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Pollination: Self-fertilization strategy in an orchid

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Abstract

Mating in flowering plants normally relies on animals, wind, gravity or secretion to convey pollen grains from the male (anther) to the female (stigma) organ. Here we describe a new type of self-pollination mechanism in the tree-living orchid Holcoglossum amesianum, in which the bisexual flower turns its anther against gravity through 360 degrees in order to insert pollen into its own stigma cavity - without the aid of any pollinating agent or medium. This mode of self-pollination, which occurs under windless, drought conditions when insects are scarce, adds to the variety of mechanisms that have evolved in angiosperms to ensure their reproductive success.

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... Between 5% and 20% of orchid species have evolved autogamy (Gale, 2007;Pang et al., 2012;Tremblay, Ackerman, Zimmerman, & Calvo, 2005). This mode of autogamy often occurs under windless conditions and in drought and insect-scarce habitats to ensure reproductive success (Liu et al., 2006). ...
... It refers to a pollination system in which unopened flowers are capable of autogamy resulting in fruit productions. This trait is an adaptive mechanism for retaining reproduction under poor growth conditions, such as drought, extreme airflow, and sunlight (Faisal et al., 2018;Liu et al., 2006;Lord, 1981;Zou, Zhou, Angessa, Zhang, & Li, 2018). In a majority of cleistogamous species, closed (cleistogamous, CL) and open flowers (chasmogamous, CH) usually occur on the same individuals during a single flowering season. ...
... Studies on this plant in the wild observed that the rate of fruit set of D. wangliangii was rather high under natural conditions. A common trend of pollinator scarcity is noted under drought conditions (Liu et al., 2006), that may exert selective pressure via pollinator limitations, thus promoting the evolution of autogamy as a reproductive assurance mechanism. Therefore, the reproductive biology of D. wangliangii represents an interesting problem. ...
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Dendrobium wangliangii is an epiphytic orchid distributed in the Jinshajiang dry‐hot valley in Luquan County, Yunnan Province, China. Most Dendrobium spp. typically have a low fruit set, but this orchid shows a higher fruit set under natural conditions despite the lack of effective pollinators. The pollination biology of the critically endangered D. wangliangii was investigated in this study. A fruit set rate of 33.33 ± 4.71% was observed after bagging treatment in 2017 and a high fruit set rate (65.72 ± 4.44% in 2011; 50.79 ± 5.44% in 2017) was observed under natural conditions, indicating that D. wangliangii is characterized by spontaneous self‐pollination. The anther cap blocked the growing pollinium; thus, the pollinium slid down and reached the stigmatic cavity, leading to autogamous self‐pollination. Specifically, 51.50% of 162 unopened flowers (total 257 flowers) of this Dendrobium species under extreme water‐deficit conditions developed into fruits, suggesting the presence of cleistogamy in D. wangliangii. Here, cleistogamy may represent the primary mode of pollination for this orchid. Spontaneous self‐pollination and specific cleistogamous autogamy could represent major adaptions to the drought and pollinator‐scarce habitat in the Jinshajiang dry‐hot valley. Dendrobium wangliangii is an epiphytic orchid distributed in the Jinshajiang dry‐hot valley in Luquan County, Yunnan Province, China. D. wangliangii is characterized by spontaneous self‐pollination and cleistogamy. This is a novel case on cleistogamous autogamy in Dendrobium.
... Mucilage is essential for the shedding or transfer of pollen, especially to bind pollen grains and mediate tube migration into the style [9], and reduce pollen hydration that results in self-incompatibility [10]. However, extant orchid species exhibit a high frequency of selfing [11]. The self-contained pollination mechanism is a possible adaptation to an insectscarce habitat [3]. ...
... D. officinale is a traditional Chinese medicinal herb of ornamental value that has a wide variety of therapeutic uses [20]. The ornate flowers of D. officinale attract the attention of flower visitors and insect pollinators, and this property is closely associated with the abundant stigmatic mucilage [11]. However, the genes involved in the biosynthesis of D. officinale mucilage-based polysaccharides have not been identified. ...
... Dendrobium, one of the largest genera of flowering plants, has evolved a myriad of floral forms to attract pollinators [20]. Self-incompatibility severely impedes sexual propagation of Dendrobium plants [11]. Assembly of complete genomic sequences enables investigation of the chromosomal and genomic factors that have influenced the evolution of self-incompatibility in Dendrobium plants [20]. ...
... One of the evolutionary processes that lead to speciation of this family is the frequently observed transition to spontaneous autogamy (Pedersen and Ehlers, 2000;Bateman, 2001;Charlesworth, 2006). Spontaneous selfpollination is sometimes observed in animalpollinated plants when the environment is subject to changes such as anthropogenic habitat fragmentation (Barrett and Shore, 1989;Eckert et al., 2009) or periods of unfavorable climatic conditions (Liu et al., 2006). This transition has also been recorded in some plants that have migrated to new areas outside their previous range (Catling, 1990;Etcheverry et al., 2003;Barrett et al., 2008). ...
... Among Orchidaceae, autogamous flowers are easy to verify due to morphological changes that eliminate mechanical barriers between male and female structures of the column (Pedersen and Ehlers, 2000;Squirrell et al., 2002;Gale, 2007). Self-pollination may also be caused by proactive or facilitated floral movements (Liu et al., 2006;Claessens and Kleynen, 2011), and it is also sometimes connected with unusual processes such as cryptic pollen germination (Bonatti et al., 2006). Such adaptations may be obligatory and determine spontaneous autogamy as the sole pollination mechanism. ...
... They may take place before anthesis in cleistogamous flowers, such as Epipactis microphylla (Bonatti et al., 2006), or during anthesis in chasmogamous flowers, as in Epipactis helleborine subsp. neerlandica (Pedersen and Ehlers, 2000), Holcoglossum amesianum (Liu et al., 2006) or Ophrys apifera (Darwin, 1877). ...
Article
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The breeding system in Orchidaceae generates many questions about the selfing potential of its representatives. We investigated the ability of spontaneous autogamy of four orchid species: Cephalanthera rubra and Neottia ovata of the Neottieae tribe and Gymnadenia conopsea and Platanthera bifolia of the Orchideae tribe. These species represent diverse specializations of the gynostemium architecture. The self-compatibility and properties of autogamous seeds were determined in a bagging experiment and seed development analysis. After induced autogamy, a high level of fruiting (80-100%) was noted in all of the four study species. C. rubra, N. ovata, and G. conopsea are completely self-compatible, and P. bifolia is suggested to be partially self-compatible. If autogamy occurred, inbreeding depression and resource limitation on seed development appeared only in the two Orchideae species. Independent of flower specialization, both Neottieae species and P. bifolia were completely allogamous, whereas G. conopsea could be facultatively autogamous.
... Flowering plants have developed many mechanisms, such as dioecy, dichogamy, herkogamy, self-incompatibility [2], and flexistyly [3,4], to avoid inbreeding and promote outbreeding. Selfing has many benefits, such as opening up new habitats [5,6], avoiding unresponsive pollinators [7][8][9][10], and automatically transferring genes to offspring [11]. However, these benefits are severely abated because of the high mating costs incurred from the pollen and ovule discounting. ...
... The great diversity of pollination mechanisms in angiosperms is most evident in breeding systems of animal pollination [21]. The changes in pollination environment and pollinator behavior directly affect plant mating [6,9,13]. Natural selection is believed to render the floral structure adaptive to cross-fertilization [22,23]. ...
... The findings not only illustrate the reproductive countermeasure of selfing in the mating system evolution of B. orientale but also extended the significance of our research to the evolution of the mixed mating system. In wild populations, uncertainty in the pollinator environment is normal [9,27,37]. The developmental mechanism of the flower not only promotes crossing but also maximizes the pollinator-mediated crossing and affects partial selfing. ...
... Orchid pollination studies are currently combined with other disciplines and techniques. Six major topics were summarized according to recent research results: (i) arguments on coevolution or asynchronous diversification in relation to deceptive pollination (Tremblay et al., 2005;Ramírez et al., 2007Ramírez et al., , 2011Gaskett, 2011;Schiestl & Dötterl, 2012); (ii) game relationship between deceptive orchids and deceived pollinators (Vereecken & McNeil, 2010;More et al., 2012;Peter & Johnson, 2013;Vereecken et al., 2013); (iii) forces (e.g., mimicry of orchids or perceptual exploitation bias of insects) that drive the diversification and speciation of orchids (Salzmann et al., 2007;Schaefer & Ruxton, 2009;Schiestl, 2010;Schiestl et al., 2010;Ayasse et al., 2011;Schiestl & Johnson, 2013); (iv) phylogenetic evolution of different pollination syndromes (Schlüter & Schiestl, 2008;Inda et al., 2012); (v) rapid adaptation and evolution of orchids in pollinator-scarce habitats (Liu et al., 2006a(Liu et al., , 2008aMicheneau et al., 2008;Chen et al., 2012); and (vi) progenitor-derivative speciation in deceptive orchids (Schlüter et al., 2011;Schnitzler et al., 2011;Xu et al., 2012). ...
... The following five Chinese orchid species exhibit selfpollination: Holcoglossum amesianum (Rchb. f.) Christenson (Liu et al., 2006a), Eulophia graminea Lindl. (Chen et al., 2010), Epipogium roseum (D. ...
... Different species use different selfpollination methods. For example, the bisexual flowers of H. amesianum have anthers that can oppose the direction of gravity by 360°to insert the pollen into its own stigma cavity without any pollinating agent or medium (Liu et al., 2006a). The anther of P. parishii liquefies and directly drops onto the stigma surface without help from any pollinating agent or floral assembly . ...
