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Actinidia eriantha: A parental species for breeding kiwifruit with novel peelability and health attributes
Abstract
Consumers will pay a premium for fruit that have excellent flavour, high nutritional value, store well and are convenient to eat. In kiwifruit, the opportunity to breed fruit with these characteristics exists within the ~50 species that make up the Actinidia genus. Actinidia eriantha has been identified as having desirable convenience and health attributes that could be introgressed into commercial kiwifruit species by conventional breeding. Actinidia eriantha has an 'easy-to-peel' phenotype that increases the level of convenience associated with kiwifruit by making fruit easier to eat. In this review we describe analysis of biochemical and chemical differences in cell walls of easy-to-peel versus poor-peeling genotypes, and how these relate to their mechanical, structural and chemical features. We also discuss the health attributes of A. eriantha, including its content of vitamin C, oxalate, triterpenoids and allergens. © 2009 New Zealand Forest Research Institute Limited, trading as Scion.
... However, compared with bananas, mandarin, and other easy-to-peel fruits, the main selling varieties in the current kiwifruit commercial market, such as Actinidia deliciosa and A. chinensis, are generally difficult to peel. The fruit of A. eriantha is easier to peel after soft ripening compared to other kiwifruit varieties and is considered to be an excellent parental species for cultivating new varieties with novel peelability and high nutritional value (Atkinson et al., 2009). Microscopy observations showed that the peeling of A. eriantha does not have specific tissues that are conductive to form obvious abscission-like zones compared to citrus and banana peels (Harker et al., 2011). ...
... Microscopy observations showed that the peeling of A. eriantha does not have specific tissues that are conductive to form obvious abscission-like zones compared to citrus and banana peels (Harker et al., 2011). Relatively small structural differences were observed in the peel region during the development of detachment between good-peeling and poor-peeling genotypes of A. eriantha (Atkinson et al., 2009;Prakash et al., 2017). The distribution and types of pectin in peel and outer pericarp tissues were different between good-peeling and poor-peeling genotypes of A. eriantha, which might be the main reason for the formation of different peeling behaviors (Atkinson et al., 2009). ...
... Relatively small structural differences were observed in the peel region during the development of detachment between good-peeling and poor-peeling genotypes of A. eriantha (Atkinson et al., 2009;Prakash et al., 2017). The distribution and types of pectin in peel and outer pericarp tissues were different between good-peeling and poor-peeling genotypes of A. eriantha, which might be the main reason for the formation of different peeling behaviors (Atkinson et al., 2009). The differences in the degree of pectin methylesterification, galactose loss, and the activities of polygalacturonase and xyloglucan transglycosylase/hydrolases in peel and outer pericarp tissues were the main aspects that led to the formation of contrasting peelability in A. eriantha (Prakash et al., 2017). ...
Actinidia eriantha is prone to peeling at the soft ripening stage, which is a unique characteristic that distinguishes it from other Actinidia species. However, the mechanism underlying the formation of peelability in A. eriantha is still not very clear. In this study, two A. eriantha varieties with contrasting peeling behavior were used as materials and the peel cell wall metabolism-related substances and enzyme activities were detected during fruit development. The peel cell structures were observed and the transcriptome and metabolome analysis were performed. The results indicated that the firmness and toughness of the fruit peel affect the peelability of A. eriantha. The increased activities of β-galactosidase, pectinase, and cellulase promoted the degradation of lignin, cellulose, hemicellulose, and total pectin, and ultimately affected the peelability. The anatomical structure showed that the staining intensity on the peel of the two varieties did not change much at different stages. The differential metabolites were mainly flavonoids, lipids, and phenolic acids. Eight genes that may be related to fruit peeling traits of A. eriantha were identified, three of which (AeGAE6, AebHLH35-like, and AeBGAL5) may be the main genes affecting the peelability of A. eriantha. These candidate genes may affect the peelability of A. eriantha by influencing the metabolism of cell wall components such as galactose, mannose, arabinose, and glucuronic acid.
... Actinidia eriantha Benth. is a kiwifruit species which produces fruit with a bland and unpalatable flavour. It is covered in fine, white hairs, but can be easily peeled, and thus, has the genetic potential to generate new kiwifruit cultivars with convenient attributes (Atkinson, Sharma, Hallet, Johnston, & Schröder, 2009). One cultivar of A. eriantha, 'Bidan', has been released in Korea (Jo, Cho, Park, & Bang, 2007) and another one, 'White', in China (Wu et al., 2009). ...
... The generation of new kiwifruit cultivars that can be peeled by hand would thus combine the positive attributes of flavour, health and convenience. Among Actinidia species, A. eriantha is the only one producing easy to peel fruit when ripe (Atkinson et al., 2009), although Actinidia arguta fruit have edible skins. ...
... A. eriantha has a high vitamin C content, which is significantly higher than that of commercial species, and can reach concentrations up to 8 mg/g (Atkinson et al., 2009). As in several Actinidia species, the roots of A. eriantha have also been reported to contain triterpenes, such as ursolic acid, a compound with anti-inflammatory, anti-tumour, and anti-microbial activities (Huang, Zhang, Li, & Zhou, 1988;Liu, 2005). ...
Aroma compounds in fruit are known to occur in free and glycosidically bound forms. The bound volatile fraction of a low flavour kiwifruit species, Actinidia eriantha, was studied. The fruit have a bland and grassy flavour. Glycosidic precursors were isolated from juice by adsorption onto an Amberlite XAD-2 column. After enzymatic hydrolysis with Rapidase AR2000, the released aglycones were analysed by GC-MS. Alcohols, terpenoids and phenolics were the most numerously represented compound classes. Alcohols, benzenoids and phenolics showed the highest concentrations. Major compounds were 2-phenylethanol, furfuryl alcohol, (Z)-3-hexen-1-ol, coniferyl alcohol, isoamyl alcohol and linolenic acid. Several of the bound compounds found, including linoleic, linolenic and benzoic acids and coniferyl alcohol, are precursors of odorous volatiles. Many compounds detected as bound volatiles have not been previously reported as free volatiles in A. eriantha. The bound volatile composition of A. eriantha also showed differences with those of other kiwifruit species.
