato (Martinez-Bello et al. 2015). ...
... Therefore, this male sterility makes a significant contribution to F 1 seed production in that seed contamination by selfing does not occur at all. Rotino et al. (1997) developed an excellent parthenocarpic eggplant by genetic engineering. Yoshida et al. (1998) found the useful parthenocarpy possessed by European eggplant cultivars. ...
In order to develop a male sterile eggplant (Solanum melongena L.), cytoplasm substitution lines of eggplant were produced by continuous backcrossing using Solanum aethiopicum L. Gilo Group (i.e. S. gilo Raddi.) as cytoplasm donor and eggplant as nucleus donor. In the interspecific F1 hybrids between S. aethiopicum Gilo Group and eggplant ‘Uttara’ and ‘Senryo nigo,’ only the F1, whose paternal parent is ‘Senryo nigo’ was able to make BC1. After the BC1, ‘Uttara’ was used as a recurrent pollen parent to grow up to BC5. The pollen staining ability decreased as the backcrossing generation progressed and completely disappeared in the BC4 and BC5. The highest percentage of fruit set was observed in the BC5 with about 69%. The number of seeds per fruit was observed in BC4 and BC5 was relatively high. These indicate that the cytoplasm of S. aethiopicum Gilo Group has no notable negative effect on the seed fertility of S. melongena. Analyses of chloroplast DNA and mitochondrial DNA of the BC5 confirmed that all backcross progenies had the cytoplasm from S. aethiopicum Gilo Group. A new male sterile line of eggplant could be developed by utilizing the cytoplasm of S. aethiopicum Gilo Group.
... The signals for fruit set include auxin and other hormones produced by the embryo and/ or endosperm within the developing seeds (Hu et al. 2008;Dorcey et al. 2009;De Jong, Wolters-Arts, et al. 2009;Serrani et al. 2010;Figueiredo and Köhler 2018). Parthenocarpic fruits form as a result of altered auxin response (Abad and Monteiro 1989;Vivian-smith and Koltunow 1999;Kang et al. 2013;Joldersma and Liu 2018;Fenn and Giovannoni 2021;Sharif et al. 2022); when auxin is overproduced in ovaries of transgenic plants (Rotino et al. 1997(Rotino et al. , 2005Acciarri et al. 2002;Mezzetti et al. 2004;Pandolfini et al. 2007); in response to inhibition of auxin transport (Serrani et al. 2010;Mounet et al. 2012;Pattison and Catalá 2012); or in transgenic plants with perturbed auxin physiology (Carmi et al. 2003;Molesini et al. 2009;Kim et al. 2020). Thus, local alteration of auxin response is sufficient to promote fruit development in plants with diverse fruit biology. ...
Fruit formation depends on successful fertilization and is highly sensitive to weather fluctuations that affect pollination. Auxin promotes fruit initiation and growth following fertilization. Class A auxin response factors (Class A ARFs) repress transcription in the absence of auxin and activate transcription in its presence. Here we explore how multiple members of the ARF family regulate fruit set and fruit growth in tomato (Solanum lycopersicum) and Arabidopsis thaliana, and test whether reduction of SlARF activity improves yield stability in fluctuating temperatures. We found that several tomato Slarf mutant combinations produced seedless parthenocarpic fruits, most notably mutants deficient in SlARF8A and SlARF8B genes. Arabidopsis Atarf8 mutants deficient in the orthologous gene had less complete parthenocarpy than did tomato Slarf8a Slarf8b mutants. Conversely, Atarf6 Atarf8 double mutants had reduced fruit growth after fertilization. AtARF6 and AtARF8 likely switch from repression to activation of fruit growth in response to a fertilization-induced auxin increase in gynoecia. Tomato plants with reduced SlARF8A and SlARF8B gene dosage had substantially higher yield than the wild type under controlled or ambient hot and cold growth conditions. In field trials, partial reduction in the SlARF8 dose increased yield under extreme temperature with minimal pleiotropic effects. The stable yield of the mutant plants resulted from a combination of early onset of fruit set, more fruit-bearing branches and more flowers setting fruits. Thus, ARF8 proteins mediate the control of fruit set, and relieving this control with Slarf8 mutations may be utilized in breeding to increase yield stability in tomato and other crops.
... The primary advantage of parthenocarpy is that fruit set and growth are not impeded by adverse environmental conditions, so as to further ensure the stability of fruit productivity [2]. Therefore, the trait of parthenocarpy can be of great value to consumers, the processing industries, and breeding companies [1,2,4]. ...
Kiwifruit an important horticultural crop that is widely cultivated and is known as the king of fruits. Recently, a new seedless kiwifruit cultivar, ‘Chengxiang’ (Actinidia arguta), was discovered by field transplantation. It exhibited distinguishable characteristics such as parthenocarpy, and a unique flavor and appearance when compared to other cultivated type. Flavonoids are known to play an important role in fertility and parthenocarpy in plants. However, the genes responsible for flavonoid biosynthesis in seedless kiwifruit remain largely unknown. Especially, chalcone synthase (CHS), as a key enzyme catalyzing the first committed step in the flavonoid pathway, remains a mystery. In this study, we combined a full-length transcriptome survey by PacBio single-molecule real-time (SMRT) sequencing, CHS gene family analysis, and analysis of the gene expression involved in flavonoid pathways to further enhance the understanding of parthenocarpy. Based on SMRT, we obtained 80,615 high-quality full-length consensus transcripts. In total, 52,406 (90.79%) transcripts were functionally annotated, and more than 80% of the transcripts were longer than 1Kb. Among them, 39,117 (74.64%) transcripts were assigned to GO terms, the majority of which were associated with the cell (19,089, 48.80%) and metabolic process (19,859, 50.77%). Furthermore, 25,289 (48.26%) transcripts were mapped into 129 KEGG pathways. We identified the majority of putative genes as being involved in the flavonoid biosynthesis pathway, including 14 key enzyme gene families, such as CHS, chalcone isomerase (CHI), flavonol synthase (FLS), and so on. Moreover, we also identified 13 CHS genes and characterized the CHS gene family in seedless kiwifruit. We further evaluated the expression pattern of 10 flavonoid-related key enzyme genes in flowers using quantitative real-time PCR. This is the first time that the full-length transcriptome have been studied in seedless kiwifruit, and the findings enhance our understanding the molecular mechanisms of parthenocarpy.
... Fruits at this stage lose their commercial value as they are characterized by a loss of color, and above all by presence of mature seeds and spoilage of the flesh texture. Eggplant fruits are therefore normally harvested well before the ripe stage when the colored cultivars have high anthocyanin levels still reflected in strong purple, lilac or black pigmentations and seeds are barely detectable in the pulp, if at all (Rotino et al., 1997). ...
Eggplant fruits are normally harvested and marketed when they reach the commercial maturity, that precedes the physiological ripening when dramatic changes in taste, composition and peel color take place. The biochemical changes in fruit peel across the developmental stages, characterized also by a sizeable decrement of anthocyanins, were studied in four eggplant genotypes differing for fruit pigmentation. HPLC-DAD, HPLC-ESI-MS and NMR analyses identified naringenin chalcone and naringenin 7-O-glucoside as the main phenolic compounds in extracts from the physiological ripe stage, along with compounds tentatively identified as glycosylated naringenin chalcone, naringenin and kaempferol. On average, the levels of anthocyanins, responsible for the peel pigmentation, dropped by 75% during development, while, surprisingly, the level of total phenols showed a slight decrease of 16%, with a final concentration of more than 1000 mg/100g dw. RT-qPCR expression profiling of nine genes coding for enzymes putatively acting at different steps of the involved pathways showed modulation mostly consistent with the observed changes in phenolic composition, with a remarkable decrease in the activity of flavonol reductase and an increase in flavonol synthase during berry development. Antioxidant activity monitored by peroxyl scavenging was similar at all developmental stages while Fremy's analysis evidenced a slight decrement at full physiological ripening. These results are valuable to address the improvement of eggplant commercial fruit quality and the valorization of unmarketable physiological ripe fruits, especially for the newly accumulation of the health-promoting compounds chalcones and flavanones.