... Orchid pollination studies are currently combined with other disciplines and techniques. Six major topics were summarized according to recent research results: (i) arguments on coevolution or asynchronous diversification in relation to deceptive pollination (Tremblay et al., 2005;Ramírez et al., 2007Ramírez et al., , 2011Gaskett, 2011;Schiestl & Dötterl, 2012); (ii) game relationship between deceptive orchids and deceived pollinators (Vereecken & McNeil, 2010;More et al., 2012;Peter & Johnson, 2013;Vereecken et al., 2013); (iii) forces (e.g., mimicry of orchids or perceptual exploitation bias of insects) that drive the diversification and speciation of orchids (Salzmann et al., 2007;Schaefer & Ruxton, 2009;Schiestl, 2010;Schiestl et al., 2010;Ayasse et al., 2011;Schiestl & Johnson, 2013); (iv) phylogenetic evolution of different pollination syndromes (Schlüter & Schiestl, 2008;Inda et al., 2012); (v) rapid adaptation and evolution of orchids in pollinator-scarce habitats (Liu et al., 2006a(Liu et al., , 2008aMicheneau et al., 2008;Chen et al., 2012); and (vi) progenitor-derivative speciation in deceptive orchids (Schlüter et al., 2011;Schnitzler et al., 2011;Xu et al., 2012). ...
... The following five Chinese orchid species exhibit selfpollination: Holcoglossum amesianum (Rchb. f.) Christenson (Liu et al., 2006a), Eulophia graminea Lindl. (Chen et al., 2010), Epipogium roseum (D. ...
... Different species use different selfpollination methods. For example, the bisexual flowers of H. amesianum have anthers that can oppose the direction of gravity by 360°to insert the pollen into its own stigma cavity without any pollinating agent or medium (Liu et al., 2006a). The anther of P. parishii liquefies and directly drops onto the stigma surface without help from any pollinating agent or floral assembly . ...
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Orchid pollination and evolution are common topics in evolutionary biology. China has approximately 1400 orchid species distributed in diverse habitats and account for approximately 5% of the orchid species in the world. These orchids provide us with materials to explore coevolution and organic evolution. We summarized 53 Chinese orchid pollination studies and synthesized their main findings and common patterns. Bees and flies are the main pollinators of Chinese orchids and drive the diversification of Paphiopedilum and Cypripedium. In addition, the patterns are consistent with phylogenetic evolution studies. Almost half of the Chinese orchids use a common fooddeceptive pollination strategy to transfer their pollens. Other orchids use Batesian mimicry, brood‐site imitation, and green‐leaf volatile imitation, which is rare. Holcoglossum amesianum (Rchb. f.) Christenson and Paphiopedilum parishii (Rchb. f.) Stein, which live in insect‐scarce habitats, use self‐pollination strategies to ensure their reproductive success. However, studies on pollination are in the early stages and comprehensive studies are scarce. Therefore, future studies should involve additional disciplines and techniques, such as chemecologic, electrophysiologic, genomic, transcriptomic, and proteomic methods, to evaluate the floral features that attract specific pollinators and to elucidate the patterns of Chinese orchid pollination, evolutionary history, diversification, and speciation between orchids and their pollinators.
... Flowering orchids could undergo self-pollination due to the extreme environmental conditions signified there was a very rare possibility for a cross-fertilization by insects in these ecological marginal areas to occur. Self-fertilization is an evolution strategy adapted by monoecious (male and female reproductive organs in the same individual) orchid species to increase the chances of producing sterile seeds during unfavourable conditions (Stebbins, 1957;Piper et al., 1984;Liu et al., 2006). This mode of pollination occurs under windless, drought conditions when insects are scarce to ensure the plant's reproductive success (Wang et al., 2004, Liu et al., 2006. ...
... Self-fertilization is an evolution strategy adapted by monoecious (male and female reproductive organs in the same individual) orchid species to increase the chances of producing sterile seeds during unfavourable conditions (Stebbins, 1957;Piper et al., 1984;Liu et al., 2006). This mode of pollination occurs under windless, drought conditions when insects are scarce to ensure the plant's reproductive success (Wang et al., 2004, Liu et al., 2006. However, this adaptation is not applicable to dioecious (male and female reproductive organs in separate individuals) plants. ...
Article
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Monitoring the impact of anthropogenic and naturogenic threats on orchid community through diversity, taxonomy and conservation studies is necessary. Reintroduction of these species to their natural habitat associates with their resilience, selection of suitable trees and sites for regeneration and restoration efforts, drives the conservation initiative. Upon obtaining an accurate estimate of the diversity for genetic resource conservation, integrative methods of classical morphological taxonomy, anatomy (micromorphology), and molecular genetics are crucial to solve the taxonomic uncertainty. Changes in microclimatic conditions and habitat structures are the key determinants of both epiphytic and terrestrial orchids assemblages following disturbance. Any assessments of biodiversity and ecosystem service must include variable forest types and management regimes to provide impartial views on the effect of forest and ecological disturbance on the orchid community. Accordingly, a plant-microbial ecology study should be included to study the extent of human-induced climatic variability towards the orchid diversification.
... Whole of the process is done by the presence of powdery pollinia and disfigure of the column. In Holcoglossum amesianum the anthers are direction of gravity by 360 • and the pollen can comes into by the stigma cavity (Liu, et al. 2006) . In autopllination it is noted that these are insert scarcehabitats (Chen ,et al .2012;Liu, ...
... the lack of pollinators. Whole of the process is done by the presence of powdery pollinia and disfigure of the column. In Holcoglossum amesianum the anthers are direction of gravity by 360 • and the pollen can comes into by the stigma cavity (Liu, et al. 2006) . In autopllination it is noted that these are insert scarcehabitats (Chen ,et al .2012;Liu, et al. 2006 ) . Nectar :-The mixture of water and diluted sugar . It can be produce in the increase of flowering visiting movements . It is the main source of the pollination (Pijl&Dodson1966) . The Structure of the Nectar gland can be found different parts of Oncidinae or simple or either it was different in one species to another species (Pansari ...
Article
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The main purpose of this communication is to review various types of pollination mechanisms involved in orchid species. The Bees and wasp (Male Wasp) are common type of Pollinators There are secondary components such as wind, rain, gravity that also work as pollinators. The male wasp gets attracted towards orchid flower and accomplish pollination. The wings and body hairs of the pollinator work as main pollinating components.
... Finally, the most animate strategy adopted by plants is proactive self-fertilization (PSF) in Orchidaceae. During PSF, the pollinarium is inserted into the receptive stigmatic cavity through the programed movement of its stipe (Liu et al., 2006) (Fig. 3i), thus culminating the ODC in plants. In this case, instead relying of external abiotic or biotic factors for pollination, the plant completes pollination through a series of self-driven movements of its own stamens. ...
... In this case, instead relying of external abiotic or biotic factors for pollination, the plant completes pollination through a series of self-driven movements of its own stamens. PSF makes the concerned orchids fully independent of otherwise indispensable pollinating agents during pollination and thus ensures the successful reproduction and continuation of lineage (Liu et al., 2006). Apparently, PSF gives the plant more freedom and control over the whole process of its reproduction. ...
Preprint
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Background All organisms evolve, according to Darwin. The question is how? Is there any general pattern or trend in the organisms’ evolution? These are rarely asked and almost never answered questions. This situation makes the evolution frustrating an d mysterious to many. Results After surveying the reproductive modes in most animals and plants, we propose that all (at least most) of higher organisms demonstrate the similar trend underlying their reproductive evolution, namely, Offspring Development C onditioning (ODC). ODC benefit the organisms in two ways: one is enhanced physical protection, the other is secured nutrition supply. Conclusions This pattern makes the origin and evolution of reproductive organs in both animals and plants rational and co mprehensive . To the best of our knowledge, this pattern appears universal in higher organisms (including both plants and animals), although we encourage future colleagues to identify exceptions. We hope this will help frame the evolution of higher animals and plants, and make their evolution comprehensive to everyone.
... Finally, the most animate strategy adopted by plants is proactive self-fertilization (PSF) in Orchidaceae. During PSF, the pollinarium is inserted into the receptive stigmatic cavity through the programed movement of its stipe (Liu et al., 2006) (Fig. 3i), thus culminating the ODC in plants. In this case, instead relying of external abiotic or biotic factors for pollination, the plant completes pollination through a series of self-driven movements of its own stamens. ...
... In this case, instead relying of external abiotic or biotic factors for pollination, the plant completes pollination through a series of self-driven movements of its own stamens. PSF makes the concerned orchids fully independent of otherwise indispensable pollinating agents during pollination and thus ensures the successful reproduction and continuation of lineage (Liu et al., 2006). Apparently, PSF gives the plant more freedom and control over the whole process of its reproduction. ...
Preprint
Full-text available
All organisms evolve, according to Darwin. The question is how? Is there any general pattern or trend in the organisms’ evolution? These are rarely asked – and almost never answered – questions. This situation makes the evolution frustrating and mysterious to many. Here, after surveying the reproductive modes in most animals and plants, we propose that all (at least most) of higher organisms demonstrate the similar trend underlying their reproductive evolution, namely, Offspring Development Conditioning (ODC). Such a pattern makes the origin and evolution of reproductive organs in both animals and plants rational and understandable. To the best of our knowledge, this pattern appears universal, although we encourage future authors to identify exceptions. We hope this will help frame the evolution of higher animals and plants, and make the latter understandable to the public.