... A. deliciosa fruit (including the predominant 'Hayward' cultivar) are typically large (∼100 g) and green-fleshed; A. chinensis fruit are also large and can be green-, yellow-('Hort16A'), or red-fleshed ('Hongyang'); A. arguta fruit are small (<25 g), hairless, and sweet, 35 while A. eriantha fruit are small, hairy, high in vitamin C, and potentially easy to peel. 36 In this paper we characterize the diversity and relative levels of actinidin, kiwellin, and TLP proteins in 15 different varieties of kiwifruit selected from these four commonly cultivated kiwifruit species. ...
... Detailed fruit descriptions for each variety can be found for 'Hayward', 'Bruno', 'Hort16A', and 'Jin Feng' in Ferguson and Huang, 37 for 'Qinmei', 'Lushan-xiang' and 'Hongyang' in Xiao, 38 and for A. arguta 'Hortgem Tahi', 'Hortgem Rua', 'Hortgem Toru', and 'Hortgem Wha' in Williams et al. 35 The A. eriantha varieties GPA, GPB, PPA, and PPB are breeding selections that have been used in development of peelable kiwifruit varieties. 36 PPA and PPB are full siblings; 'HortGem Tahi' and 'HortGem Wha' are half siblings; otherwise, the varieties are not closely related genetically. ...
In the last 30 years the incidence of kiwifruit allergy has increased with the three major allergenic proteins being identified as actinidin, kiwellin and thaumatin-like protein (TLP). We report wide variation in the levels of actinidin and TLP in 15 kiwifruit varieties from the four most widely cultivated Actinidia species. Acidic and basic isoforms of actinidin were identified in A. deliciosa 'Hayward' and A. arguta 'Hortgem Tahi', whilst only a basic isoform of actinidin was identified in A. chinensis 'Hort16A'. One isoform each of kiwellin and TLP were identified in ripe fruit. The cysteine protease activity of actinidin correlated with protein levels in all species except A. arguta. Protein modeling suggested that modifications to the S2 binding pocket influenced substrate specificity of the A. arguta enzyme. Our results indicate that care is necessary when extrapolating allergenicity results from single varieties to others within the same and between different Actinidia species.
... Owing to its strong resistance to Pseudomonas syringae pathovar Actinidiae, long shelf-life, enriched ascorbic acid, and peelable skin [7][8][9][10][11], A. eriantha (2n = 58) has been favored in kiwifruit breeding. Recently, new cultivars have been selected either from the wild germplasm of A. eriantha such as "White" (Fig. 1) or from the interspecific hybridization between A. eriantha (male) and A. chinensis (female) such as "Jinyan" [7,12]. ...
This protocol includes a computational pipeline used in assembly and annotation of Kiwifruit Actinidia eriantha genome.
... The inflorescence and fruit surface of A. eriantha are densely covered with white or grayish-white short hairs, and is the most important morphological feature of A. eriantha that distinguishes it from other Actinidia species [2]. The fruit of A. eriantha is usually long and cylindrical, with dark green flesh that is easy to peel when the fruit is ripe [3]. Among the plants of the genus Actinidia, the size of A. eriantha fruit is only smaller than that of the main varieties of A. chinensis and A. deliciosa. ...
In order to better understand the changes in fruit quality and soluble sugar components in wild Actinidia eriantha at the soft ripening stage, this study explored the fruit quality indexes, soluble sugar components, sucrose metabolism-related enzyme activities and the expression of sucrose metabolism-related enzyme genes in wild A. eriantha germplasm resources. The results showed that the fruit quality of wild A. eriantha at the soft ripening stage was quite different, and the coefficient of variation of fructose content was the largest, followed by sucrose and glucose. Principal component analysis and systematic clustering analysis showed that the comprehensive performance of fruit quality indexes of M28 and M10 was the most prominent. The accumulation and composition of soluble sugar components in different wild A. eriantha varieties (lines) were not consistent. The activities of sucrose metabolism enzymes among wild A. eriantha varieties (lines) were different to some extent. The sucrose metabolism-related enzyme genes among wild A. eriantha germplasm resources had different expression patterns. The results will contribute to understanding the fruit quality changes and the mechanism of sugar metabolism in wild A. eriantha at the soft ripening stage, and lay a foundation for the protection and utilization of wild A. eriantha germplasm resources.
... The content of AsA in the fruit of A. eriantha is 3 or 4 times higher than that of A. chinensis (Zhong et al. 2011). It also contains lots of organic compounds, such as polyphenols, flavonoids, cellulose, and amino acids, as well as other minerals needed by the human body , G. Liao et al. and its pericarp is easy to peel off (Atkinson et al. 2009;Huang et al. 2015). A. eriantha has strong heat and canker tolerance (Zhang 2017;Wang et al. 1996). ...
Flowers of novel female kiwifruit cultivar ‘Ganmi 6’ (diploid Actinidia eriantha) were hand pollinated with pollen from each of five males: ‘XM 11’ (diploid A. chinensis), ‘YS 1’ (diploid A. chinensis), ‘WF 1’ (diploid A. eriantha), ‘MG 15’ (diploid A. eriantha) and ‘FX 2’ (CK, hexaploid A. deliciosa, widely used as pollinating male of A. eriantha). The resulting fruits were harvested when SSC reached 6.5% and quality was measured when it reached an edible state at room temperature. When harvested, fruit from pollination by ‘WF1’ had a 100% fruit setting rate. The fruit weights were significantly higher following ‘MG 15’ and ‘WF 1’ pollination. No significant differences were found among pollen treatments in fruit shape index and small width. However, there were significant differences in fruit weight, soluble sugar content, titratable acid content, dry matter and ascorbic acid content. Comprehensive evaluation of male pollination plants was determined by membership function method with the fruit setting rate and fruit quality, the results were as follows: ‘WF 1’ > ‘XM 11’ > ‘MG 15’ > ‘FX 2’ > ‘YS 1’. ‘WF 1’ is the most suitable for pollinating ‘Ganmi 6’ in industry.
... Owing to its strong resistance to Pseudomonas syringae pv. Actinidiae, long shelf-life, enriched ascorbic acid and peelable skin [7][8][9][10][11], A. eriantha (2n=58) has been favored in kiwifruit breeding. Recently, new cultivars have been selected either from the wild germplasm of A. eriantha such as 'White' (Fig. 1) or from the interspecific hybridization between A. eriantha (♂) and A. chinensis (♀) such as 'Jinyan' [7,12]. ...