... Phytohormones are thought to be triggers induced by fertilization. Many strategies to producing virgin fruit include the exogenous application or overproduction of plant hormones, particularly auxin and gibberellins (GAs) [4][5][6], as well as the mutation of specific genes in these two plant hormone signaling pathways [7,8]. Auxin partially acts upstream of GAs in inducing fruit set [9]. ...
Background
Parthenocarpy results in traits attractive to both consumers and breeders, and it overcomes the obstacle of self-incompatibility in the fruit set of horticultural crops, including pear ( Pyrus bretshneider ). However, there is limited knowledge regarding the genetic and molecular mechanisms that regulate parthenogenesis.
Results
Here, in a transcriptional comparison between pollination-dependent fruit and GA 4 -induced parthenocarpy, PbCYP78A6 was identified and proposed as a candidate gene involved in parthenocarpy. PbCYP78A6 is similar to Arabidopsis thaliana CYP78A6 and highly expressed in pear hypanthia. The increased PbCYP78A6 expression, as assessed by RT-qPCR, was induced by pollination and GA 4 exposure. The ectopic overexpression of PbCYP78A6 contributed to parthenocarpic fruit production in tomato. The PbCYP78A6 expression coincided with fertilized and parthenocarpic fruitlets development and the expression of fruit development-related genes as assessed by cytological observations and RT-qPCR, respectively. PbCYP78A6 RNA interference and overexpression in pear calli revealed that the gene is an upstream regulator of specific fruit development-related genes in pear.
Conclusions
Our findings indicate that PbCYP78A6 plays a critical role in fruit formation and provide insights into controlling parthenocarpy.
... Phytohormones are thought to be triggers induced by fertilization. Many strategies to produced virgin fruit include the exogenous application or overproduction of plant hormones, particularly auxins and gibberellins (GAs) [4][5][6], as well as the mutation of speci c genes in these two plant hormone signaling pathways [7][8]. Auxins partially act upstream of GAs in inducing fruit set [9]. ...
Background: Parthenocarpy results in traits attractive to both consumers and breeders, and it overcomes the obstacle of self-incompatibility in the fruit set of horticultural crops, including pear (Pyrus bretshneider). However, there is limited knowledge regarding the genetic and molecular mechanisms that regulate parthenogenesis.
Results: Here, in a transcriptional comparison between pollination-dependent and GA4-induced parthenocarpy, PbCYP78A6 was identified and proposed as a candidate gene involved in parthenocarpy. PbCYP78A6 is similar to Arabidopsis thaliana CYP78A6 and is highly expressed in pear hypanthia. The increased PbCYP78A6 expression, as assessed by RT-qPCR, was induced by pollination and GA4 exposure. The ectopic overexpression of PbCYP78A6 contributed to parthenocarpic fruit production in tomato. The PbCYP78A6 expression coincided with fertilized and parthenocarpic fruitlet development and the expression of fruit development-related genes as assessed by cytological observations and RT-qPCR, respectively. PbCYP78A6 RNA interference and overexpression revealed that the gene is an upstream regulator of fruit development-related genes in pear.
Conclusions: Our findings indicate that PbCYP78A6 plays a critical role in cell proliferation and provide insights into controlling parthenocarpy.
... The iaaM gene driven by the DefH9 promoter has been introduced to transgenic eggplant to enhance auxin biosynthesis in the ovule and placenta. As a result, parthenocarpic seedless fruits were produced by emasculated flowers [119]. When the flowers were allowed to pollinate, a normal fruit setting was observed that contained seeds. ...
Eggplant (Solanum melongena) is the third most important vegetable in Asia and of considerable importance in the Mediterranean belt. Although global eggplant production has been increasing in recent years, productivity is limited due to insects, diseases, and abiotic stresses. Genetic engineering offers new traits to eggplant, such as seedless parthenocarpic fruits, varieties adapted to extreme climatic events (i.e., sub- or supra-optimal temperatures), transcription factor regulation, overexpressing osmolytes, antimicrobial peptides, Bacillusthuringiensis (Bt) endotoxins, etc. Such traits either do not occur naturally in eggplant or are difficult to incorporate by conventional breeding. With controversies, Bt-expressing eggplant varieties resistant to eggplant fruit and shoot borers have already been adopted for commercial cultivation in Bangladesh. However, to maximize the benefits of transgenic technology, future studies should emphasize testing transgenic plants under conditions that mimic field conditions and focus on the plant’s reproductive stage. In addition, the availability of the whole genome sequence, along with an efficient in vitro regeneration system and suitable morphological features, would make the eggplant an alternative model plant in which to study different aspects of plant biology in the near future.
... It is widely accepted that auxin synthesized by fertilized achenes drives fleshy fruit development and ripening, e.g., in strawberries [37][38][39], and that genetic boosting of auxin formation in ovules through the tissue-specific expression of the iaaM gene promotes parthenocarpy in tobacco, eggplant, and tomato [40][41][42]. The role of auxin in regulating the development and maturation of dry dehiscent seeds, such as in the model plant Arabidopsis, is still less well understood, although great progress has been made over the past few years [43][44][45]. ...
The major auxin, indole-3-acetic acid (IAA), is associated with a plethora of growth and developmental processes including embryo development, expansion growth, cambial activity, and the induction of lateral root growth. Accumulation of the auxin precursor indole-3-acetamide (IAM) induces stress related processes by stimulating abscisic acid (ABA) biosynthesis. How IAM signaling is controlled is, at present, unclear. Here, we characterize the ami1 rooty double mutant, that we initially generated to study the metabolic and phenotypic consequences of a simultaneous genetic blockade of the indole glucosinolate and IAM pathways in Arabidopsis thaliana. Our mass spectrometric analyses of the mutant revealed that the combination of the two mutations is not sufficient to fully prevent the conversion of IAM to IAA. The detected strong accumulation of IAM was, however, recognized to substantially impair seed development. We further show by genome-wide expression studies that the double mutant is broadly affected in its translational capacity, and that a small number of plant growth regulating transcriptional circuits are repressed by the high IAM content in the seed. In accordance with the previously described growth reduction in response to elevated IAM levels, our data support the hypothesis that IAM is a growth repressing counterpart to IAA.
... In most fruit crops, seedlessness is a desirable trait, both for fresh consumption and in processed fruits. A wide variety of techniques for the production of seedless fruits, such as treatment with phytohormones or chemical compounds, utilization/breeding of aneuploidy/polyploidy or genetically seedless cultivars, have been developed (Rotino et al., 1997;Varoquaux et al., 2000). Representative practices are gibberellin treatment in table grapes (Weaver and Pool, 1965;Kimura et al., 1996), utilization of triploids in banana or water-Received; September 14, 2020. ...