... Evidence from observations of flowers at two sites, as well as flowers sampled from pressed herbarium specimens, suggests that autonomous self-pollination occurs frequently, and in populations from across the species' range. Although self-pollination is thought to be relatively common in orchids (Catling, 1990;Liu et al., 2006), this is the first evidence for autonomous selfpollination in Satyrium: Autonomous self-pollination has not been reported for any of the 32 taxa (c. one-third of the entire genus) of which flowers have been inspected in previous pollination studies (Garside, 1922;Johnson, 1996Johnson, , 1997aJohnson, , 1997bJohnson et al., 2007;Johnson et al., 2011;Van der Niet et al., 2011;Van der Niet et al., 2015a;Van der Niet et al., 2015b). ...
... Autonomous self-pollination may have been considered unlikely in Satyrium due to both the positioning of anther and stigma in nonresupinate flowers, which prevents gravity-induced autonomous selfpollination (Catling, 1990), and the shape and position of the rostellum which blocks the passage of pollinia to the stigma (Kurzweil, 1996). The mechanism of autonomous self-pollination in S. rupestre involves a combination of the 'bending of the caudicle' and 'rostellum dissolving' mechanisms of autonomous self-pollination described in other orchid species (Catling, 1990;Liu et al., 2006;Van der Niet et al., 2017). Paradoxically, caudicle reconfiguration, which is known to occur in freshly-removed pollinaria of some insect-pollinated Satyrium species (Johnson, 1997a), is usually thought to function as adaptation to outcrossing (Darwin, 1862;Peter and Johnson, 2006). ...
Article
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Autonomous self-pollination is widespread in orchids, but has not yet been reported for Satyrium, a genus in which floral variation is generally associated with attraction of and specialized pollination by a wide range of animals. Here I add evidence for autonomous self-pollination in the diminutive flowers of S. rupestre from the Cape Floristic Region. In recently opened flowers, pollinia of S. rupestre flowers have moved out of the anther sacs and, accompanied by reconfiguration of the caudicles, moved upwards to contact and rest on the stigma. Movement of the pollinia is associated with a narrowed central region of the rostellum, which results from tissue disintegration in flower buds; a process which does not occur in the animal-pollinated sister species S. ligulatum. Evidence of autonomous self-pollination in S. rupestre was observed both in fresh flowers in situ in two populations and in several herbarium specimens collected across the c. 400 km long species range, consistent with autonomous self-pollination as a species-wide trait. Tetrazolium staining tests indicated that more than 50% of seeds produced following self-pollination are viable. Although small amounts of liquid were detected in the spurs of S. rupestre flowers, scent emission rates and the number of massulae per pollinium are consistent with reduced reliance on animal pollinators. Future studies should focus on the extent to which the species relies on autonomous self-pollination for reproduction, to reveal whether it may serve as a mechanism of reproductive assurance in the pollinator-depauperate forest and cliff habitats of S. rupestre.
... Stamen movement refers to situations in which stamens move under their own volition or when they move in response to stimulation by external triggers such as pollinators (Ren 2010). Four main types of stamen movement are recognized (Ren 2010): stimulated (Cota-S anchez et al. 2013); simultaneous and slow (Liu et al. 2006); quick and explosive (Joan et al. 2005); and cascade (Ren and Tang 2012). Slow stamen movement is widespread and is characterized by changes in stamen position, the degree of dichogamy during flowering, and the movement of the anther to a specific area that allows it to directly deliver pollen to recipient stigmas for self-fertilization (Ren 2010). ...
... Over the 10-16-day floral lifespan of Idiospermum australiense, movement of floral organs causes spatial and temporal separation of male and female floral functions (Worboys and Jackes 2005). Similarly, stamen movement has been described to be responsible for the selffertilization mechanism in the tree-living orchid, Holcoglossum amesianum, where the bisexual flower turns its anther 360 , against gravity, to insert pollen into its own stigma cavity, without the aid of any pollinating agent or medium (Liu et al. 2006). Ren and Tang (2012) proposed that stamen movement can determine the fate of pollen. ...
Article
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Approximately 80 % of angiosperm species produce hermaphroditic flowers, which face the problem of male–male sexual interference (one or more anthers gets in the way of disseminating pollen from other anthers) or male–female sexual interference (the pistil interferes with disseminating pollen from the anthers by preventing the anther from touching a pollinator, or the anther prevents pollinator from depositing outcross pollen on the stigma). Slow stamen movement in hermaphrodite flowers has been interpreted as an adaptation for reducing male–male sexual interference. Using slow stamen movement in Lychnis cognata (Caryophyllaceae), this study presents new evidence that this phenomenon can reduce both male–male and male–female sexual interference. Ten stamens in L. cognata flowers vertically elongated their filaments in two batches and displayed similar patterns in pollen dispensing. More importantly, 10 stamens bend out of the floral centre by curving the filament also in 2 batches and pollen grains located at the flower centre displayed the highest viability. Thus, three stages of stamen movement can be identified, comprising two male stages (M1 and M2) and one female stage (F). We found that the main pollinator for L. cognata, Bhutanitis yulongensis (Papilionodae) generally preferred M1 flowers. Manipulation experiments show that vertical stamen movement enabled the anthers to dehisce at different times to prolong the presentation of pollen grains. Horizontal movement of the stamen decreased both male–male and male–female interference. However, vertical stamen movement had a minor role in increasing amount of pollen received by the stigma. This study provides the first direct experimental evidence of concurrent male–male and male–female interference in a flower. We suggest that the selection pressure to reduce such interference might be a strong force in floral evolution. We also propose that other selective pressure, including pollen dispensing mechanisms, pollen longevity, pollinator behaviour and weather, might contribute to floral evolution.
... Biological pollination of C. obcordata was carried out in fields [16,26] until all flowers faded or fruited, and the fruiting rate of natural pollination was calculated statistically. The mating system was investigated as described below at the National Orchid Conservation Center of China. ...
... The mating system was investigated as described below at the National Orchid Conservation Center of China. During the flowering period of C. obcordata, 40 sample sites were set up and 10 flowers from each sample site were tested under the following treatments: (1) flowers were bagged before blooming until all faded or fruited and the fruiting rate was calculated; (2) flowers were bagged before blooming, pollinia were placed on the stigmata after blooming, the flowers were bagged again until all flowers faded or fruited, and the fruiting rate was calculated; or (3) flowers were bagged before blooming, pollinium was placed on the stigmata of flowers from different genets and bagged again until all flowers faded or fruited, and the fruiting rate was calculated [26]. ...
... Despite the inevitable inbreeding depression of offspring due to increased homozygosity of rare recessive deleterious alleles, selfing remains an important mode of mating in plants, accounting for 14% of seed plant species and providing short-term ecological and genetic benefits (Charlesworth and Willis, 2009;van Ginkel and Flipph, 2020). Selfing offers plants an opportunity for reproductive success, especially in the absence of available mates or pollinators, resulting in offspring production, contributing to their adaptability to variations in climate, geography, and reproductive systems (Liu et al., 2006;Hartfield et al., 2017). In this context, selfing can produce differential mutant progeny, which, in turn, increases the opportunity for phenotypic selection among families (McClosky et al., 2013). ...
Article
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Premise The impact of inbreeding on biological processes is well documented in individuals with severe inbreeding depression. However, the biological processes influencing the adaptive growth of normal selfed individuals are unknown. Here, we aimed to investigate how inbreeding affects gene expression for adaptive growth of normal selfed seedlings from a self‐fertilizing parent in Chinese fir ( Cunninghamia lanceolata ). Methods Using RNA‐seq data from above‐ and underground tissues of abnormal and normal selfed seedlings, we analyzed GO biological processes network. We also sequenced small RNAs in the aboveground tissues and measured the copy number variations (CNV) of the hub genes. Results Phenotypic fitness analysis revealed that the normal seedlings were better adapted than their abnormal counterparts. Upregulated differentially expressed genes (DEGs) were associated with development processes, and downregulated DEGs were mainly enriched in fundamental metabolism and stress response. Results of mRNA‐miRNA parallel sequencing revealed that upregulated target genes were predominantly associated with development, highlighting their crucial role in phosphorylation in signal transduction networks. We also discovered a moderate correlation (0.1328 < R ² < 0.6257) between CNV and gene expression levels for three hub genes ( TMKL1 , GT2 , and RHY1A ). Conclusions We uncovered the key biological processes underpinning the growth of normal selfed seedlings and established the relationship between CNV and the expression levels of hub genes in selfed seedlings. Understanding the candidate genes involved in the growth of selfed seedlings will help us comprehend the genetic mechanisms behind inbreeding depression in the evolutionary biology of plants.
... During pollen limitation, due to lower pollinator density, selfing will somehow secure reproductive assurance up to a certain level, as a high selfing rate would lead to inbreeding depression. Thus, selfing traits which promote ovule siring by out-cross pollen first, is more advantageous as evident in Ruta graveolens and Holcoglossum amesianum (Ren and Tang 2012;Liu et al. 2006). This evolution is more beneficial for plants relying on specialists. ...
Article
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The urge to produce progeny and perpetuate is inherent in all species. This instinct of a plant population gets threatened due to population bottlenecks and a reduction in genetic variability among the available mates. Gaining basic pollination and dispersal information is a critical step for understanding the geographical distribution of the species and for predicting the likely impacts of future climate change. Pollination and dispersal attributes, which plant species have adapted over time for favoring a particular type of pollination and dispersal strategy, lead to the co-evolution of species or the establishment of mutualistic interactions. These interactions are dwindling and pose threats to the conservation and reproductive connectivity of populations which proposes the first reason for understanding the advantage of seed dispersal for different endemic, endangered, and threatened taxa.