... Owing to its strong resistance to Pseudomonas syringae pathovar Actinidiae, long shelf-life, enriched ascorbic acid, and peelable skin [7][8][9][10][11], A. eriantha (2n = 58) has been favored in kiwifruit breeding. Recently, new cultivars have been selected either from the wild germplasm of A. eriantha such as "White" (Fig. 1) or from the interspecific hybridization between A. eriantha (male) and A. chinensis (female) such as "Jinyan" [7,12]. ...
Background
Kiwifruit (Actinidia spp.) is a dioecious plant with fruits containing abundant vitamin C and minerals. A handful of kiwifruit species have been domesticated, among which Actinidiaeriantha is increasingly favored in breeding owing to its superior commercial traits. Recently, elite cultivars from A. eriantha have been successfully selected and further studies on their biology and breeding potential require genomic information, which is currently unavailable.
Findings
We assembled a chromosome-scale genome sequence of A. eriantha cultivar White using single-molecular sequencing and chromatin interaction map–based scaffolding. The assembly has a total size of 690.6 megabases and an N50 of 21.7 megabases. Approximately 99% of the assembly were in 29 pseudomolecules corresponding to the 29 kiwifruit chromosomes. Forty-three percent of the A. eriantha genome are repetitive sequences, and the non-repetitive part encodes 42,988 protein-coding genes, of which 39,075 have homologues from other plant species or protein domains. The divergence time between A. eriantha and its close relative Actinidia chinensis is estimated to be 3.3 million years, and after diversification, 1,727 and 1,506 gene families are expanded and contracted in A. eriantha, respectively.
Conclusions
We provide a high-quality reference genome for kiwifruit A. eriantha. This chromosome-scale genome assembly is substantially better than 2 published kiwifruit assemblies from A. chinensis in terms of genome contiguity and completeness. The availability of the A. eriantha genome provides a valuable resource for facilitating kiwifruit breeding and studies of kiwifruit biology.
... It was suggested that regular kiwifruit consumption may provide supplementary protection against to cardiovascular disease and cancer thanks to its impact on oxidative stress [4]. In the genus, Actinidia eriantha is the third biggest variety with desirable features that can be transferred into commercial kiwifruit species by artificial breeding [5]. Lots of wild A. eriantha fruits are small, usually weigh from 20 to 40 g, and too acidic for commercialization. ...
Our study was conducted to determine In vitro germination ability of pollens from 25 wild Actinidia eriantha genotypes after one year freeze storage, after-wards we examined fertilization ability of stored pollens of 8 genotypes selected according to In vitro test results from aforementioned 25 genotypes, and finally investigated effects of stored viable pollens from " MH67 " , " MH55 " , " MH48 " and " MH45 " genotypes on fruit quality characters of the female experimental plant " M3 " as the main purpose. Non-pollinated " M3 " kiwifruit plant was taken as control. We found that In vitro germination and fertilization ability of different stored pollen sources, and also fruit quality characters including dry matter, total sugar, titratable acid, vitamin C, total polyphenol, total flavonoid, chlorophyll (" a " , " b " , and total) and carotenoid contents except total soluble solid content were significantly different. MH67 and MH45 genotypes were evaluated as the most suitable pollenizers which can be recommended as new candidate cultivars because of long term storage ability and brought about desired fruit quality characters. They also will be investigated more at further breeding studies.
... The fruit of one kiwifruit (Actinidia) species, A. eriantha, typically become peelable when they are ripe and soft [28]. However, there are wide variations in location of peel detachment in the outer pericarp cell layers, and how cleanly the cells debond in this detachment zone. ...
Background
Unlike in abscission or dehiscence, fruit of kiwifruit Actinidia eriantha develop the ability for peel detachment when they are ripe and soft in the absence of a morphologically identifiable abscission zone. Two closely-related genotypes with contrasting detachment behaviour have been identified. The ‘good-peeling’ genotype has detachment with clean debonding of cells, and a peel tissue that does not tear. The ‘poor-peeling’ genotype has poor detachability, with cells that rupture upon debonding, and peel tissue that fragments easily.
Results
Structural studies indicated that peel detachability in both genotypes occurred in the outer pericarp beneath the hypodermis. Immunolabelling showed differences in methylesterification of pectin, where the interface of labelling coincided with the location of detachment in the good-peeling genotype, whereas in the poor-peeling genotype, no such interface existed. This zone of difference in methylesterification was enhanced by differential cell wall changes between the peel and outer pericarp tissue. Although both genotypes expressed two polygalacturonase genes, no enzyme activity was detected in the good-peeling genotype, suggesting limited pectin breakdown, keeping cell walls strong without tearing or fragmentation of the peel and flesh upon detachment. Differences in location and amounts of wall-stiffening galactan in the peel of the good-peeling genotype possibly contributed to this phenotype. Hemicellulose-acting transglycosylases were more active in the good-peeling genotype, suggesting an influence on peel flexibility by remodelling their substrates during development of detachability. High xyloglucanase activity in the peel of the good-peeling genotype may contribute by having a strengthening effect on the cellulose-xyloglucan network.
Conclusions
In fruit of A. eriantha, peel detachability is due to the establishment of a zone of discontinuity created by differential cell wall changes in peel and outer pericarp tissues that lead to changes in mechanical properties of the peel. During ripening, the peel becomes flexible and the cells continue to adhere strongly to each other, preventing breakage, whereas the underlying outer pericarp loses cell wall strength as softening proceeds. Together these results reveal a novel and interesting mechanism for enabling cell separation.
Electronic supplementary material
The online version of this article (doi:10.1186/s12870-017-1034-2) contains supplementary material, which is available to authorized users.
... The fruit of A. eriantha contains exceptionally high levels of vitamin C (more than 800 mg/100 g fresh weight) (Wu et al. 2009). As a result, A. eriantha may be used as parental material to develop new kiwifruit cultivars with beneficial traits (Atkinson et al. 2009). ...
Kiwifruit has a high commercial value and is especially rich in vitamin C. Successful fruit set in kiwifruit depends on several reproductive processes including pollen germination and pollen tube growth. In this study, we investigated impacts of heat stress temperatures (27, 30, 33 and 36 °C) on pollen germination and pollen tube growth of 25 wild genotypes of Actinidia eriantha. Before heat stress application, pollens were stored at −20 °C for 6 months. The results showed great variation among genotypes in each treatment. Eight genotypes showed no significant change in the reduction of germination percentage. Some genotypes gave unsteady response in tube growth. MH22, MH30 and MH58 were evaluated as more tolerant genotypes. In contrast, MH48 and MH67 were the two most sensitive genotypes. The research of heat stress impact on pollen germination and pollen tube growth will be helpful for breeding new varieties and the identified tolerant genotypes can be used in future breeding programmes.