Noninvasive diagnosis of internal traits in fruit crops is a high unmet need; however it generally requires time, costs, and special methods or facilities. Recent progress in deep neural network (or deep learning) techniques would allow easy, but highly accurate diagnosis with single RGB images, and the latest applications enable visualization of “the reasons for each diagnosis” by backpropagation of neural networks. Here, we propose an application of deep learning for image diagnosis on the classification of internal fruit traits, in this case seedlessness, in persimmon fruit (Diospyros kaki). We examined the classification of seedlessness in persimmon fruit by using four convolutional neural networks (CNN) models with various layer structures. With only 599 pictures of ‘Fuyu’ persimmon fruit from the fruit apex side, the neural networks successfully made a binary classification of seedless and seeded fruits with up to 85% accuracy. Among the four CNN models, the VGG16 model with the simplest layer structure showed the highest classification accuracy of 89%. Prediction values for the binary classification of seeded fruits were significantly increased in proportion to seed numbers in all four CNN models. Furthermore, explainable AI methods, such as Gradient-weighted Class Activation Mapping (Grad-CAM) and Guided Grad-CAM, allowed visualization of the parts and patterns contributing to the diagnosis. The results indicated that finer positions surrounding the apex, which correspond to hypothetical bulges derived from seeds, are an index for seeded fruits. These results suggest the novel potential of deep learning for noninvasive diagnosis of fruit internal traits using simple RGB images and also provide novel insights into previously unrecognized features of seeded/seedless fruits.
... It is widely accepted that auxin synthesized by fertilized achenes drives fleshy fruit development and ripening, e.g. in strawberries [37][38][39], and that genetic boosting of auxin formation in ovules through the tissue-specific expression of the iaaM gene promotes parthenocarpy in tobacco, eggplant, and tomato [40][41][42]. The role of auxin in regulating seed development in dry dehiscent fruits, such as in the model plant Arabidopsis, is still less well understood, although great progress has been made over the past years [43][44][45]. ...
The major auxin, indole-3-acetic acid (IAA), is associated with a plethora of growth and developmental processes including embryo development, expansion growth, cambial activity, and the induction of lateral root growth. Accumulation of the auxin precursor indole-3-acetamide (IAM) induces stress related processes by stimulating abscisic acid (ABA) biosynthesis. How IAM signaling is controlled is, at present, unclear. Here, we characterize an ami1/rooty double mutant, that we initially generated to study the metabolic and phenotypic consequences of a genetic blockade of the indole glucosinolate and IAM pathways in Arabidopsis thaliana. Our mass spectrometric analyses of the mutant revealed that the combination of the two mutations is not sufficient to fully prevent the conversion of IAM to IAA. The detected strong accumulation of IAM was, however, recognized to substantially impair seed development. We further show by genome-wide expression studies that the double mutant is broadly affected in its translational capacity, and that a small number of cell proliferation and plant growth regulating transcriptional circuits are repressed by the high IAM content in the seed. In accordance with the previously described growth reduction in response to elevated IAM levels, our data support the hypothesis that IAM is a growth repressing counterpart to IAA.
... Auxin response redistribution was demonstrated in tomato fertilized ovules (Pattison and Catalá, 2012). Exogenous application of auxin on ovaries and its ectopic production in ovules, as well as alteration of its content, sensitivity, perception, transport, and signaling, resulted in seedless (parthenocarpic) fruit production (Rotino et al., 1997;Serrani et al., 2008Serrani et al., , 2010Goetz et al., 2007;Joldersma and Liu, 2018). In tomato, auxin-induced parthenocarpy was shown to depend on the activation of gibberellic acid (GA) biosynthesis (Serrani et al., 2008;de Jong et al., 2009). ...
Fruit set is established during and soon after fertilization of the ovules inside the quiescent ovary, but the signaling pathways involved remain obscure. The tomato (Solanum lycopersicum) CRISPR loss-of-function mutant of the transcription factor gene AGAMOUS-like6 (SlAGL6; slagl6CR-sg1) is capable of fertilization-independent setting of normal, yet seedless (parthenocarpic), fruit. To gain insight into the mechanism of fleshy fruit set, in this study, we investigated how slagl6CR-sg1 uncouples fruit set from fertilization. We found that mutant ovules were enlarged due to integument over-proliferation and failed to differentiate an endothelium, the integument’s innermost layer, upon maturation. A causal relationship between slagl6 loss-of-function and these abnormal phenotypes is inferred from the observation that SlAGL6 is predominantly expressed in the immature ovule integument, and upon ovule maturation, its expression shifts to the endothelium. The transcriptome of unfertilized mutant ovules profoundly differs from that of wild-type and exhibits substantial overlap with the transcriptomes of fertilized ovules sporophytic tissues. One prominent upregulated gene was the fertilization-induced cytochrome P450 cell proliferation regulator SlKLUH. Indeed, ectopic overexpression of SlKLUH stimulated both integument growth in unfertilized ovules and parthenocarpy, suggesting that its suppression by SlAGL6 is paramount for preventing fertilization-independent fruit set. Taken together, our study informs on the transcriptional programs that are regulated by SlAGL6 and demonstrates that it acts from within the ovule integument to inhibit ovary growth beyond anthesis. That by suppressing components of the fertilization-induced ovule reprogramming underlying fruit set.
... Besides acting on components of the auxin signaling pathway, parthenocarpic fruit development can be achieved in tomato by increasing the content of IAA in the ovary [34][35][36][37]. Recently, a parthenocarpic eggplant mutant, named pad-1, was shown to accumulate a high level of IAA in the ovaries [38]. ...
Fruit set is the earliest phase of fruit growth and represents the onset of ovary growth after successful fertilization. In parthenocarpy, fruit formation is less affected by environmental factors because it occurs in the absence of pollination and fertilization, making parthenocarpy a highly desired agronomic trait. Elucidating the genetic program controlling parthenocarpy, and more generally fruit set, may have important implications in agriculture, considering the need for crops to be adaptable to climate changes. Several phytohormones play an important role in the transition from flower to fruit. Further complexity emerges from functional analysis of floral homeotic genes. Some homeotic MADS-box genes are implicated in fruit growth and development, displaying an expression pattern commonly observed for ovary growth repressors. Here, we provide an overview of recent discoveries on the molecular regulatory gene network underlying fruit set in tomato, the model organism for fleshy fruit development due to the many genetic and genomic resources available. We describe how the genetic modification of components of this network can cause parthenocarpy, discussing the contribution of hormonal signals and MADS-box transcription factors.
... Hence, efforts have been made to engineer parthenocary either by increasing the auxin production or sensitivity of the ovary to auxins. Expression of iaaM gene driven by the ovule specific promoter DefH9 has been shown to confer parthenocarpy to transgenic tomato (Ficcadenti et al., 1999) and eggplant ( Fig. 1) (Rotino et al., 1997), and also resulted in high yield and fruit quality in eggplant (Donzella et al., 2000). Recently, the Agrobacterium rhizogenes-derived gene rolB has been used as an alternative approach for the induction of parthenocarpy in tomato. ...
Vegetables play an important role in human nutrition and health. Cultivation of vegetable crops is an integral part of the agricultural economy of many developing countries. Vegetable crop productivity and quality are seriously affected by several biotic and abiotic stresses, which destabilize rural economies in many countries. Moreover, absence of proper post-harvest storage and processing facilities leads to qualitative and quantitative losses. In the past four decades, conventional breeding has contributed significantly for the improvement of vegetable yields, quality, post-harvest life, and resistance to biotic and abiotic stresses. However, there are many constraints in conventional breeding, which can only be overcome by advancements made in modern biology. In the last decade various traits such as biotic stress resistance, quality and storage life have been successfully engineered into vegetable crops and some of them have been commercialized. In recent years significant progress has been made to manipulate vegetable crops for abiotic stress tolerance, quality improvement and pharmaceutical and industrial applications. Although the progress in commercialization of transgenic vegetable crops has been relatively slow, transgenic vegetables engineered for nutraceutical and pharmaceutical use will contribute significantly to the value added agriculture in near future.