... R. Ma, Q. Xu, Y. Gao et al. Plant Diversity xxx (xxxx) xxx plants in these areas (Blionis and Vokou, 2001;Totland, 2001;Liu et al., 2006;Wang et al., 2019). Previous studies have also shown that when pollinators are absent, hermaphroditic plants have an advantage over diclinous plants (e.g., Xu et al., 2023). ...
Article
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Sexual systems play important roles in angiosperm evolution and exhibit substantial variations among different floras. Thus, studying their evolution in a whole flora is crucial for understanding the formation and maintenance of plant biodiversity and predicting its responses to environmental change. In this study, we determined the patterns of plant sexual systems and their associations with geographic elements and various life-history traits in dry-hot valley region of southwestern China, an extremely vulnerable ecosystem. Of the 3166 angiosperm species recorded in this area, 74.5% were hermaphroditic, 13.5% were monoecious and 12% were dioecious, showing a high incidence of diclinous species. Diclinous species were strongly associated with tropical elements, whereas hermaphroditic species were strongly associated with temperate and cosmopolitan elements. We also found that hermaphroditism was strongly associated with showy floral displays, specialist entomophily, dry fruits and herbaceous plants. Dioecy was strongly associated with inconspicuous, pale-colored flowers, generalist entomophily, fleshy fruits, and woody plants, whereas monoecy was strongly associated with inconspicuous, pale-colored flowers, anemophily, dry fruits, and herbaceous plants. In addition, hermaphroditic species with generalist entomophily tended to flower in the dry season, whereas diclinous species with specialist entomophily tended to flower in the rainy season. However, independent of sexual systems, plants that produce dry fruits tended to flower in the rainy season and set fruits in the dry season, but the opposite pattern was found for fleshy fruit-producing plants. Our results suggest that in the dry-hot valleys, plant sexual systems are associated with geographic elements as well as various life-history traits that are sensitive to environmental change.
... Generally, orchid flowers are adapted to promote cross-pollination and most species depend on pollen vectors for reproduction [28][29][30][31] . Autogamy is not common in Orchidaceae and this mode of reproduction evolved only in about 5-20% of the family representatives [32][33][34] . ...
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The first comprehensive species distribution models for orchid, its fungal symbionts and pollinator are presented. To evaluate impact of global warming on these organisms three different projections and four various climate change scenarios were analysed. The niche modelling was based on presence-only records of Limodorum abortivum, two species of Russula and three insects pollinating orchid (Anthophora affinis, Bombus terrestris, Rhodanthidium septemdentatum). Two sets of orchid predictions were examined—the first one included only climatic data and the second one was based on climate data and data on future distribution of orchid fungal symbionts. Overall, a poleward range shift is predicted to occur as a result of climate change and apparently global warming will be favorable for L. abortivum and its potential geographical range will expand. However, due to the negative effect of global warming on fungal symbionts of L. abortivum, the actual extension of the suitable niches of the orchid will be much limited. Considering future possibility of cross-pollination, the availability of A. affinis for L. abortivum will decrease and this bee will be available in the worst case scenarios only for 21% of orchid populations. On the other hand, the overlap of orchid and the buff-tailed bumblebee will increase and as much as 86.5% of plant populations will be located within B. terrestris potential range. Also the availability of R. septemdentatum will be higher than currently observed in almost all analysed climate change projections. This study showed the importance of inclusion of ecological factors in species distribution models as the climate data itself are not enough to estimate the future distribution of plant species. Moreover, the availability of pollen vectors which is crucial for long-term survival of orchid populations should be analysed in context of climate changes.
... Many important grain crops such as wheat (Triticum aestivum), rice (Oryza sativa) and soybean (Glycine max) are selfpollinating and do not require vectors such as insects or wind for cross-pollination (Liu et al., 2006). In many legumes and important grass species, self-pollination occurs even before the flower opens (i.e. the pollen is transferred to the stigma of the same flower within the closed flowertermed cleistogamy or pseudocleistogamy; Campbell et al., 1983;Takahashi et al., 2001). ...
Article
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Heat waves occurring during droughts can have a devastating impact on yield, especially if they happen during the flowering and seed set stages of the crop cycle. Global warming and climate change are driving an alarming increase in the frequency and intensity of combined drought and heat stress episodes, critically threatening global food security. Because high temperature is detrimental to reproductive processes, essential for plant yield, we measured the inner temperature, transpiration, sepal stomatal aperture, hormone concentrations and transcriptomic response of closed soybean flowers developing on plants subjected to a combination of drought and heat stress. Here, we report that, during a combination of drought and heat stress, soybean plants prioritize transpiration through flowers over transpiration through leaves by opening their flower stomata, while keeping their leaf stomata closed. This acclimation strategy, termed ‘differential transpiration’, lowers flower inner temperature by about 2–3°C, protecting reproductive processes at the expense of vegetative tissues. Manipulating stomatal regulation, stomatal size and/or stomatal density of flowers could serve as a viable strategy to enhance the yield of different crops and mitigate some of the current and future impacts of global warming and climate change on agriculture.
... Many important grain crops such as wheat (Triticum aestivum), rice (Oryza sativa) and soybean (Glycine max) are selfpollinating and do not require vectors such as insects or wind for cross-pollination (Liu et al., 2006). In many legumes and important grass species, self-pollination occurs even before the flower opens (i.e. the pollen is transferred to the stigma of the same flower within the closed flowertermed cleistogamy or pseudocleistogamy; Campbell et al., 1983;Takahashi et al., 2001). ...
Preprint
Heat waves, occurring during droughts, can have a devastating impact on yield, especially if they happen during the flowering and seed set stages of the crop cycle. Global warming and climate change are driving an alarming increase in the frequency and intensity of combined drought and heat stress episodes, critically threatening global food security. Previous studies revealed that during a combination of drought and heat stress stomata on leaves of many plants are closed, preventing cooling by transpiration. Because high temperature is detrimental to reproductive processes, essential for plant yield, we measured the inner temperature, transpiration, and sepal stomatal aperture of closed soybean flowers, developing on plants subjected to a combination of drought and heat stress. Here, we report that during a combination of drought and heat stress soybean plants prioritize transpiration through flowers over transpiration through leaves by opening their flower stomata, while keeping their leaf stomata closed. This acclimation strategy, termed ‘differential transpiration’, lowers flower inner temperature by about 2-3°C, protecting reproductive processes at the expense of vegetative tissues. Manipulating stomatal regulation, stomatal size and/or stomatal density of flowers could therefore serve as a viable strategy to enhance the yield of different crops and mitigate some of the current and future impacts of global warming and climate change on agriculture. One sentence summary During stress conditions that result in higher flower inner temperature plants use a differential transpiration strategy to protect reproductive processes at the expense of vegetative tissues.
... . According to the 'adaptive plasticity hypothesis,' cleistogamy is favored under heterogeneous and stressful environments (e.g., water deficient and scarce pollinators), which are unsuitable for cross-pollination (Schoen and Lloyd, 1984;Culley, 2002;Albert et al., 2011). Drought conditions may exert selective pressure via pollinator limitations, thus promoting the evolution of autogamy (i.e., CL flowers) as a reproductive assurance mechanism (Liu et al., 2006;Morinaga et al., 2008). Some studies on cleistogamous species have shown that selfing associates more with selection imposed by herbivores than by pollinators, because CH flowers and fruits are more susceptible than CL structures to herbivory (Eckert et al., 2006). ...
Article
Premise of the study: Cleistogamous species constitute interesting study systems to resolve the longstanding question of how outcrossing is maintained given that seed production is assured through selfing. In this work, we investigate the selective forces that allow the persistence of producing self-pollinated cleistogamous (CL) and chasmogamous (CH) flowers in Viola jaubertiana Marès & Vigin. Methods: We monitored three populations at different elevation for two years, and studied the flowering phenology and the relative contribution of each flower morph to parental fitness. We tested whether allocation to CH and CL flowers differed across populations and if it covaried with herbivory and water stress conditions. We also performed hand-pollination and bagging experiments in CH flowers to estimate inbreeding depression and heterosis. Key results: CH flowers open in winter, under unfavorable conditions for pollination, show high pollen limitation and no-delayed selfing, and thus produce a low amount of seeds. Conversely, CL flowers appear in early spring, are physiologically cheaper to produce (i.e. dry weight 3.4 times lower than that of CH flowers), and yield c. 100 times more seeds than CH flowers. CH flowers were favored under water stress and low herbivory. Crosses between populations showed up to 25% greater fitness than those within populations. Conclusions: Despite the great pollen limitation in CH flowers, we suggest that the interaction among different environmental determinants and heterosis are probably sufficient forces to maintain chasmogamy in this long-lived species, reducing deleterious fixed mutations in the selfed lines. This article is protected by copyright. All rights reserved.
... belongs to simultaneous and slow type. Stamen movement of some plants can promote selfpollination, increase the probability of pollination, and facilitate reproduction 46,47 . However, the slow movement of stamens does not promote self-pollination, but supports cross-pollination. ...
Article
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Ziziphus jujuba var. spinosa has been used as a windbreak and for soil conservation and water retention. Previous studies focused on pharmacological effects and extraction of chemical components in this species, and very few explored the breeding system. The present study combined the analysis of floral morphology, behavior of flower visitors, and artificial pollination to reveal reproductive characteristics of the species. Its flowers are characterized by dichogamy, herkogamy, and stamen movement, which are evolutionary adaptations to its breeding system. There were more than 40 species of visiting insects, mainly Hymenoptera and Diptera, and the characteristics of dichogamous and herkogamous flower adapted to the visiting insects. The breeding system is outcrossing, partially self-compatible, and demand for pollinators. The fruit setting rate after natural pollination was 2%. Geitonogamy and xenogamy did not significantly increase the fruit setting rate, indicating that the low fruit setting rate was not due to pollen limitation by likely caused by resource limitation or fruit consumption. The fruit setting rate of zero in emasculated and in naturally and hand self-pollinated individuals suggested the absence of apomixis and spontaneous self-pollination. The above results can be utilized in studies on evolution and cultivation of Z. jujuba var. spinosa.