... Actinidia eriantha Benth. is a species that can be used to generate new, peelable cultivars, and is also known for its high vitamin C content, with concentrations as high as 8 mg/g having been reported. The fruit have also been described as bland and not very tasty (Atkinson, Sharma, Hallet, Johnston, & Schr€ oder, 2009). The volatile content of A. eriantha is lower than in other Actinidia cultivars. ...
... Actinidia eriantha Benth. is a species that can be used to generate new, peelable cultivars, and is also known for its high vitamin C content, with concentrations as high as 8 mg/g having been reported. The fruit have also been described as bland and not very tasty (Atkinson, Sharma, Hallet, Johnston, & Schr€ oder, 2009). The volatile content of A. eriantha is lower than in other Actinidia cultivars. ...
The commercially available kiwifruit species are appreciated for their flavour and distinctive appearance. The aromas of the commercial species Actinidia deliciosa ‘Hayward’, Actinidia chinensis ‘Hort16A’ and Actinidia arguta have been studied applying diverse analytical techniques. Major volatile compounds and important odorants have been identified. The effects of ripening and storage have been evaluated. The perception of kiwifruit flavour by consumers has been assessed, also considering the need to identify flavour targets for breeding. The present review in addition gives insights on the new research area concerning gene regulation of the aroma of kiwifruit.
... In Cluster 1, two major allergens, d1 and an isomer d1.029, were identified as up-regulated proteins (spot 5014 and 7126), as well as the thaumatin-like protein (spot 9332). It was reported that gene expression of a protein sharing 90% sequence homology with Mal d1 was up-regulated in response to ethylene [49]. Those results are also in agreement with the report that Mal d1 apple allergens are enhanced by fruit ripening and under the regulation of ethylene [50]. ...
Plant disease outbreaks are increasing in a world facing climate change and globalized markets, representing a serious threat to food security. Kiwifruit Bacterial Canker (KBC), caused by the bacterium Pseudomonas syringae pv. actinidiae (Psa), was selected as a case study for being an example of a pandemic disease that severely impacted crop production, leading to huge economic losses, and for the effort that has been made to control this disease. This review provides an in-depth and critical analysis on the scientific progress made for developing alternative tools for sustainable KBC management. Their status in terms of technological maturity is discussed and a set of opportunities and threats are also presented. The gradual replacement of susceptible kiwifruit cultivars, with more tolerant ones, significantly reduced KBC incidence and was a major milestone for Psa containment – which highlights the importance of plant breeding. Nonetheless, this is a very laborious process. Moreover, the potential threat of Psa evolving to more virulent biovars, or resistant lineages to existing control methods, strengthens the need of keep on exploring effective and more environmentally friendly tools for KBC management. Currently, plant elicitors and beneficial fungi and bacteria are already being used in the field with some degree of success. Precision agriculture technologies, for improving early disease detection and preventing pathogen dispersal, are also being developed and optimized. These include hyperspectral technologies and forecast models for Psa risk assessment, with the latter being slightly more advanced in terms of technological maturity. Additionally, plant protection products based on innovative formulations with molecules with antibacterial activity against Psa (e.g., essential oils, phages and antimicrobial peptides) have been validated primarily in laboratory trials and with few compounds already reaching field application. The lessons learned with this pandemic disease, and the acquired scientific and technological knowledge, can be of importance for sustainably managing other plant diseases and handling future pandemic outbreaks.
To evaluate the domestication and cultivation value of wild Actinidia eriantha germplasm resources in the mountainous areas of southern China, 145 genotypes collected in the Magu Mountain Nature Reserve, Jiangxi Province, were assessed for fruit quality. The results showed there was significant variation between genotypes in the sugar, dry matter, titratable acidity, soluble solids, carotenoid, chlorophyll and ascorbic acid contents of their fruit. Ascorbic acid content was positively correlated with titratable acidity, and there were pairwise positive correlations among the total sugar, dry matter and soluble solids contents. Cluster analysis showed that the resources of wild A. eriantha could be divided into six groups at a genetic distance of 1.486.
Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is a catastrophic disease which threatens the global kiwifruit industry. As yet, no cure has been developed. Planting resistant cultivars is considered as one of the most effective ways to control Psa. However, most existing cultivars lack Psa‐resistance genes. Wild Actinidia resources contain rich genetic diversity and may have powerful disease‐resistance genes under long‐term natural selection, but the lack of the knowledge of resistance to Psa for most Actinidia species results in some excellent wild resistant genotypes being underutilized. In this study, the response to Psa of 104 wild genotypes of 30 Actinidia species (including 37 taxa) was tested with an in vitro bioassay, and a considerable number of individuals from different species with tolerance or high resistance to Psa were identified. The results showed high consistency between years (P < 0.01). This is the first large‐scale evaluation of diverse Actinidia species in resistance to Psa through an in vitro bioassay. The resistant genotypes of A. chinensis identified could be used in future kiwifruit improvement programmes. The findings should help provide an understanding of the resistance to Psa.
In order to establish the link between fruit quality traits and genotypes with specific allelic variations, one hundred and forty five wild kiwifruit (A. eriantha) germplasm resources were used to evaluate the fruit quality, and their SSR markers were used to analyze the genetic diversity and also the correlation between the natural variation of their main inner qualities and SSR markers in this study. The results showed that there were abundant variations in the main inner quality of the tested materials, among which the variation coefficient of soluble sugar content (SS) was the largest, followed by carotenoid content (Car) and chlorophyll content (Chl). Sixteen excellent wild A. eriantha germplasms were selected by principal component analysis. Genetic diversity analysis of SSR markers showed that the number of alleles detected per pair of primers was 3˜13, with an average of 5.6 alleles and 2.83 effective alleles, the Shannon 's information index was 1.12, and the Ne's gene diversity index was 0.566. The population structure and linkage disequilibrium (LD) of the tested materials were analyzed by 40 pairs of SSR markers, after conditional filtration with gene frequency of 0.05, there was significant linkage disequilibrium in some of the SSR polymorphism markers. When P < 0.05, eight markers were found to be associated with five quality traits such as SS, titratable acid content (TA), Chl, dry matter (DM) and soluble solids content (SSC). While when P < 0.01, only a significant correlation was found between the marker A193 and SS. In this study, the relative stable markers associated with the inner quality of wild A. eriantha fruit were excavated, and specific allelic variations were established between phenotypes and genotypes. The results could lay a theoretical foundation for the breeding and genetic improvement of novel varieties of A. eriantha in the future.