... In addition, changes in auxin biosynthesis and signaling pathways have been shown to induce parthenocarpic fruit set and fruit development. In tobacco and eggplant, the overexpression of the ovulespecific auxin biosynthesis gene DefH9::tryptophan 2monooxygenase (iaaM) results in parthenocarpy 14 . When overexpressed in tomato, the auxin receptor transport inhibitor response (TIR) is responsible for parthenocarpic fruit 15 . ...
Parthenocarpy is a valuable trait in self-incompatible plants, such as pear. N-(2-chloro-4-pyridyl)-N’-phenylurea (CPPU), a synthetic cytokinin analog, can induce parthenocarpy in pear (Pyrus spp.), but the mechanism of induction is unclear. To investigate the role of gibberellin in CPPU-induced parthenocarpy in pear, CPPU supplemented with paclobutrazol (PAC) was sprayed onto ‘Dangshansu’ pear. We found that the fruit set rate of pear treated with CPPU supplemented with PAC was identical to that in a CPPU-alone treatment group. In regard to cell development, CPPU mainly promoted hypanthium cell division and expansion, and PAC application had no influence on CPPU-induced cell development. RNA sequencing revealed that gibberellin 20 oxidase and gibberellin 3 oxidase genes were not differentially expressed following CPPU treatment. According to the analysis of fruit phytohormone content, the CPPU treatments did not induce gibberellin biosynthesis. These results suggest that CPPU-induced parthenocarpy may be gibberellin independent in ‘Dangshansu’ pear. After CPPU treatment, the indole acetic acid (IAA) content in fruit was significantly increased, and the abscisic acid (ABA) content was significantly decreased. Similarly, RNA sequencing revealed that many genes involved in the auxin and ABA pathways were significantly differentially expressed in the CPPU treatment groups; among them, indole-3-pyruvate monooxygenase (YUCCA) was significantly upregulated and 9-cis-epoxycarotenoid dioxygenase (NCED) was significantly downregulated. IAA and ABA may thus play important roles in CPPU-induced parthenocarpy. PbTwo-component response regulator9 (PbRR9), PbYUCCA4, and PbNCED6 were then selected to further elucidate the mechanism of CPPU-induced parthenocarpy. A yeast one-hybrid assay indicated that PbRR9 can combine with the PbYUCCA4 and PbNCED6 promoters. Dual luciferase assays revealed that PbRR9 can promote and repress the activities of the PbYUCCA4 and PbNCED6 promoters, respectively. After the transient expression of PbRR9 in fruits, PbYUCCA4 expression was significantly upregulated, and PbNCED6 expression was significantly downregulated. This study uncovered a CPPU-induced parthenocarpy mechanism that is different from that in tomato. CPPU may upregulate PbYUCCA4 and downregulate PbNCED6 by upregulating PbRR9, thereby increasing IAA content and decreasing ABA content to ultimately induce parthenocarpy in ‘Dangshansu’ pear. However, because only a single time point was used and because ‘botanical’ and ‘accessory’ fruits have different structures, this conclusion is still preliminary.
... uga dapat terjadi karena pengaruh lingkungan, yaitu kondisi cuaca berupa kabut yang terjadi secara ekstrim pada bulan Juni. Bulan juni tersebut merupakan salah satu musim sebagai penyebab partenokarpi pada buah zaitun. Pada buah pir terjadi pembekuan dimalam hari, dan pada kondisi suhu yang rendah, terutama musim gugur, terjadi pada tanaman terong (Rotino et. al., 1997). Bulan Desember merupakan suatu musim dingin dengan kondisi suhu yang rendah dapat terjadi pada buah tomat (Mohammed, 1998). Selain itu, disebabkan pula dengan adanya bantuan oleh tepung sari dan serangga pada proses penyerbukan nya (Nitscb, 1952). ...
Sari. Buah merupakan organ reproduktif yang memainkan peranan penting pada tanaman dalam proses perbanyakan tanaman dan penyebaran biji. Biji akan terbentuk akibat adanya proses polinasi dan fertilisasi. Pada beberapa jenis buah keberadaan biji tidak diinginkan, sehingga sekarang sudah banyak dikembangkan buah tanpa biji atau buah partenokarpi. Secara garis besar partenokarpi terdiri dari dua kelompok utama, yaitu partenokarpi alami dan partenokarpi buatan. Pisang, tomat, dan manggis merupakan contoh tanaman yang bersifat partenokarpi alami. Pembetukan buah partenokarpi dapat dilakukan melalui beberapa cara diantaranya adalah penggunaan hormone auksin/giberelin, iridiasi polen, perubahan jumlah kromosom, gene silencing, modifikasi gen, dan genome editing tools. Review ini menjelaskan mengenai pembentukan buah partenokarpi melalui pendekatan bioteknologi.Kata Kunci: Bioteknologi, partenokarpi alami, partenokarpi buatan, buah AbstractFruit is a reproductive organ that plays an important role in plants for plant propagation and seed dispersal. Seeds will be formed due to the process of pollination and fertilization. In some types of fruit, seed in the fruit is not expected, therfore recently many study have been conducted to develop seedless fruit (parthenocarpic fruit). Seedless fruit consists of two main groups namely natural and artificial partenocarpic. Bananas, tomatoes, and mangosteen are examples of natural parthenocarpy plants. Artificial parthenokarpi fruit can be developed in several methods including the use of plant hormone i.e. auksin or gibberellin, pollen iridiation, changes in chromosome number, gene silencing, gene modification, and genome editing tools. In this review, it is explained about the formation of parthenocarp fruit through a biotechnology approach. Keywords: Biotechnology, natural parthenocarpy, artificial parthenocarpy, and fruit
... External hormonal applications like auxin or gibberellin before anthesis leads to abnormal floral organ development resulting in premature fruit drop (Gomez et al., 2008;Yao et al., 2001;Ampomah-Dwamena et al., 2002a, 2002bDaminato et al., 2014;Medina et al., 2013). Further artificial parthenocarpy, either facultative or obligate, leads to the production of small sized and/or malformed fruits with poor firmness due to the lack of uniformity or stability in the expression of parthenocarpic traits (Varoquaux et al., 2000;Gorguet et al., 2005;Rotino et al., 1997;Serrani et al., 2008). Thus to introduce heritable parthenocarpy in any horticulture crops, it is most important to identify the major molecular targets, understanding their mechanism and their role in hormonal crosstalk to avoid negative impacts in crop improvement through molecular breeding and transgenic approaches (Liu et al., 2018a(Liu et al., , 2018b. ...
Parthenocarpy is one of the most preferred plant traits, among the farmers and consumers as it enhances the quality and shelf-life of the fruits. Hormones like auxin, gibberellin (GA) and cytokinin either individually or in combination are known to induce parthenocarpy. Limitations in artificial parthenocarpy necessitates the need for understanding the underlying mechanism which is elusive. Exploring key genes in parthenocarpy are essential prerequisites to develop parthenocarpic fruit in any seeded crops through genetic manipulation. Many functional and regulatory genes have been identified from the available transcriptome data and transgenic studies of both seeded and parthenocarpic fruit development. Compared to functional genes, regulatory genes i.e. Transcription factors (TFs) could be the potential candidate genes, since fine tuning the expression of single TFs may possibly overcome the limitations in artificial parthenocarpy. But understanding the mechanism and expression of TFs under the influence of various hormones is still unclear. Hence this review is aimed to unravel the knowledge of key transcription factors involved in the complex regulatory network of parthenocarpy. Simplified model on TFs and their hormone-mediated regulation in parthenocarpic fruit set has been proposed in this review. This may lead to the identification of target TFs to be used in engineering seedless traits to enhance the fruit quality and yield in crop plants.