... Seed abortion is not uncommon in plants. Previous researches have summarized four mainly embryological mechanisms including male sterility [7] caused by anther degeneration [8,9], pollen abortion [10,11] or abnormal tapetum cell structure [9,12,13]; female sterility caused by megasporocyte [14], female reproductive organ or vegetative organ degeneration [15]; poor pollination and/or fertilization which mainly manifested as incompatibility in self-crossing or out-crossing [16][17][18]; and the abortion in the embryonic development process after the formation of the normal zygote [19,20]. Stress from external environment, deficiency of mineral element, uncommon accumulation of endogenous hormone, and the expression of embryo defective genes may fail seed development [7,19,21,22], too. ...
Article
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Research Highlights: The present study firstly reported the metabolic dynamics of astringent seed, a special type of abortion in Chinese fir, during the astringent material stages. The results provide a reference for further study on its occurrence mechanism and enrich the understanding of the plant seed developmental physiology. Background and Objectives: Astringent seed is a type of abortive phenomenon in Chinese fir, which significantly reduces the yield and quality of elite seeds for its high-incidence and indistinguishableness in seed orchard. Embryo defects can be observed in the astringent seed, accompanied with rapid accumulation of secondary metabolites. However, types of those metabolites in astringent seed, dynamic changes during seed growth process, and different accumulative characteristics compared to germinable seed have not been explained. Materials and Methods: Astringent and germinable seed samples were collected at four stages aim to determine the differences in their metabolic patterns. A liquid chromatography-mass spectrometry (LC-MS) detection was used to generate the raw metabolic peaks. Bioinformatics statistical strategies were used to further investigation. Results: A total of 421 metabolites were screened and 112 metabolites were identified as the different expressive metabolites including 68 up-regulated and 44 down-regulated metabolites. Those different expressive metabolites were grouped into 26 classes. Flavone, flavonol, and amino acid derivatives compounds were the most varied metabolites. Four subcategories which could represent the diverse basic expressive patterns or accumulative activity in different sample groups were further clustered. Moreover, pathways related to biosynthesis/degradation/metabolism of flavonoid-like compounds, amino acid/nucleotides derivatives, zeatin, and IAA were clearly enriched. Conclusions: Significant metabolic differences were observed across and between astringent and germinable seeds 105 d after pollination. Massive accumulation of flavonoids-like compounds, significant reduction of amino acids/nucleotides and their derivatives, and the abnormal expression of phytohormones, lipids and other secondary metabolites are the main metabolic characteristics in astringent seeds.
... (e.g. Catling 1990;Liu et al. 2006). However, we did not observe this phenomenon in cultivated Liparis crenulata. ...
Article
Liparis is a large genus comprising ca 300 species, mainly pantropical in distribution. The lips of Liparis flowers, like other members of the subtribe Liparidinae, are downwardly directed and serve as a landing platform for pollinators. The pollination and floral morphology (especially micromorphology) of Liparis are still insufficiently investigated. Field observations have revealed so far that the flowers are visited by small flies, midges, fruit flies, other small dipterans, ants, spiders and mites. However, none of these have been recorded to pollinate these flowers effectively. Preliminary observations revealed the presence of small droplets on the lip surface of Liparis crenulata. As further research revealed, this is the first time that nectar secretion has been recorded in this species. Liquid secretion collected from the lip surface and from whole flowers was subjected to sequential organic solvent extraction and gas chromatography-mass spectrometry (GC-MS). To support our observations, we also investigated floral parts and their role in pollination by means of the scanning electron microscope (SEM) and transmission electron microscope (TEM). The presence of viscid droplets on the lip of Liparis crenulata flowers as well as the presence of a food reward are reported for the first time.
... (e.g. Catling 1990;Liu et al. 2006). ...
Article
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The knowledge about pollination and morphology, especially micromorphology, of the flowers of Liparis species is still sparse and random. The observations of the living plants and their flowers were carried out during the whole period of anthesis. The morphology of floral elements and their potential pollination functions were analyzed. Observations on flower macrostructures were carried out using a light stereoscopic microscope. Additional analyses by scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) were performed. The results of the TEM study revealed secretory activity at dorsal and lateral sepals. Secretory activity has been observed on the whole surface of the lip, thus the function of central lip thickening as a floral attractant and secretion area has been proven. During our study, we had recorded the presence of small droplets on the lip surface of Liparis stricklandiana, what turned out to be the first observation of such type in this species. It seems that the secretion of the lip epidermis occurs in two ways: through the cuticle and through small cracks of the cuticle. Observations made upon the living flowers let confirm the facultative process of self-pollination in Liparis stricklandiana, which occurs at the end of anthesis.
... Some authors (e.g., Muñoz et al. 2010;Walsh and Michaels 2017) suggested that pollination by deceit could reduce the probability of a plant being self-pollinated because the pollinator usually moves away from the flower to avoid being fooled again immediately or because the lack of a reward makes it disinterested in the flower. However, others affirm that self-compatibility might be the result of an adaptation to its pollination syndrome, because accepting its own pollen might raise the chances of being fertilized, although this could affect genetic structure and variation within and among populations (Liu et al. 2006). ...
Conference Paper
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Phragmipedium is a genus with 21 species restricted to the tropics and subtropics from Central and South America. As it is a genus capable of producing seeds from both self-and cross-pollinated flowers, it is an ideal group to investigate the components of its reproductive success. In this research, some of those components are described in P. longifolium as well as anatomical floral structures possibly related to the attraction of pollinators. To study the reproductive system in P. longifolium, manual self-and cross-pollinations were carried out, and seed viability was measured by tetrazolium staining. No significant differences in fruit production between self-and cross-pollinated flowers were found. Higher seed viability was found in the self-pollinated flowers, which indicates that this species is frequently self-pollinated. Sections of the petals of P. humboldtii, P. longifolium, and P. warzewiczianum were stained with toluidine blue in order to identify and characterize anatomical structures possibly involved in the attraction of pollinators. Three kinds of glandular trichomes were observed on the petals of all three species, which are possibly involved in the secretion of fragrances to attract pollinators.
... Some authors (e.g., Muñoz et al. 2010;Walsh and Michaels 2017) suggested that pollination by deceit could reduce the probability of a plant being self-pollinated because the pollinator usually moves away from the flower to avoid being fooled again immediately or because the lack of a reward makes it disinterested in the flower. However, others affirm that self-compatibility might be the result of an adaptation to its pollination syndrome, because accepting its own pollen might raise the chances of being fertilized, although this could affect genetic structure and variation within and among populations (Liu et al. 2006). ...
Conference Paper
Full-text available
Phragmipedium is a genus with 21 species restricted to the tropics and subtropics from Central and South America. As it is a genus capable of producing seeds from both self- and cross-pollinated flowers, it is an ideal group to investigate the components of its reproductive success. In this research some of those components are described in P. longifolium as well as anatomical floral structures possibly related to the attraction of pollinators. To study the reproductive system in P. longifolium, manual self- and cross-pollinations were carried out, and seed viability was measured by tetrazolium staining.
... The mechanical caudicle rotation within flowers of D. fuchsii, similar to that of O. apifera, is opposed to the proactive floral movements against gravity observed in, e.g. Holcoglossum amesianum (Liu et al. 2006). However, in O. apifera, wind is an important final factor, which makes the pollinia swing and touch the stigma because plants placed indoors did not drop any pollinia from the thecae, whereas in the field, over 67% of the pollinia outside the theca adhered to the stigma (Kullenberg 1961;Claessens and Kleynen 2002). ...
Article
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Deceptive plants represent a strategy that promotes outcrossing and protects against facilitated selfing. However, deception does not eliminate the possibility of autonomous self-pollination when pollinators are scarce or absent. Spontaneous autogamy is widespread in Orchidaceae, but the scale, mechanism, time of appearance and effectiveness remain underestimated. Using field and laboratory observations and experiments, for the first time, we documented the possibility of autonomous self-pollination in the deceptive orchid Dactylorhiza fuchsii, which might occur through the previously unspecified mechanism in the tribe Orchideae of caudicle reconfiguration. Self-pollination occurred through the pollinarium twisting to the side and downwards, which was different than caudicle bending forward on the body of pollinators. Caudicle reconfiguration was continuously distributed during anthesis and was common in the studied populations. This mechanism was independent on the flower position in the inflorescence, but was sensitive to pollinator activity. (The frequency of caudicle reconfiguration increased when more pollinaria in the inflorescence were untouched.) This process was effective (self-pollination leading to autogamous fruits and seeds) only when a full caudicle rotation occurred and the pollinium touched the stigma. However, most caudicle reconfigurations were completed before the stigma was reached, resulting in less than 1% of autogamous pollination in the studied populations.
... Movements involved in delayed self-pollination have also been recorded. For instance, the stipe supporting the anthers of the orchid Holcoglossum amesianum can undergo an antigravity 3607 turn that allows insertion of the pollen into the stigmatic cavity (Liu et al. 2006). Similarly, facultative selfpollination occurs in unpollinated Hibiscus trionum when stylar branches curve down and contact anthers of the flowers that have not been visited by pollinators-deposition of pollen on the stigma arrests these movements (Buttrose et al. 1977). ...