As one of the most recently domesticated fruit crops, tremendous genetic resources exist in genetic pools of germplasm repositories and in breeding projects as well as in the wild. This chapter focuses on a wide spectrum of genetic resources that are more important to genetic enhancement for germplasm innovation, breeding practice, and new cultivar development, including species diversity, gender diversity, and genetic variation of important fruit characteristics. Ploidy variation is discussed in Chap. 5.
Actinidia (kiwifruit) vary in peeling behavior from “difficult to peel” to “easy to peel.” Thus, the breeding of new cultivars of commercially acceptable kiwifruit with peelable skins is possible. Identification of skin properties conferring peelability and development of a simple, repeatable method for measuring peelability will be critical to the success of breeding programs. We assessed mechanical and biological characteristics of kiwifruit skins with respect to the ease with which fruit could be peeled. Values for skin–flesh adhesion, skin compliance in tension, and skin tearing were obtained, and a simple method for quantifying peelability developed based on knowledge of tearing of sheet materials. Using this test, we established that peelability varies among kiwifruit selections, but is only evident once fruit has ripened. We demonstrated that efficiency of peeling was dependent on the radius of curvature from which the skin is drawn away from the flesh.
The development of a peelable kiwifruit will enhance the diversity of products in the kiwifruit category and provide consumers with a more convenient option for eating this type of fruit. The information presented in this study contributes to the knowledge of the biological, structural and mechanical properties that influence skin-to-flesh adhesion and skin tearing behavior. The simple protocol for assessing peelability may be adapted for use in screening seedling populations for this trait.
Fruit skins perform similar functions to artificial packaging, protecting and identifying the product. Ideally, this packaging should allow easy access to the product, that is the fruit flesh. However, skins of commercial kiwifruit are relatively unpalatable and unpeelable, and thus kiwifruit is not perceived as a convenient product. Observation of fruit of many members of the genus Actinidia has shown that relatives of the kiwifruit have a wide range of fruit skin characteristics that include both thin edible skins and thicker peelable skins. Thus in the fruit of A. arguta, the skin comprises a relatively thin walled epidermis above a one to two cell hypodermis that is easily eaten whilst in A. eriantha skin structure is a much more complex structure of hairs, collapsed and uncollapsed suberised dead cells, and multiple layers of thick walled collenchyma-like hypodermal cells. Fruit of A. chinensis and A. indochinensis consistently show a zone of stone cells below the skin. The ability to peel the skin from the flesh does not appear to be associated with any specific structural features but does appear to be associated with differences in localisation of pectins in the flesh.
Immunolabelling is a powerful technique that can visualise the spatial and temporal arrangement of polysaccharides within plants, providing detail of localisation within tissues, cell types and individual cell walls not obtainable through chemical extraction methods. An increasing number of highly characterised antibodies to cell wall antigens are now becoming available. When using any of these antibodies there is a need for careful interpretation of the labelling patterns, and adequate controls to ensure specific labelling. This review examines some of the issues involved in obtaining meaningful results based on examples from our own work. We focus in particular on immunolabelling of fixed resin embedded material, providing a basic protocol and illustrating the results that can be obtained using it. We also review precautions that must be taken to verify that the results obtained are meaningful and how to troubleshoot if things go wrong. © 2009 New Zealand Forest Research Institute Limited, trading as Scion.
Kiwifruit (Actinidia spp.) are a relatively new, but economically important crop grown in many different parts of the world. Commercial success is driven by the development of new cultivars with novel consumer traits including flavor, appearance, healthful components and convenience. To increase our understanding of the genetic diversity and gene-based control of these key traits in Actinidia, we have produced a collection of 132,577 expressed sequence tags (ESTs).
The ESTs were derived mainly from four Actinidia species (A. chinensis, A. deliciosa, A. arguta and A. eriantha) and fell into 41,858 non redundant clusters (18,070 tentative consensus sequences and 23,788 EST singletons). Analysis of flavor and fragrance-related gene families (acyltransferases and carboxylesterases) and pathways (terpenoid biosynthesis) is presented in comparison with a chemical analysis of the compounds present in Actinidia including esters, acids, alcohols and terpenes. ESTs are identified for most genes in color pathways controlling chlorophyll degradation and carotenoid biosynthesis. In the health area, data are presented on the ESTs involved in ascorbic acid and quinic acid biosynthesis showing not only that genes for many of the steps in these pathways are represented in the database, but that genes encoding some critical steps are absent. In the convenience area, genes related to different stages of fruit softening are identified.
This large EST resource will allow researchers to undertake the tremendous challenge of understanding the molecular basis of genetic diversity in the Actinidia genus as well as provide an EST resource for comparative fruit genomics. The various bioinformatics analyses we have undertaken demonstrates the extent of coverage of ESTs for genes encoding different biochemical pathways in Actinidia.
Vitamin C (L-ascorbic acid, AsA) is an essential metabolite for plants and animals. Kiwifruit (Actinidia spp.) are a rich dietary source of AsA for humans. To understand AsA biosynthesis in kiwifruit, AsA levels and the relative
expression of genes putatively involved in AsA biosynthesis, regeneration, and transport were correlated by quantitative polymerase
chain reaction in leaves and during fruit development in four kiwifruit genotypes (three species; A. eriantha, A. chinensis, and A. deliciosa). During fruit development, fruit AsA concentration peaked between 4 and 6 weeks after anthesis with A. eriantha having 3–16-fold higher AsA than other genotypes. The rise in AsA concentration typically occurred close to the peak in expression
of the L-galactose pathway biosynthetic genes, particularly the GDP-L-galactose guanyltransferase gene. The high concentration of AsA found in the fruit of A. eriantha is probably due to higher expression of the GDP-mannose-3′,5′-epimerase and GDP-L-galactose guanyltransferase genes. Over-expression of the kiwifruit GDP-L-galactose guanyltransferase gene in Arabidopsis resulted in up to a 4-fold increase in AsA, while up to a 7-fold increase in AsA was observed in transient expression studies
where both GDP-L-galactose guanyltransferase and GDP-mannose-3′,5′-epimerase genes were co-expressed. These studies show the importance of
GDP-L-galactose guanyltransferase as a rate-limiting step to AsA, and demonstrate how AsA can be significantly increased in plants.