... The parthenocarpy character is often polygenic and therefore more difficult to deal with traditional techniques, therefore genetic mutation and alteration of ploidy level have been recently observed in olive . Transgenic parthenocarpic fruits of tobacco, eggplant and tomato were obtained successfully by Rotino et al. (1997 and1999). These plants contain the coding region of the IAAM gene (gene for tryptophan monooxygenase) in their genome, the enzyme that converts tryptophan to indolacetamide, a precursor of IAA, under the control of the sequence of a gene regulator defh9 placental-specific. ...
This review describes the regeneration and genetic transformation strategies for the main fruit trees aimed to produce cis- or
trans-genic editing tools; the risks and benefits derived from the proper use of these technologies are likewise discussed. plants
and aimed to describe the most important goals achieved up to now, included those got with genome
The plants designed and realized with genetic transformation technology for a sustainable and more profitable agriculture, are
also projected to produce specific proteins for pharmaceutical field and suitable for the climate changing to, and they are
fundamental to better understand the gene function. For this reason, this technology will still be useful or essential and, with
appropriate corrections, despite the progress the new recent technologies will survive for a long time. This technique also
allows us greatly accelerate the development of improved plants by access to the readily available and huge national local
germplasm, already gathered and preserved, avoiding the loss of important gene pool. Gene transformation technologies are
carried out over two decades and in the majority of the cases, are used to improve specifically the plants’ weak traits, providing
an answer to farmers’ demands, while leaving untouched all others traits of the most value varieties.
At moment all these improved plants are subjected to the same restrictive laws, but many optimistic people hope in some
deregulation for plants obtained by using the new tools of genome editing, beside trans-grafting and cis-genic techniques.
Meanwhile techniques to produce improved non-transgenic plants from genetically engineered mother plants are explored as
well as the techniques used to avoid the transmission of the transgenes to other compatible plants nearby.
The consequences of the total veto imposed by mostly EU governments to cultivate these plants, and in one case, as in Italy,
even the field trials, making the farmers and minor breeder companies dependent on few big companies and unable to defend
national local germplasm with an obvious negative impact on economy and on science progresses.
... Auksiinilla on keskeinen vaikutus hedelmien kehittymiseen ja säätelemällä hedelmänaiheiden auksiinisynteesiä geenitekniikan avulla on jo saatu kehitettyä partenokarppisia kasveja esimerkiksi munakoisosta (Rotino et al. 1997) ja vadelmasta (Mezzetti et al. 2001. Käytetyt auksiinit eivät indusoineet partenokarppisten marjojen kehittymistä lakkalla, vaikka joissakin tapauksissa auksiini-käsittely aiheutti marjanaiheiden osittaista kehittymistä. ...
Eggplant is one of the most consumed vegetable fruit crops in the family Solanaceae, which includes other economically important crops such as potato, tomato, pepper, chili, and tobacco. It exists in three common cultivated forms, S. melongena (brinjal eggplant), S. aethiopicum (scarlet eggplant), and S. macrocarpon (gboma eggplant), which are native to Europe, Asian, and African countries. Differences between cultivars are primarily characterized by the peel color, shape, size, and weight of the fruit, but chemical composition, fruit onset, and environmental challenges also contribute significantly to the evolution of variability and different morphological forms. Identification of useful landraces and breeding of eggplant varieties with improved yield and resistance to pests and pathogens bids a big challenge to breeders due to high level of complexity between the related species. Besides these, the close relatedness of several wild species with the cultivated type is a debatable subject because of complex species-level distinction at the molecular level, which complicates the differentiation of the taxa. A variety of biotechnological approaches and tools have contributed to the genetic improvement and expansion of eggplant ideotypes. This chapter summarizes various efforts for genetic improvement of eggplant, focusing on introducing genes into cultivated eggplant from wild species using the biotechnological approach. The present breeding status and future objectives, significance of molecular marker-assisted breeding, an overview of the QTL mapping and transcriptomic studies, development of sequencing platforms, and popular genomics tools to improve the efficiency of breeding and assist genetic improvement of eggplant shall also be discussed.
Auxin plays an essential role in plant growth and development, particularly in fruit development. The YUCCA (YUC) genes encode flavin monooxygenases that catalyze a rate-limiting step in auxin biosynthesis. Mutations that disrupt YUC gene function provide useful tools for dissecting general and specific functions of auxin during plant development. In woodland strawberry (Fragaria vesca), two EMS mutants, Y422 and Y1011, have been identified that exhibit severe defects in leaves and flowers. In particular, the width of the leaf blade is greatly reduced and each leaflet in the mutants has fewer and deeper serrations. In addition, the number and shape of the floral organs are altered, resulting in smaller fruits. Mapping by sequencing revealed that both mutations reside in the FveYUC4 gene and were therefore renamed as yuc4-1 and yuc4-2. Consistent with a role for FveYUC4 in auxin synthesis, free auxin and its metabolites are significantly reduced in the yuc4 leaves and flowers. This role of FveYUC4 in leaf and flower development is supported by its high and specific expression in young leaves and flower buds using GUS reporters. Furthermore, germline transformation of pYUC4::YUC4, which resulted in elevated expression of FveYUC4 in yuc4 mutants, not only rescued the leaf and flower defects but also produced parthenocarpic fruits. Taken together, our data demonstrate that FveYUC4 is essential for leaf and flower morphogenesis in woodland strawberry by providing auxin hormone at the proper time and in the right tissues.
Spraying N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), an exogenous cytokinin (CK) growth regulator, is the conventional method for inducing fruit set during melon (Cucumis melo L.) production; however, the mechanism by which CPPU induces fruit set is unclear. Through histological and morphological observations, the fruit size was comparable between CPPU-induced fruits and normal pollinated fruits because CPPU-induced fruits had higher cell density but smaller cell size compared to normal pollinated fruits. CPPU promotes the accumulation of gibberellin (GA) and auxin and decreases the level of abscisic acid (ABA) during fruit set. Moreover, application of the GA inhibitor paclobutrazol (PAC) partially inhibits CPPU-induced fruit set. Transcriptome analysis revealed that CPPU-induced fruit set specifically induced the GA-related pathway, in which the key synthase encoding gibberellin 20-oxidase 1 (CmGA20ox1) was specifically up-regulated. Further study indicated that the two-component response regulator 2 (CmRR2) of the cytokinin signaling pathway, which is highly expressed at fruit setting, positively regulates the expression of CmGA20ox1. Collectively, our study determined that CPPU-induced melon fruit set is dependent on GA biosynthesis, providing a theoretical basis for the creation of parthenocarpic melon germplasm.
Cucumber (Cucumis sativus L.), a major horticultural crop, in the family Cucurbitaceae is grown and consumed globally. Parthenocarpy is an ideal trait for many fruit and vegetables which produces seedless fruit desired by consumers. The seedlessness occurs when fruit develops without fertilization which can be either natural or induced. So far, a limited number of genes regulating parthenocarpic fruit set have been reported in several fruit or vegetable crops, most of which are involved in hormone biosynthesis or signalling. Although parthenocarpic cucumber has been widely used in commercial production for a long time; its genetic basis is not well understood. In this study, we retrieved thirty five parthenocarpy fruit-set related genes (PRGs) from bibliomic data in various plants. Thirty-five PRG homologs were identified in the cucumber genome via homology-based search. An in silico analysis was performed on phylogenetic tree, exon–intron structure, cis-regulatory elements in the promoter region, and conserved domains of their deduced proteins, which provided insights into the genetic make-up of parthenocarpy-related genes in cucumber. Simple sequence repeat (SSR) sequences were mined in these PRGs, and 31 SSR markers were designed. SSR genotyping identified three SSRs in two polymorphic genes. Quantitative real-time PCR of selected genes was conducted in five cucumber lines with varying degrees of parthenocarpic fruit set capacities, which revealed possible association of their expression with parthenocarpy. The results revealed that homologs CsWD40 and CsPIN-4 could be considered potential genes for determination of parthenocarpy as these genes showed parental polymorphism and differential gene expression in case of parthenocarpic and non-parthenocarpic parents.