Article
Self-fertilization has recurrently evolved in plants, involving different strategies and traits and often loss of attractive functions, collectively known as the selfing syndrome. However, few traits that actively promote self-fertilization have been described. Here we describe a novel mechanism promoting self-fertilization in the Brassi-caceae species Erysimum incanum. This mechanism, which we called “anther rubbing,” consists of autonomous, repeated, and coordinated movements of the stamens over the stigma during flower opening. We have documented anther rubbing by time-lapse videos and experimentally show that it causes self-pollen deposition on stigmas and is sufficient to achieve maximal reproductive output in E. incanum. We predict that these movements should occur in species with limited inbreeding depression, and indeed we find that inbreeding depression in seed production is negligible in this species. While many studies have documented complex floral traits that promote outcrossing, the occurrence of anther rubbing demonstrates that plants can evolve elaborate and underappreciated adaptations to promote self-fertilization.
... There are examples of styles (Buttrose et al., 1977), stigmas (Brauner and Gottlieb, 1987;Freitas and Sazima, 2009) and corollas (Dole, 1990) that move extraordinarily to promote self-pollination. There are still unstudied selfpollination mechanisms, such as ones in which the pollen slides over oil (Wang et al., 2004), pollinia rotate against gravity (Liu et al., 2006), and styles grow discrepantly in relation to stamens (Ma et al., 2012), as well as self-pollination mechanisms combining floral characters and abiotic mechanisms such as wind (Qu et al., 2007) or rain (Fan et al., 2012). ...
Article
Reproduction is key to determine the success of “winner” species. Plants that have an autogamous reproductive system to ensure their reproduction, but which maintain the possibility of cross-pollination, are the most flexible. Here, we aimed at understanding how those mechanisms occur in Sida cordifolia, an introduced pantropical weed. We recorded self-pollination mechanisms, monitored flower anthesis, and carried out a functional morphometric analysis. Based on those data, we established an experimental design of controlled pollination to measure the reproductive success generated by each self-pollination mechanism. We found two spontaneous self-pollination mechanisms: a prior one, during pre-anthesis, and a delayed one, at the moment of flower closure. However, partial dichogamy and herkogamy maintained during anthesis enabled cross-pollination. The floral attributes that maintain these mechanisms are fixed in the population. Alone, self-pollination mechanisms provide half of the fruit production, but together they are comparable to natural and cross-pollination with nearly total success. We show, for the first time, the interaction between prior and delayed self-pollination mechanisms and discuss how their combination enables autogamy but maintains the possibility of cross-pollination. The similar floral morphology of species of the pantropical genus Sida and the diversified self-pollination mechanisms in the family Malvaceae lead us to believe that this process may occur worldwide. Weedy species can be models for studies of floral biology, as they may have unique floral mechanisms that make them “winners” in the context of biotic homogenization.
... There are also an important component of any forest ecosystem with a highly intricate mutual relationship with other biota. This part also attracts insects and other pollinating agents to enable its propagation (Liu et al. 2006). Orchid seeds require syimbiosis by arbuscular-mycorrhizal fungi for germination and depend on this interaction for nutrition into adulthood (McCormick et al. 2018). ...
Conference Paper
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Yogyakarta has unique ecoregions with a high diversity of orchids. Forest in Taman Wisata Alam Curug Setawing (TWACS), Yogyakarta is located in a community protected forest area and keeps a high diversity of orchids. Relative to other plant families, orchids are subject to high levels of threat, such as over-collection, land clearing and climate change. In this study, we describe the diversity of orchids in newly opened tourist areas and their influencing factors and conservation strategies under anthropogenic areas. Ten imaginary plots of 20 m x 20 m each were established randomly by selecting points along the two trail in location. All collected orchids are identified by matching the collection sample with orchid flora books. 15 species of wild orchids can be found in TWACS. Based on subfamily distribution, 73.33% of species including Epidendroideae, 20% Orchidoideae, and 6.66% Vanilloideae. Based on growth form, 46.66% of species belong to epiphytes and 53.33% terestrial orchids. Dendrobium crumenatum has the highest of IVI compared to other species. Zeuxine sp. found only one individual because it is likely to enter the dormancy period. The study reveals that to improve the population size, trees (mainly Albizia chinensis, Syzygium aromaticum, bamboo, Artocarpus heterophyllus, and Albizia saman) should be planted in areas where the orchid species is recently missing through regular inventory.
... No obstante, frente a la incertidumbre de la polinización mediante polinizadores u otros agentes externos, se ha estimado que entre el 1% y el 20% de las angiospermas (Moldenke 1979;Barrett 2002) han desarrollado rasgos que promueven la autogamia de la que dependen y que han venido a definirse como el síndrome de polinización autógama (Sicard y Lenhard 2011). La reproducción autógama es tan esencial para determinadas especies que algunas de ellas han llegado incluso a desarrollar mecanismos activos de autopolinización retardada ante la falta de polinizadores (Liu et al. 2006). Un sofisticado paso más allá en la evolución del síndrome de autogamia ha sido recientemente encontrado en Erysimum incanum, una especie que parece frotar activamente sus anteras sobre el estigma durante la antesis (Abdelaziz et al. datos inéditos). ...
Article
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Pollinators are a key determinant of floral evolution on a global scale. In the Mediterranean area, there are many examples of their role in plant populations of our flora. At the macroevolutionary level, in lineages, there are fewer studies than at population level, but some are illustrative. Both in generalist systems and through some highly specialized interactions, the literature shows us how Mediterranean flowers adapt to pollinators in different ways by developing rewards or modelling their corollas and sexual organs. Hence, global change driven effects on pollinator guilds can have not only ecological, but also evolutionary consequences. Opposing antagonistic forces and other environmental selective factors, pollination interactions have captured the attention of numerous evolutionary biologists in our region.
... One such example is of Holcoglossum amesianum, in which the cap lifts up, pollinia emerges out, takes a complete 360 Ú turn against the gravity and get inserted in own stigma without any external biotic or abiotic agency. This exemplifies high degree of evolution of mechanisms for reproductive assurance in orchids (Fig. 2.) (Liu et al., 2006). ...
... One such example is of Holcoglossum amesianum, in which the cap lifts up, pollinia emerges out, takes a complete 360 Ú turn against the gravity and get inserted in own stigma without any external biotic or abiotic agency. This exemplifies high degree of evolution of mechanisms for reproductive assurance in orchids (Fig. 2.) (Liu et al., 2006). Due to scarcity of pollinators during rains, Acampe rigida, an otherwise deceptive orchid, depends on rain splashes for pollination in order to maintain high fecundity without compromising on chances of xenogamy by visitors (Fan et al., 2012). ...
... Ren (2010) suggested that there are four main types of stamen movement: cascade movement (Weigend and Gottschling , 2006); quick and explosive movement (Taylor et al., 2006); simultaneous and slow movement (Azuma et al., 2005); and stimulated movement (Lechowski and Bialczyk, 1992; Lebuhn and Anderson, 1994). Stamen movement can affect the reproductive biology of fl owering plants because this mechanism forces the visitors to enter fl owers and may alter the interaction plant-pollinator (Schlindwein and Wittmann, 1997; Edwards et al., 2005; Liu et al., 2006; Ren, 2010). ...
Article
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., 2007). Motion occurs in different fl oral parts: corolla, gynoecium, style, stigma, or stamens, and motility is either insect-induced or active (Ruan and Texeira da Silva, 2011). A recent review on adap-tative advantages of fl oral movement indicated four main benefi ts: (1) they promote outcrossing, (2) allow delayed selfi ng, (3) support tolerance to harsh environments, and (4) reduce intrafl o-ral male-female interference (Ruan and Teixeira da Silva, 2011). Investigation of motility of fl oral elements and its adaptive signifi cance allows unders-tanding evolution of mating systems, ecological habitat shifts and pollina-tor environments in different groups of plants (Herlihy and Eckert, 2002; Kalisz
... The usual mechanism of autonomous self-pollination involves the pollinia falling onto the stigma surface, allowing contact between the pollinia and stigma (e.g. Liu et al. 2006, Chen et al. 2012, Suetsugu 2013a, b, c, 2014, but also see Gamisch et al. 2013). However, the autogamous system of G. flexistyloides is notable because the central lobe of the column, which is strongly incurved, also contributes to the pollination process, allowing the anther to contact with stigma directly and thus facilitate selfpollination. ...
Article
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A new species, Gastrodia flexistyloides (Orchidaceae: Epidendroideae, Gastrodieae) from Takeshima Island, Kagoshima Prefecture, Japan, is described and illustrated. In its trilobed column with a strongly incurved central lobe, this species shows a close affinity to G. flexistyla from Taiwan, but it is easily distinguished from G. flexistyla by several characteristics, including taller stature during the flowering period and completely cleistogamous flowers with a smaller and narrower perianth tube.
... The process of viscous secretions from stigmatic cavity is well known in orchids, and is finally responsible for successful capture of pollen from insect's back, therefore making pollination process accomplished. No movement of stigma/ anther/ pollinia/ perianth was observed during presently investigated pollination process in C. pendulum; such modifications together with over secretion of stigmatic fluid are generally associated with self pollinated orchid species (Liu et al. 2006). Frequency of pollination was observed to be very high in artificially pollinated flowers. ...