Protocols were developed for regeneration and Agrobacterium-mediated transformation of Actinidia eriantha Benth. A. eriantha has a number of features that make it a useful tool for functional genomics in Actinidia: the vines are relatively small and non-vigorous in nature, flowers form all over the vine including on lower axillary branches and the species flowers prolifically in greenhouse conditions. Flowering and fruiting of transgenic A. eriantha plants was obtained within 2 years of transformation in a containment greenhouse. GUS (beta-glucuronidase) activity indicating stable expression of the uidA gene was observed in leaf, stem, root, petal and fruit tissues. Molecular evidence for incorporation of transgenes into the A. eriantha genome was obtained by PCR and DNA gel blot analysis. Inheritance of transgenic phenotypes was demonstrated in seedling progeny. Functional genomic studies in kiwifruit have been initiated using transgenic A. eriantha plants.
The gene for one postulated enzyme that converts GDP-l-galactose to l-galactose-1-phosphate is unknown in the l-galactose pathway of ascorbic acid biosynthesis and a possible candidate identified through map-based cloning is the uncharacterized gene At4g26850. We identified a putative function for At4g26850 using PSI-Blast and motif searching to show it was a member of the histidine triad superfamily, which includes d-galactose uridyltransferase. We cloned and expressed this Arabidopsis gene and the homologous gene from Actinidia chinensis in Escherichia coli and assayed the expressed protein for activities related to converting GDP-l-galactose to l-galactose-1-P. The expressed protein is best described as a GDP-l-galactose-hexose-1-phosphate guanyltransferase (EC 2.7.7.), catalyzing the transfer of GMP from GDP-l-galactose to a hexose-1-P, most likely d-mannose-1-phosphate in vivo. Transient expression of this A. chinensis gene in tobacco leaves resulted in a >3-fold increase in leaf ascorbate as well as a 50-fold increase in GDP-l-galactose-d-mannose-1-phosphate guanyltransferase activity.
• GDP-l-galactose pyrophosphorylase
• gold kiwifruit
• VTC2
Why is it that bulk sales of apples are many times bigger than of oranges while the reverse holds true for orange juice relative to apple juice? Clearly other factors than liking and price are at play - both fruits are well-liked and similarly priced. Consumers' demand for convenience is the most likely reason and also a key reason why sales of easy-peel citrus fruit are booming compared to traditional cultivars. This article takes a closer look at the convenience phenomenon and argues its importance as a key driver in horticultural product innovation.
The world market for kiwifruit is tiny compared with those for other fresh fruits such as apples and bananas. Although the kiwifruit is a beautiful and nutritious fruit, the present commercial cultivars have some deficiencies that limit the volume and value of the market and the profitability of producers. The extensive genetic variation within the genus Actinidia presents breeders with a wide range of opportunities for developing new products. The challenge for breeders is to identify those improvements that will have the greatest impact on profitability and to devise methods and strategies to overcome technical constraints to achieving them. Breeders need to consider the likely future needs of consumers and producers. They need to have an understanding of the market and of production systems and cost structures. Breeders need access to a diverse germplasm collection and the imagination to foresee the potential of the genetic variation within it. They need to take account of the technical feasibility of their objectives. Choice of parents, especially males, is difficult and ploidy differences can restrict crossing options. The long generation time is a major constraint. The accumulation of tested parents, an improved understanding of the nature and inheritance of key characteristics and the introduction of new techniques can help to reduce or overcome many of these constraints. There are still very few different types of kiwifruit available on the world market and so plenty of opportunities for new types with the right characteristics. With imagination, robust objectives, sound strategies, perseverance and good luck, breeders have the opportunity to breed new cultivars that could help to transform kiwifruit into a mainstream and highly profitable fresh fruit category.
Screening of fruit for oxalate crystals by tissue clarification from 132 genotypes of 15 species of Actinidia vines showed bundles of long raphides in locules that varied in abundance between species. Actinidia macrosperma contained very few raphides in the locules but its seed were packed with raphides. A. eriantha was the other extreme having fruit locules with many raphides. Total oxalate and ascorbate was measured in 134 siblings in an Actinidia chinensis mapping population and this revealed a 4.6 fold variation in oxalate amount (12-55 mg oxalate/100 g fresh weight (FW) and a 4.1 fold variation in ascorbate amount (51-211 mg ascorbate/100 g). We found no correlation between the amounts of oxalate and ascorbate, which supports the hypothesis that if oxalate derives from ascorbate then it is by a regulated process. The results also show that it is possible to select for low fruit oxalate and high ascorbate. Oxalate from three genotypes of A. chinensis and one each of A. deliciosa and A. eriantha was measured in flower buds, flowers, fruits and leaves, at different stages of development. Oxalate was highest in fruit at 1 week after anthesis (WAA) and declined during fruit development to reach its lowest amount in mature fruit (15-21 mg/100 g FW). Oxalate amounts were up to 46 times higher in leaves than in fruit A. eriantha mature leaves showed oxalate amounts up to 1588 mg/100 g FW. The high oxalate content of leaves supports the notion that oxalate may serve a defensive role and/or calcium storage function to regulate soluble calcium concentration in the plant 479-484 Oxalate and Ascorbate in Actinidia Fruit and Leaves M. Rassam S.M. Bulley W.A. Laing The Horticulture and Food Research Institute of New Zealand Ltd. (HortResearch) Private Bag 92 169, Auckland New Zealand raphides, HPLC, kiwifruit, leaves, vitamin C, ascorbate Screening of fruit for oxalate crystals by tissue clarification from 132 genotypes of 15 species of Actinidia vines showed bundles of long raphides in locules that varied in abundance between species. Actinidia macrosperma contained very few raphides in the locules but its seed were packed with raphides. A. eriantha was the other extreme having fruit locules with many raphides. Total oxalate and ascorbate was measured in 134 siblings in an Actinidia chinensis mapping population and this revealed a 4.6 fold variation in oxalate amount (12-55 mg oxalate/100 g fresh weight (FW) and a 4.1 fold variation in ascorbate amount (51-211 mg ascorbate/100 g). We found no correlation between the amounts of oxalate and ascorbate, which supports the hypothesis that if oxalate derives from ascorbate then it is by a regulated process. The results also show that it is possible to select for low fruit oxalate and high ascorbate. Oxalate from three genotypes of A. chinensis and one each of A. deliciosa and A. eriantha was measured in flower buds, flowers, fruits and leaves, at different stages of development. Oxalate was highest in fruit at 1 week after anthesis (WAA) and declined during fruit development to reach its lowest amount in mature fruit (15-21 mg/100 g FW). Oxalate amounts were up to 46 times higher in leaves than in fruit. A. eriantha mature leaves showed oxalate amounts up to 1588 mg/100 g FW. The high oxalate content of leaves supports the notion that oxalate may serve a defensive role and/or calcium storage function to regulate soluble calcium concentration in the plant.