Fruit set is a complex biological process, which determines fruit development and production. Little information is available on the fruit set and regulatory mechanism in pumpkin. In an attempt to obtain the candidate genes involved in fruit set and elucidate the regulatory networks, early growth properties of pumpkin fruit were evaluated from anthesis until 4 days post anthesis (DPA) between pollination and non-pollination treatment. The results showed that non-pollinated ovary delayed its growth and suffered the aborting process from 2 DPA, while, pollinated fruit showed an exponential growth from anthesis until 4 DPA, with notable changes in fruit length and diameter. Furthermore, RNA-seq was carried out aimed at identifying differentially expressed genes (DEGs) responsible for fruit set in pumpkin after pollination. The results revealed that a total of 7536 DEGs were screened during pumpkin fruit set after pollination, including 3406 up-regulated and 4130 down-regulated. Of these DEGs, 5180, 1594 and 762 were differentially expressed in PF_2 vs UF_2, PF_2 vs UF_0 and UF_2 vs UF_0, respectively. 644 DEGs related to cell growth, cell division, cell cycle (28), photosynthesis (15), glycometabolism (71), transcription factors (405) and plant hormone signal transduction (125) were analyzed based on functional annotation, which might play a crucial role during pumpkin fruit set. In addition, quantitative real-time PCR (qRT-PCR) analysis of 9 DEGs selected randomly indicated that RNA-seq data was reliable. Taken together, our results will provide useful gene resources for genetic improvement, and lay a theoretical foundation for understanding the molecular mechanism of pumpkin fruit set.
Parthenocarpy is an important agricultural trait that determines the yield of cucumber. The role of sugars in parthenocarpic fruit formation is unknown. Therefore, we investigated these factors by using one highly parthenocarpic line DDX and one weakly parthenocarpic line ZK. To identify the possible effect of photosynthesis on parthenocarpy, leaf of ZK and DDX were covered for limiting the synthesis of carbohydrates. Leaf covering inhibited parthenocarpic fruit initiation and growth. Sugars (sucrose, fructose and glucose) contents in CPPU-induced, pollinated fruit of ZK and non-pollinated fruit of DDX were higher than those in non-pollinated fruit of ZK. The exogenous application of sugars (especially fructose and sucrose) significantly induced the parthenocarpic fruit set and growth. Transcriptomes of fruits treated with and without exogenously applied sugars showed that genes involved in auxin signaling and cytokinin signaling were more strongly expressed in the treated fruits. Auxin responsive gene IAA14, and cytokinin responsive genes encoding histidine-containing phosphotransfer protein 4 and two-component response regulator 17 were upregulated in sugar-induced parthenocarpic fruits. These results show that parthenocarpic fruit formation is regulated by the interplay among sugars and the plant hormones auxin and cytokinin.
Solanum melongena L., commonly called as brinjal/eggplant, occupies an important position in vegetable rearing across the globe and has been regarded as the poor man’s crop. The estimated production goes over 52,309,119 metric tonnes annually. Traditional plant breeding techniques have played a vital role in developing new cultivars, thereby improving the overall crop production that catered to the needs of the global requirement. However, in the long run, the requirement has risen enormously due to the rapidly growing population. Simultaneously, the reduction in the yield due to various factors including soil quality, environmental vagaries, diseases and pest attacks posed new challenges in the production-consumption landscape. Of all the factors, the threat of the notorious insect pest, Leucinodes orbonalis, commonly known as brinjal shoot and fruit borer (BSFB) which belongs to the phylum Arthropoda and to the order Lepidoptera stood as the greatest challenge to counter as it withstood several broad range insecticides. This situation demanded for BSFB-resistant varieties of brinjal, eventually leading to the development of the genetically modified Bt brinjal. The development of such an insect-resistant variety has been a landmark in brinjal production. The present chapter focuses on transgenic brinjal with improved agronomic traits, particularly insect-resistant Bt varieties, the basic biology of Bt and the major methodologies, the mechanism of action involved in the development of the Bt brinjal.
Fruit set and growth in the absence of fertilization (parthenocarpy) is a useful trait in plants grown for the value of their fruit. Auxins and gibberellins are widely used to spray flowers to chemically confer parthenocarpy. In recent years, genetic modifications of either auxin or gibberellin biology have been used to confer parthenocarpy to tomato and other crops. Present knowledge indicates that parthenocarpy can be achieved by genetic modification of either auxin synthesis (iaaM), auxin sensitivity (rolB), auxin content (Aucsia) or auxin signal transduction (IAA9 or ARF8). Genetic modification of gibberellin signal transduction (DELLA) has also been shown to confer parthenocarpy. Available data, obtained under both open field and protected cultivation, show that genetic parthenocarpy can be used to improve fruit production and/or fruit quality. The mechanisms, genetically modified to confer parthenocarpy, are active also in other plant organs. Observations consistent with the Euanthial theory that envisages the fruit as a modified leaf predict that the mechanisms underlying fruit initiation have been recruited from molecular machineries present and controlling other plant developmental processes. The flower/fruit represents the last evolutionary innovation of the green plant lineage, and yet genes (i.e. Aucsia) controlling fruit initiation are most likely older than 1 billion years being present in Prasinophytes (i.e. probable ancestors of Charophytes, which themselves are considered ancestors of all land plants).
The sections in this article are
Introduction
Flowering Time
Flower Development
Early Fruit Development
Fruit Maturation
Conclusions
Brinjal (Solanum melongena L.) has great genetic wealth in its centre of origin, which is a foundation for crop improvement. So far, conventional breeding approaches were commonly used for improvement of yield, quality and resistance to insect pests and diseases, but the advent of biotechnological tools like embryo rescue, haploid induction, genetic transformation and molecular markers hastened the programmes in brinjal. The developments can be on understanding of evolutionary relationships, wide hybridization, genomic studies, gene editing, transgenics and doubled haploidy. The wealth of wild species can be used for introgression of resistance to Fusarium oxysporum from S. aethiopicum; Verticillium dahliae from S. linnaeanum, S. aethiopicum and S. incanum; draught from S. incanum; Verticillium wilt; and salt from Solanum sodomaeum. Male-sterile lines in cultivated S. melongena have been developed using the cytoplasm of S. aethiopicum, S. anguivi, S. kurzii, S. virginianum, S. violaceum and S. grandiflorum. Genetic transformation of Cre and Barnase gene for male sterility and Cry-1Ac gene for resistance to shoot and fruit borer are the other leads of improvement in brinjal. In the future, use of CRISPR/Cas for targeted modification of valuable traits can be exploited.
Parthenocarpic fruit formation can be achieved through the inhibition of SlIAA9, a negative regulator of auxin signalling in tomato plant. During early fruit development under SlIAA9 inhibition, cell division and cell expansion were observed. Bioactive gibberellin (GA) accumulated, but indole-3-acetic acid (IAA) and trans-zeatin did not accumulate substantially. Furthermore, under SlIAA9 inhibition, auxin-responsive genes such as SlIAA2, -3, and -14 were upregulated, and SlARF7 was downregulated. These results indicate that SlIAA9 inhibition mimics an increase in auxin. The auxin biosynthesis genes SlTAR1, ToFZY, and ToFZY5 were stimulated by an increase in auxin and by auxin mimicking under SlIAA9 inhibition. However, SlTAR2 and ToFZY2 were upregulated only by pollination followed by high IAA accumulation. These results suggest that SlTAR2 and ToFZY2 play an important role in IAA synthesis in growing ovaries. GA synthesis was also activated by SlIAA9 inhibition through both the early-13-hydroxylation (for GA1 synthesis) and non-13-hydroxylation (GA4) pathways, indicating that fruit set caused by SlIAA9 inhibition was partially mediated by the GA pathway. SlIAA9 inhibition induced the expression of GA inactivation genes as well as GA biosynthesis genes except SlCPS during early parthenocarpic fruit development in tomato. This result suggests that inactivation genes play a role in fine-tuning the regulation of bioactive GA accumulation.