Article
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Mechanism and success of pollination is described in Cymbidium pendulum (Roxb.) Sw., a highly priced ornamental orchid enlisted in Appendix II of CITES. The species was found strictly entomophilous and workers of 2 honey bee species (Apis cerana, A. mellifera) acted as effective pollinating agents. Insects carry the pollen packets (pollinia) on their back and during random visits to different flowers, deposit the same to stigma. Allogamy was the most prevalent pollination mode and successful pollination was recorded in 8.49 percent flowers
... Delayed self-pollination (DSP) is considered to be a successful strategy to promote out-crossing in the early stages while assuring reproduction, especially when very limited reproductive success occurs in the early stages. DSP can be achieved through several mechanisms, which include bending of the stigma towards the anther (Zhang & Li 2008) or facilitation of pollen transfer to the stigma through anther movements (Liu et al. 2006;Shivanna 2012). The change of growth rates of stamen and pistil has been reported in other plants, and hypothesized before to contribute to self-pollination (Kalisz et al. 1999;Ma et al. 2012), as the spatial overlap of stigma and anther generally occurs while the stigma is still receptive, hence allowing for successful self-pollination. ...
Article
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Self-pollination has been hypothesized to be beneficial in environments where pollinators are rare as it can provide reproductive assurance. This study presents evidence for an autonomous self-fertilization mechanism in the winter flowering plant, Brandisia hancei. To determine changes in the spatial separation of stigma and anthers, the length of style and stamens was recorded. Additionally, pollination treatments were carried out to test fruit-set and seed production. Brandisia hancei is herkogamic in the early flowering stages. However, different growth rates of the filament and style lead to contact of stigma and anthers in the later stages, thereby facilitating self-pollination. The highest seeds number is produced under an out-crossing scenario but plants produce a considerable number of seeds even when purely selfed. Although pollinators are scarce, autonomous selfing alleviates the pollen limitation in B. hancei. Self-fertilization in B. hancei seems to be an adaptive strategy to ensure reproduction when pollinators are scarce.
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Societal Impact Statement Understanding plant reproductive strategies is vital for conserving endangered species. This study reveals a novel self‐pollination mechanism in the diminutive orchid Stigmatodactylus sikokianus, facilitated by the movement of a finger‐like appendage beneath the stigma. While this less‐than‐1‐mm‐long structure inspired the name Stigmatodactylus, its ecological function remained unknown for over 130 years—until now. The findings suggest that this appendage facilitates delayed self‐pollination, likely ensuring reproductive success under conditions of pollinator scarcity. Furthermore, the research highlights the value of integrating taxonomy with functional morphology to advance our understanding of pollination ecology. Summary Orchidaceae is one of the largest and most morphologically diverse plant families, largely due to intricate relationships with pollinators. However, autonomous self‐pollination is relatively common, likely as an adaptation to limited pollinator availability. This study examines the reproductive mechanism of the diminutive orchid Stigmatodactylus sikokianus, focusing on the finger‐like appendage beneath the stigma. The reproductive biology of S. sikokianus was investigated through pollination observations, artificial pollination experiments, and detailed studies of column morphology. Pollination experiments demonstrated that S. sikokianus primarily relies on autonomous self‐pollination, as indicated by high fruit set in bagged flowers and no fruit set in emasculated ones. Microscopic analysis revealed that the dactyliform appendage arcs toward the stigma, maintaining its straight structure, and eventually adheres to the stigma surface, allowing contact between the appendage apex and pollinia. UV microscopy showed thick bundles of pollen tubes penetrating the appendage adhered to the stigma and reaching the base of the column. The absence of pollen tube formation before contact between the appendage apex and pollinia suggests that autogamy occurs exclusively through the appendage at a later flowering stage. This study uncovers a novel self‐pollination mechanism in orchids, where the movement of the stigma appendage likely facilitates delayed selfing. This mechanism ensures seed production and likely reproductive success in S. sikokianus, enabling it to thrive in shaded environments with limited pollinator availability. The discovery highlights the value of integrating taxonomic and ecological approaches, as morphological traits provide valuable insights into species life histories.
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Canscora alata (Roth) Wall. (Gentianaceae) commonly known as Shankhapushpi, is an annual herbaceous threatened medicinal plant distributed mainly in the understory of wild Sal (Shorea robusta Gaertn.) forest and demands immediate conservation measures, for which understanding of its reproductive ecology is important. We studied aspects of floral biology, reproductive phenology and the breeding systems of the plant species. While undertaking the experiments, it was found that the species is self-compatible with a greater capability of autonomous self-pollination and doesn’t depend largely on pollinators for seed sets. However, geitonogamous and xenogamous modes of reproduction were observed. In natural habitat, visitors' frequency was extremely low, and most of the time they were absent. Outcrossing is rare, but it is occasionally facilitated by the fly, Paragus (Paragus) Latreille. We observed an "open-close-reopen" flowering rhythm during the anthesis of a flower. The mode of floral development clearly indicates that autonomous self-pollination is favored by the movement of stamens, styles, and stigmas during its “open-close-reopen” pattern of flowering. The plant also exhibits a larger anisomorphic stamen, orange in color. Even though the “fail safe” mechanism is an adaptive trait seen in outcrossing plant species, we have observed it here as well. The larger anisomorphic stamen helped to pollinate in order to ensure reproductive assurance through a delayed selfing mechanism; this is a rare occurrence in autogamous species. Despite self-compatibility, the ability to produce fruits and seeds through hand cross-pollination treatments implies that the plant species follow a selfing-outcrossing strategy to assure successful reproduction in its natural habitat. We hope these findings will be useful in strategic planning for the conservation of this plant species.
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Premise of the study: Male and female reproductive success is enhanced (increased outcrossing and seed production) by stamen movement in species which have few stamens per flower. Does such enhancement also occur in species which have many stamens per flower? Methods: We examined the effects of stamen movement on male and female reproductive success in Anemone flaccida, which has many stamens per flower. We measured stamen movement, including temporal changes in anther-stigma and anther-anther distances. We controlled stamen movement experimentally. Key results: The anthers moved horizontally away from the stigmas with increasing flower age, resulting in reduction in female-male interference. The dehisced anthers tended to move further away from the stigmas while the undehisced or dehiscing anthers remained nearer to them. The number of anthers touched per flower visit was higher in flowers whose stamens were fixed in the pre-movement position than in flowers whose stamens were fixed in the post-movement position or in flowers that were not manipulated. Thus, this position may promote male reproductive success. Seed production was lower for the untreated flowers than for the post-movement position flowers, suggesting that the post-movement stamen position is advantageous and stamen movement is suboptimal for female reproductive success. Conclusions: Stamen movement promotes male reproductive success in the early flowering stage and female reproductive success in the late flowering stage. In species having many stamens per flower, female-male interference can be reduced, but not eliminated, by stamen movement due to the conflict between female and male reproductive successes. This article is protected by copyright. All rights reserved.
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Dendrobium, one of the largest genera of tropical orchids, is grown commercially on a large scale with an important economic impact in several ASEAN countries. Dendrobium orchids can be grown in a wide range of climates, but flower production is best under tropical conditions. Due to being the most popular orchid for cut flower production, many hybrids of Dendrobium have been produced with colorful and attractive blooms. Cut flowers of Dendrobium are popular worldwide. In addition, many Dendrobium cultivars can be grown as flowering potted plants and for other purposes such as in medicinal applications and for use in decorative products. Postharvest physiology and technology are important in maintaining the quality of both cut flowers and potted plants from production sites to the marketplace. Plants of the Dendrobium genus also contain a wide diversity of bioactive compounds that can be developed into medicinal and cosmetic products. This review describes the botany, cultivation, postharvest physiology, handling and utilization of Dendrobium.
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Floral organ movements that ensure autonomous selfing are likely to occur in species that grow in habitats with pollinator scarcity and/or an unpredictable environment. Stamen curvature and temporal flower closure are two important floral behaviors that can influence plant pollination mode and reproductive success. However, both behaviors are rarely reported within a species, and little is known about how these two movements of floral organs ensure reproductive success in an unpredictable early spring environment with few pollinators. The aim of this study was to assess whether stamen curvature and temporal flower closure ensure successful reproduction of Leontice incerta in its cold desert habitat. Flowering phenology, floral traits, stamen curvature patterns and flower visitors were surveyed. The breeding system, capacity and timing for autonomous selfing were estimated by pollination manipulations. The timing of floral opening and closure, and benefits of temporal flower closure were determined. We found that flowering of L. incerta began in late March to early April in two populations in two years, and the yellow flowers had neither nectar nor scent. Floral visitation occurred very rarely, but bees (Colletes sp.) were potential pollinators. Fruit and seed set of open and bagged flowers did not differ significantly from that of self-pollinated or cross-pollinated flowers. However, removal of stamens significantly decreased seed set. Self-pollination occurs when the stamens curve and anthers touch the stigma autonomously, suggesting autonomous selfing assurance of seed production in this self-compatible species. Both fruit and seed set of flowers that were prevented from closing were significantly lower than those of control flowers and closed flowers treated with simulated rain treatment. Therefore, stamen curvature and temporal floral closure can ensure successful sexual reproduction of L. incerta in early spring in the cold desert, where lack of pollinators otherwise may lead to pollination failure.
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Rheum webbianum Royle is an important endemic medicinal plant species growing in Western Himalaya. The plant species has been categorized as vulnerable in this region. Keeping in view its medicinal importance and the threatened nature, the present study has been carried out to understand its breeding behavior which may prove helpful in the conservation and sustainable use of this important medicinal plant. The unique movement of stigmas avoids self-pollination in the species. In addition, protandry and high pollen/ovule ratio also favours cross pollination in the species. The species has adapted to the cross pollination in order to generate the genetic variability to withstand the harsh environmental conditions in alpines where the species grows. This genetic variability is maintained by vegetative reproduction through rhizomes.