Over the past 10 years, there has been considerable interest in identifying new product opportunities for kiwifruit. Consumer research has contributed to this through the identification of attributes that promote and inhibit kiwifruit consumption. Research has considered consumers' beliefs, attitudes and perceptions of fruit in general, and the impact of flavour, appearance and novelty on preferences and willingness to buy kiwifruit. Sensory panels have been used to establish flavour profiles for a wide range of genotypes, and consumer preference mapping to identify opportunities for new flavours. The studies illustrate that fruit breeding should target not only elite fruit that are significantly more liked than existing cultivars, but also special, unique fruit that create major new flavour niches. Barriers to consumption of kiwifruit often relate to convenience including how to judge when the fruit is ready to eat, and the need for utensils to cut and scoop out the flesh. Novelty can be an advantage or a disadvantage depending on the attitudes of consumers to eating new foods (i.e., whether or not they fear new foods or seek variety in their diet). In studies using experimental markets, consumers paid a significant amount of money to exchange green-fleshed 'Hayward' for a novel redfleshed 'Hongyang' kiwifruit. Results from these studies are discussed in relation to the mega-trends of health, convenience and pleasure that are driving food innovation.
In an attempt to develop a kiwifruit high in nutritional value we raised seedlings of Actinidia eriantha in 1997. In total, 840 seedlings were planted in 1998 at Haenam, Korea. From this F1 population, plant #308 was selected for its better flavour and excellent nutrient content; this selection was named 'Bidan' in 2002. The cultivar 'Bidan' has very high vitamin C and mineral content compared to the standard A. deliciosa cultivar 'Hayward'. In spring, 'Bidan' breaks bud in mid March and starts flowering in late May or early June. Its flowers are dark pink on white coloured twigs. Harvest period is around mid October, when average fruit weight is 25 g, soluble solids content at harvest is 7% and 15-16% after ripening. There are 800-1200 seeds per fruit.
Fruit softening during ripening involves a coordinated series of modi. cations to the polysaccharide components of the primary cell wall and middle lamella, resulting in a weakening of the structure. Degradation of polysaccharides and alterations in the bonding between polymers cause an increase in cell separation and a softening and swelling of the wall, which, combined with alterations in turgor, bring about fruit softening and textural changes. A wide range in the extent of cell wall pectic modi. cations has been observed between species, whereas the depolymerisation of xyloglucan is relatively limited and more consistent. The earliest events to be initiated are usually a loss of pectic galactan side chains and the depolymerisation of matrix glycans, which may begin before ripening, followed by a loss of pectic arabinan side chains and pectin solubilisation. The depolymerisation of pectins may begin during early to mid-ripening, but is usually most pronounced late in ripening. However, some of these events may be absent or occur at very low levels in some species. Cell wall swelling may be related to a loosening of the xyloglucan-cellulose network and to pectin solubilisation, and these processes combined with the loss of pectic side chains increase wall porosity. An increase in wall porosity later in ripening may allow increased access of degradative enzymes to their substrates.
Callus was induced from the fruit galls of Actinidia polygama and the regenerated plants from the callus tissue were cultured. The formation of triterpenoids in the callus was confirmed. Eight triterpenoids containing two new ones were isolated from the callus. The triterpenoid composition found in the callus tissue was compared with those in the regenerated and natural plants. The differences in the metabolic ability of the callus tissue and regenerated plants are also discussed.
Changes in mRNA levels for the seven gene homologues to endoxyloglucan transferase-related protein, expansin, extensin, β-1,3
glucanase, glycine-rich protein, pectinacetylesterase and pectinesterase, which were obtained by random sequencing studies,
were investigated in relation to rind development in citrus (Citrus unshiu Marc.) fruit. Expression patterns in the albedo and flavedo were classified into four types: Type-I, transcript levels low
in early fruit development but increased at the ripening stage; Type-II, transcript levels high until mid-development and
then decreased towards ripening; Type-III, detectable transcript limited to fruitlets at 26 days after flowering (DAF); Type-IV,
ubiquitous during the development. Based on the expression patterns, we discuss the possible roles of these genes in rind
development.
Xyloglucan endotransglucosylase/hydrolase (XTH) enzymes are thought to play a key role in fruit ripening by loosening the cell wall in preparation for further modification by other cell wall-associated enzymes and through disassembly of xyloglucan. Twenty-five XTH genes were isolated and characterised from kiwifruit and apple databases containing >270,000 expressed sequence tags (ESTs). The XTH genes (14 from kiwifruit, 11 from apple) encoded putative proteins with similar molecular weights, but with isoelectric points ranging from acidic to basic. All 25 XTH amino acid sequences contained the two conserved glutamic acid residues at the active site of the XTH enzyme. Phylogenetic analysis produced trees with branches each containing kiwifruit, apple, tomato and Arabidopsis XTH sequences, suggesting the potential for functional orthology. EST expression profiling and quantitative PCR analysis were used to identify kiwifruit and apple XTH transcripts expressed in root tip, flower, young leaf and ripe fruit. In ripe apple fruit, the transcripts for two XTH genes (Md-XTH2 and Md-XTH10) were the most abundant, whilst in ripe kiwifruit three transcripts predominated (Ad-XTH4, 5 and 7). Ad-XTH7 was highly expressed in the outer pericarp of firm kiwifruit at commercial harvest and expression of this mRNA decreased during the rapid softening phase. Three kiwifruit XTH genes (Ad-XTH5, Ad-XTH7 and Ac-XTH14) were expressed in Escherichia coli and the recombinant proteins were shown to have xyloglucan endotransglucosylase activity. This research lays the groundwork for understanding the role of XTHs during fruit ripening and storage in kiwifruit and apple.