Fruit development normally occurs after pollination and fertilization; however, in parthenocarpic plants, the ovary grows into the fruit without pollination and/or fertilization. Parthenocarpy has been recognized as a highly attractive agronomic trait because it could stabilize fruit yield under unfavorable environmental conditions. Although natural parthenocarpic varieties are useful for breeding Solanaceae plants, their use has been limited, and little is known about their molecular and biochemical mechanisms. Here, we report a parthenocarpic eggplant mutant, pad-1 , which accumulates high levels of auxin in the ovaries. Map-based cloning showed that the wild-type (WT) Pad-1 gene encoded an aminotransferase with similarity to Arabidopsis VAS1 gene, which is involved in auxin homeostasis. Recombinant Pad-1 protein catalyzed the conversion of indole-3-pyruvic acid (IPyA) to tryptophan (Trp), which is a reverse reaction of auxin biosynthetic enzymes, tryptophan aminotransferases (TAA1/TARs). The RNA level of Pad-1 gene increased during ovary development and reached its highest level at anthesis stage in WT. This suggests that the role of Pad-1 in WT unpollinated ovary is to prevent overaccumulation of IAA resulting in precocious fruit-set. Furthermore, suppression of the orthologous genes of Pad-1 induced parthenocarpic fruit development in tomato and pepper plants. Our results demonstrated that the use of pad-1 genes would be powerful tools to improve fruit production of Solanaceae plants.
Investigation of parthenocarpy, the production of fruit without fertilization, in multiple plant species could result in development of technologies for conferring seedless fruits and increased stability of fruit formation in economically important plants. We studied parthenocarpy in the model species Nicotiana tabacum L., and observed variability for expression of the trait among diverse genetic materials. Parthenocarpy was found to be partially dominant, and a single major quantitative trait locus on linkage group 22 was found to control the trait in a doubled haploid mapping population derived from a cross between parthenocarpic cigar tobacco cultivar “Beinhart 1000” and nonparthenocarpic flue-cured tobacco cultivar, “Hicks.” The same genomic region was found to be involved with control of the trait in the important flue-cured tobacco cultivar, “K326.” We also investigated the potential for the production of maternal haploids due to parthenogenesis in parthenocarpic tobacco seed capsules. Maternal haploids were not observed in parthenocarpic capsules, suggesting a requirement of fertilization for maternal haploid production due to parthenogenesis in N. tabacum.
The success of in vitro plant regeneration and the competence of genetic transformation greatly depends on the genotype of the species of interest. In previous work, we developed a method for the efficient Agrobacterium-mediated genetic transformation via organogenesis of V. vinifera cultivar Thompson Seedless, by using meristematic bulk (MB) as starting tissue. In this study, we applied this method for the regeneration and transformation of MBs obtained from the Italian cultivar Ciliegiolo and two of the commonly used Vitis rootstocks, 110 Richter and Kober 5BB, in comparison with Thompson Seedless. The A. tumefaciens strain EHA105, harbouring pK7WG2 binary vector, was used for the transformation trials, which allowed selection through the enhanced-green fluorescent protein (eGFP) and the neomycin phosphotransferase (nptII) gene. Putative transformed tissues and/or shoots were identified by either a screening based on the eGFP expression alone or its use in combination with kanamycin in the medium. MBs obtained from Thompson Seedless showed the highest regeneration and transformation cell competence, which subsequently allowed the recovery of stably transformed plants. Ciliegiolo, 110 Richter, and Kober 5BB, produced actively growing transgenic calli showing eGFP fluorescence, more consistently on selective media, but had no regenerative competence.
Parthenocarpy was induced in emasculated strawberry ( Fragaria × ananassa Duch.) flowers with aqueous solutions of 10 ⁻³ M NAA, GA 3 or GA 4+7 in 2% DMSO plus 0.1% Tween 80. All fruit except those treated with NAA stopped growing within 12 days of treatment. Repeat application with NAA or GA 4+7 20 days after initial treatment stimulated continued growth of NAA-induced fruit, but had little or no effect on growth of GA 4+7 -induced fruit. The diameters of mature parthenocarpic fruit ranged from 70% to 90% of that of pollinated fruit. Achene removal 12 days after pollination greatly reduced subsequent growth of receptacle tissue, complete removal being more effective than partial removal. Following achene removal 16 days after pollination, treatment with aqueous solutions of NAA in 2% DMSO and 0.1% Tween 80 produced receptacles 75% the size of controls with intact achenes, but neither GA 3 nor GA 4+7 stimulated growth. Achene removal 24 days after pollination did not influence further receptacle enlargement. Concentration of free indoleacetic acid (IAA) in NAA-treated fruit was 5-times that in controls and 3-times that in GA 4+7 -treated fruit 6 days after treatment. By 14 days after treatment, the levels had declined in all treated fruit. Free IAA concentration in the receptacle tissue of intact fruit was nearly equal to or greater than that in achenes 14 days after pollination. The growth rates of receptacles were positively correlated with numbers of intact achenes and free IAA content of the receptacle. Chemical names used: naphthaleneacetic acid (NAA); gibberellins (GA 3 or GA 4+7 ); dimethylsulfoxide (DMSO)
The actions of plant regulators in set and development of fruits are well known. However, the presence and function of endogenous hormones in parthenocarpic fruits have still not been sufficiently investigated. A comparison between seeded and seedless fruits makes it possible to obtain a more accurate understanding of some relationships between growth regulators and stages of fruit development. Endogenous auxin and gibberellin activity levels and some growth parameters (fresh and dry weight, cell number and cell volume, DNA content) have been determined in tomato fruits (Lycopersicon esculentum Mill.) of the cultivar Ventura and of its isogenic parthenocarpic mutant. In both genotypes, auxin and gibberellin are present in the first week after anthesis, though at different concentrations and with different patterns. These two activities are involved in fruit setting. The simultaneous occurrence of maximum auxin concentration and of the beginning of cell enlargement, in both genotypes, shows that the activity present at this time starts fruit development and possibly determines the size of the fruits.
High auxin activity is observed only in seeded fruits 20–40 days after anthesis, and it is probably synthesized by seeds. Gibberellin activity is present, corresponding to the change in fruit development from the mature green to pink stages.
A modified gene of Bacillus thuringiensis var. Tolworthi (Bt), encoding a coleopteran insect-specific CryIIIB toxin, was transferred via Agrobacterium tumefaciens to the female parent of the eggplant commercial F1 hybrid ‘Rimina’. One-hundred and fifty eight transgenic plants were regenerated and tested by PCR and NPTII expression assays.
The presence of the CryIIIB toxin in leaf extracts was demonstrated in 57 out of 93 transgenic plants tested by DAS-ELISA
assay. High Bt-expressing plants contained a 74-kDa protein cross-reacting with serum anti-CryIIIB toxin. Twenty three out
of 44 S. melongena plants tested by insect bioassay showed significant insecticidial activity on neonate larvae of Colorado Potato Beetle (CPB).