During experiments characterizing and identifying proteins from controlled atmosphere-stored apple and peach fruit, we optimized methods for the extraction and two-dimensional electrophoresis (2-DE) of fruit proteins, using commercially available immobilized pH gradient strips for the first dimension. The method is relatively rapid with minimal handling of small amounts of sample, and has been reproduced successfully for 2-DE of a variety of fruit and plant tissues in our labs. Critical factors for fruit tissues include using acetone precipitation following incubation in a lysis buffer, and a long iso-electric focussing time. We have observed no interference to focussing from such troublesome fruit components as soluble pectins, polyphenolics, or high-acidity fruit, using this protocol. In addition we have used the method with no modification, for a range of fruit tissues including low protein sources (apple and peach flesh), high lipid material (avocado fruit flesh) and high acidity lemon tissue. As the method in our hands is straightforward and robust, we recommend the method for routine 2-DE separations of fruit samples.
A number of commonly consumed fruits and vegetables (e.g., kiwifruit, pineapple and taro) cause oral irritation, and there is anecdotal evidence that this influences the acceptability of such products. In each of these foods, oral irritation is produced by free crystalline calcium oxalate (raphides). The psychophysics of the mechanical oral irritation caused by raphides was studied in two experiments using a model system based on kiwifruit. In the first experiment, the location of irritant sensations and perceived intensity of the irritation caused by suspensions of raphides were determined using a ten-member trained sensory panel. Stinging and numbing were found to increase significantly with increasing concentrations of raphides. Stinging occurred principally on the tongue as well as in the throat and numbing principally on the tongue. 7he number of oral areas irritated was shown to increase with raphide concentration and to decrease over a 60-min period. In the second experiment, sugars (fructose, sucrose, glucose and inositol), acids (citric, malic and quinic) and an enzyme (actinidin) were added to the model to examine interactions between these chemical stimuli and the mechanical action of the raphides. Addition of acids to the model was shown to enhance irritation in addition to increasing sourness and suppressing sweetness. The addition of actinidin had no significant effects on irritation or tastes. It is suggested that acidity may aggravate irritation at low raphide concentration, but beyond a critical level of mechanical irritation the presence of acids has little additional effect. These results provide the first detailed data of the psychophysics of mechanical oral irritation in food, and have important implications for producing foods with lower levels of irritation and increased acceptability.
A new method for determination of uronic acids with meta-hydroxydiphenyl is introduced. It is simpler, quicker, more sensitive, and more specific than other methods, and it needs lesser amounts of fluid. It is recommended for determination of acid mucopolysaccharides in biological materials.
Transcript abundance of the gene encoding beta-galactosidase II, a beta-galactosidase/exo-galactanase (EC 3.2.1.23) present during tomato (Lycopersicon esculentum) fruit ripening, was suppressed by expression of an antisense tomato beta-galactosidase 4 (TBG4) cDNA driven by the cauliflower mosaic virus 35S promoter. RNA gel-blot analysis was used to evaluate TBG4 mRNA levels in transgenic fruit. All of the antisense lines had attenuated TBG4 mRNA levels in turning stage fruit; however, TBG4 mRNA suppression was unstable, and mRNA levels varied in red-ripe fruit among the lines. Suppression of TBG4 mRNA levels in antisense fruit was correlated with a reduction in extractable exo-galactanase activity against a lupin galactan. All of the antisense lines had reduced free galactose levels at mature green stage 4, but levels comparable with controls during ripening. Total cell wall galactosyl contents in the antisense fruit were not significantly different from control fruit. Whole-fruit firmness was measured using a texture analyzer and the means of the peak force measurements for four of six antisense lines were significantly higher than control fruit. One antisense line had red-ripe fruit that were 40% firmer than controls. Fruit from this antisense line also had the lowest TBG4 mRNA and exo-galactanase levels and the highest wall galactosyl content during the early stages of ripening, implicating an involvement of this gene product in cell wall modification leading to fruit softening.
Oleanolic acid and ursolic acid are ubiquitous triterpenoids in plant kingdom, medicinal herbs, and are integral part of the human diet. During the last decade over 700 research articles have been published on their research, reflecting tremendous interest and progress in our understanding of these triterpenoids. This included the isolation and purification of these tritepernoids from various plants and herbs, the chemical modifications to make more effective and water soluble derivatives, the pharmacological research on their beneficial effects, the toxicity studies, and the clinical use of these triterpenoids in various diseases including anticancer chemotherapies. A briefly commentary is attempted here for their research perspectives.
With the increasing prevalence of allergies, accurate identification of allergens is a major priority for allergists, scientists, the food industry, and food regulators. Knowledge of allergens is essential for risk assessment of novel genetically modified (GM) foods, and to develop recombinant proteins for the treatment and diagnosis of allergies. This Opinion Paper considers the lack of standardization for the clinical and scientific assessment of proteins before they are labelled as allergens. Food allergens are being reported and recorded in allergen databases, with minimal or in some cases apparently no published justification. IgE binding, rather than clinically relevant reactivity, is inappropriately used to confirm allergenicity. Using kiwifruit as an example, the lack of rigor in identifying allergenic proteins is considered.
Purifi cation and some properties of protease from Actinidia eriantha Benth
- C Liang
- S Li
- Z Yang
Liang, C., Li, S., & Yang, Z. (1999). Purifi cation and
some properties of protease from Actinidia
eriantha Benth. Journal of Plant Resources
and Environment, 8, 1-6.
The selection and breeding for new ornamental varieties of Actinidia
- S M Wang
- R H Huang
- X W Wu
- N Kang
- H Q Huang
Wang, S. M., Huang, R. H., Wu, X. W., Kang, N., &
Huang, H. Q. (1993). The selection and
breeding for new ornamental varieties of
Actinidia. Journal of Fruit Science, 10, 116-118.
Isolation and identifi cation of two new triterpenes from Actinidia eriantha
- C Huang
- Z Zhang
- G Li
- J Zhou
Huang, C., Zhang, Z., Li, G., & Zhou, J. (1988). Isolation
and identifi cation of two new triterpenes from
Actinidia eriantha. Acta Botanica Yunnanica,
10, 93-100.