The Bt transgene and the toxic effect on CPB larvae were transmitted to progenies derived by selfing. Thus, transgenic Bt
eggplants represent a very effective means of CPB pest control.
Nitsch, J. P., C. Pratt, C. Nitsch, and N. J. Shaulis (Cornell U., Ithaca, N. Y.) Natural growth substances in Concord and Concord Seedless grapes in relation to berry development. Amer. Jour. Bot. 47(7): 566–576. Illus. 1960.—A comparative study was made of the development of the grape berry in the ‘Concord’ variety and its presumed mutant, ‘Concord Seedless.’ This study included fresh and dry weight determinations, embryological observations, measurements of growth substances active on the oat first-internode test and preliminary determination of other growth factors stimulating the growth of excised Jerusalem artichoke tissues in aseptic cultures. Four phases could be distinguished in the growth of the ‘Concord’ berry: Period O—limited growth and low growth-substance content; Period I—rapid growth and high growth-substance concentration; Period II—marked slowing down in growth and sudden drop in the growth-substance level; and Period III—resumption of active increase in fresh and dry weight with no increase in growth-substance concentration. In the ‘Concord Seedless’ variety, growth of the nucellus and production of growth substances increased faster during Period 0 than in ‘Concord,’ but degeneration of the endosperm and reduction in the growth-substance level followed during the middle of Period I. Period II was inconspicuous. Early growth-substance production in both varieties seemed to be associated with nucellus rather than with endosperm development. Some 6 different substances promoting growth in the Avena first-internode test could be separated on paper chromatograms. None of them was chemically identified.
The expression of parthenocarpy in the tomato cultivar Severianin is facuttative, producing seeded and/or seedless fruits depending on the environmental conditions. The genetics of this facuitative parthenocarpy in Severianin was verified as being controlled by a single recessive gene, pat-2 . Expressivity of pat-2 is strong in environments unfavorable for normal pollination and fertilization of flowers in tomato; for example, high night and day temperatures in midsummer in Urbana, Illinois. Plant breeders should find this trait useful as an adjunct system to promote fruit setting in tomato, particularly in stress environments where it has the ability to form normal but seedless fruits. Selection for parthenocarpy without the labor-intensive procedure of emasculation is efficient when segregating populations are grown in temperature stress environments. This parthenocarplc gene may be associated with determinate growth habit and/or earliness through pleiotropic effects and not genetic linkages. No genetic linkages were detected with aw, c, ps, u , and y .
The flowering-pattern of the eggplant affected fruit quality during the cool season, mainly by the position of the flower in the inflorescence. “Additional” flowers, which set fruit during this season only, and the fruits of which grow more slowly than those originating in “basal” flowers, accounted for a considerable part of both undersized fruits and those with inferior color.
A “plant gene vector cassette” to be used in combination with various Escherichia coli gene-cloning vectors was constructed. This cassette contains a replication and mobilization unit which allows it to be maintained and to be transferred back and forth between E. coli and Agrobacterium tumefaciens hosts provided these hosts contain plasmid RK2 replication and mobilization helper functions. The cassette also harbors a transferable DNA unit with plant selectable marker genes and cloning sites which can be combined with different bacterial replicons, thus facilitating the reisolation of transferred DNA from transformed plants in E. coli. The vector cassette contains two different promoters derived from the T-DNA-encoded genes 5 and nopaline synthase (NOS). By comparing the levels of expression of the marker enzymes linked to each of these promoter sequences, it was found that the gene 5 promoter is active in a tissue-specific fashion whereas this is not the case for the NOS promoter. This observation provides the first documented instance of a gene derived from a procaryotic host the expression of which is apparently regulated by plant growth factors.
Alterations to the biological activities of phytohormones can result in modifications of plant physiological and developmental processes. Microbial organisms that are pathogens or symbionts of plants are natural models for studying such modifications. Several genes of bacterial origin able to alter phytohormone content and activity in plants have been characterized, including genes whose products can synthesize and modify phytohormones and/or hydrolyze phytohormone conjugates. Their expression in transgenic plants has confirmed that several morphological and physiological traits can be altered simultaneously by the expression of a single gene. This approach has been shown to be of value not only in achieving a better understanding of the fundamental mechanisms underlying growth and development in plants, but also in attaining agriculturally important goals, such as the control of ripening.
The enzymatic conversion of indole-3-acetamide (IAM) to IAA, which is the second step in the IAM pathway (tryptophan → IAM → IAA) was investigated in calluses derived from various dicotyledonous and monocotyledonous plants. A simple method, using analysis by HPLC to measure the conversion of naphthaleneacetamide (NAM) to naphthaleneacetic acid (NAA) was employed for the detection of IAM hydrolase activity. Among calluses from 27 plants tested, only callus from a cultivated strain of rice (Oryza sativa C5924) had high conversion activity similar to that of crown gall cells, and very weak activity was found in calluses from lucern and orange. In addition to the presence of the conversion activity, we confirmed that radioactivity from 3H-IAM was incorporated into IAA in a cell-free system from O. sativa C5924. An extract of roots of rice seedlings exhibited twice the activity of that in an extract of shoots. IAM hydrolase activity was observed in calluses from all lines of rice callus examined, irrespective of whether they were wild or cultivated lines, with the exception of O. grandiglumis W1194 and O. branchyantha W656, while other species of Gramineae exhibited no activity. These results suggest the possibility that this enzyme may play a specific role in rice.
Anomalous flowering of the Antirrhinum majus mutant squamosa (squa) is characterized by excessive formation of bracts and the production of relatively few and often malformed or incomplete flowers. To study the function of squamosa in the commitment of an inflorescence lateral meristem to floral development, the gene was cloned and its genomic structure, a well as that of four mutant alleles, was determined. SQUA is a member of a family of transcription factors which contain the MADS-box, a conserved DNA binding domain. In addition, we analysed the temporal and spatial expression pattern of the squa gene. Low transcriptional activity of squa is detectable in bracts and in the leaves immediately below the inflorescence. High squa transcript levels are seen in the inflorescence lateral meristems as soon as they are formed in the axils of bracts. Squa transcriptional activity persists through later stages of floral morphogenesis, with the exception of stamen differentiation. Although necessary for shaping a normal racemose inflorescence, the squa function is not absolutely essential for flower development. We discuss the function of the gene during flowering, its likely functional redundancy and its possible interaction with other genes participating in the genetic control of flower formation in Antirrhinum.
We report the nucleotide sequences of iaaM and iaaH, the genetic determinants for, respectively, tryptophan 2-monooxygenase and indoleacetamide hydrolase, the enzymes that catalyze the conversion of L-tryptophan to indoleacetic acid in the tumor-forming bacterium Pseudomonas syringae pv. savastanoi. The sequence analysis indicates that the iaaM locus contains an open reading frame encoding 557 amino acids that would comprise a protein with a molecular weight of 61,783; the iaaH locus contains an open reading frame of 455 amino acids that would comprise a protein with a molecular weight of 48,515. Significant amino acid sequence homology was found between the predicted sequence of the tryptophan monooxygenase of P. savastanoi and the deduced product of the T-DNA tms-1 gene of the octopine-type plasmid pTiA6NC from Agrobacterium tumefaciens. Strong homology was found in the 25 amino acid sequence in the putative FAD-binding region of tryptophan monooxygenase. Homology was also found in the amino acid sequences representing the central regions of the putative products of iaaH and tms-2 T-DNA. The results suggest a strong similarity in the pathways for indoleacetic acid synthesis encoded by genes in P. savastanoi and in A. tumefaciens T-DNA.
Plant growth substance-including application in agriculture
- H N Khishnamoorthy
- HN Khishnamoorthy