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We investigate the two families of two-dimensional photonic crystal microlasers that are classified according to the approach used for the lateral confinement of the light (via trapping photons in a microcavity or via slowing down optical modes at an extreme of the dispersion characteristics), with a special emphasis on the characteristics of devices below and at laser threshold. The respective merits and drawbacks of the two families are analyzed in the light of an analytical modeling and of experimental results obtained on a variety of microlaser devices. The latter are processed in an InP-membrane heterostructure bounded onto silica on silicon. Promising prospects, which are expected from the combination of the two confinement approaches, are discussed.
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Surface-emitting diode lasers containing a second-order Bragg grating with a central phaseshift, Δϕ, of values around π are found to fundamentally favor lasing in a mode of symmetric near-field amplitude profile, which in turn provides emission in a single-lobed beam orthonormal to the surface. Devices of 500 μm long distributed-feedback (DFB) active region (λ = 0.98 μm) and 500 μm long distributed feedback reflector passive regions provide, for Δϕ = π, a surface-emitted beam pattern with 88% central-lobe power content, and external differential quantum efficiency, ηD, of 51%. Since the guided field is antisymmetric to start with, and a central π phaseshift causes two grating-outcoupled beams to be out-of-phase with each other, the net result is a single-lobed far-field pattern. The guided-field peak-to-valley (intensity) ratio, R, in the active (i.e., DFB) region is only 2, which insures single-mode operation to high powers, since the intermodal discrimination is high (⩾100 cm−1). Over a wide range in Δϕ:60°; ηD remains high (>50%) and the degree of guided-field uniformity remains low (R<2). © 2001 American Institute of Physics.
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Mixed mating, in which hermaphrodite plant species reproduce by both self-and cross-fertilization, presents a challenging problem for evolutionary biologists. Theory suggests that inbreeding depression, the main selective factor opposing the evo-lution of selfing, can be purged with self-fertilization, a process that is expected to yield pure strategies of either outcrossing or selfing. Here we present updated evidence sug-gesting that mixed mating systems are frequent in seed plants. We outline the floral and pollination mechanisms that can lead to intermediate outcrossing, review the theoreti-cal models that address the stability of intermediate outcrossing, and examine relevant empirical evidence. A comparative analysis of estimated inbreeding coefficients and outcrossing rates suggests that mixed mating often evolves despite strong inbreeding depression. The adaptive significance of mixed mating has yet to be fully explained for any species. Recent theoretical and empirical work suggests that future progress will come from a better integration of studies of floral mechanisms, genetics, and ecology, and recognition of how selective pressures vary in space and time.
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Differences in the frequency with which offspring are produced asexually, through self-fertilization and through sexual outcrossing, are a predominant influence on the genetic structure of plant populations. Selfers and asexuals have fewer genotypes within populations than outcrossers with similar allele frequencies, and more genetic diversity in selfers and asexuals is a result of differences among populations than in sexual outcrossers. As a result of reduced levels of diversity, selfers and asexuals may be less able to respond adaptively to changing environments, and because genotypes are not mixed across family lineages, their populations may accumulate deleterious mutations more rapidly. Such differences suggest that selfing and asexual lineages may be evolutionarily short-lived and could explain why they often seem to be of recent origin. Nonetheless, the origin and maintenance of different reproductive modes must be linked to individual-level properties of survival and reproduction. Sexual outcrossers suffer from a cost of outcrossing that arises because they do not contribute to selfed or asexual progeny, whereas selfers and asexuals may contribute to outcrossed progeny. Selfing and asexual reproduction also may allow reproduction when circumstances reduce opportunities for a union of gametes produced by different individuals, a phenomenon known as reproductive assurance. Both the cost of outcrossing and reproductive assurance lead to an over-representation of selfers and asexuals in newly formed progeny, and unless sexual outcrossers are more likely to survive and reproduce, they eventually will be displaced from populations in which a selfing or asexual variant arises.
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The transition from outcrossing to self-fertilization is one of the most common evolutionary trends in plants. Reproductive assurance, where self-fertilization ensures seed production when pollinators and/or potential mates are scarce, is the most long-standing and most widely accepted explanation for the evolution of selfing, but there have been few experimental tests of this hypothesis. Moreover, many apparently adaptive floral mechanisms that ensure the autonomous production of selfed seed might use ovules that would have otherwise been outcrossed. This seed discounting is costly if selfed offspring are less viable than their outcrossed counterparts, as often happens. The fertility benefit of reproductive assurance has never been examined in the light of seed discounting. Here we combine experimental measures of reproductive assurance with marker-gene estimates of self-fertilization, seed discounting and inbreeding depression to show that, during 2 years in 10 Ontario populations of Aquilegia canadensis (Ranunculaceae), reproductive assurance through self-fertilization increases seed production, but this benefit is greatly outweighed by severe seed discounting and inbreeding depression.
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Pollen grains from most flowering plants are transported by wind or animals and deposited on the receptive surface of the stigma of a different individual, but self-pollination is also common. We have discovered a new process for self-pollination in the laterally orientated flowers of a Chinese herb, in which a film of pollen is transported from the anther (pollen sacs) by an oily emulsion that slides sideways along the flower's style and into the individual's own stigma. This mode of self-pollination is a new addition to the broad range of genetic and morphological mechanisms that have evolved in flowering plants (angiosperms), and may be common in species growing in shady, windless and insect-poor habitats.
Article
The evolution of inbreeding in plants has often been attributed to selection for the ability to set seed in the absence of mates or pollinators. Mechanisms of reproductive assurance in five populations of mixed mating Mimulus guttatus, three populations of inbreeding M. platycalyx, and two populations of inbreeding M. nasutus were examined in a pollinator-free greenhouse. Reproductive assurance was manifested in all populations by autofertility, vegetative reproduction, or both. The inbreeding taxa had significantly greater levels of autofertility and less vegetative reproduction. Three modes of autofertility were identified: 1) due to corolla abscission only, occurring in three M. guttatus populations; 2) due to both corolla abscission and direct anther-stigma contact by curling of the lower stigmatic lobe into the anthers, occurring in two M. guttatus populations; and 3) direct stigma-anther contact by stigma curling alone prior to corolla abscission, found in each M. platycalyx and M. nasutus population. Stigma-anther distance and its interaction with stigma curling contributed to differences in autofertility among populations. Significant levels of intrapopulation quantitative genetic variation were found for seven of ten traits examined; average levels were similar between inbreeding and mixed mating populations. Genetic variation within populations for autofertility per se was not detected, but significant levels controlling stigma-anther distance were found in two M. guttatus populations. These results show that evolution of inbreeding by natural selection for reproductive assurance is possible in Mimulus, and illustrate the complex changes in floral dynamics and morphology it may involve.
Article
The evolution of inbreeding in plants has often been attributed to selection for the ability to set seed in the absence of mates or pollinators. Mechanisms of reproductive assurance in five populations of mixed mating Mimulus guttatus, three populations of inbreeding M. platycalyx, and two populations of inbreeding M. nasutus were examined in a pollinator-free greenhouse. Reproductive assurance was manifested in all populations by autofertility, vegetative reproduction, or both. The inbreeding taxa had significantly greater levels of autofertility and less vegetative reproduction. Three modes of autofertility were identified: 1) due to corolla abscission only, occurring in three M. guttatus populations; 2) due to both corolla abscission and direct anther-stigma contact by curling of the lower stigmatic lobe into the anthers, occurring in two M. guttatus populations; and 3) direct stigma-anther contact by stigma curling alone prior to corolla abscission, found in each M. platycalyx and M. nasutus population. Stigma-anther distance and its interaction with stigma curling contributed to differences in autofertility among populations. Significant levels of intrapopulation quantitative genetic variation were found for seven of ten traits examined; average levels were similar between inbreeding and mixed mating populations. Genetic variation within populations for autofertility per se was not detected, but significant levels controlling stigma-anther distance were found in two M. guttatus populations. These results show that evolution of inbreeding by natural selection for reproductive assurance is possible in Mimulus, and illustrate the complex changes in floral dynamics and morphology it may involve.
Article
There has been extensive theoretical study of the evolution of self-fertilization in hermaphroditic or monoecious flowering plants because self-compatible species with high rates of self-fertilization are often derived from outcrossing ancestors1–4. Such studies have shown that a gene causing an increased rate of self-fertilization has an advantage because the mother transmits genes via both pollen and egg to selfed progeny5, and thereby evades the ‘cost of meiosis’6–8. Selfing also may be advantageous if the amount of pollen available to fertilize ovules by outcrossing is limited1,2,4,6. However, these advantages are offset, at least partially, if the fitness of selfed progeny is lower than that of outcrossed progeny, due to inbreeding depression1,2,6,7,9,10. Biogeographical evidence suggests that reduced pollinator activity may be sufficient to counteract this disadvantage and permit the evolution of selfing in populations in ecologically marginal areas1–4, but direct evidence is usually lacking. Here we show that the self-fertile homostyle variant of the primrose Primula vulgaris, which reaches high frequencies in certain populations11, experiences a fertility advantage, in terms of seeds per plant, as a result of its high rate of self-fertilization.
Article
Cleistogamy-the production of open (chasmogamous-CH) and closed (cleistogamous-CL) floral forms by a species-is widespread among the angiosperms. While the CL flower is autogamous, the CH flower may provide a means for outcrossing. The term "cleistogamy" has also been used to describe other phenomena. A classification of types of cleistogamy is proposed. In this review, a restricted definition of cleistogamy is used to refer to species which show real floral dimorphisms, with divergent developmental pathways leading to CL and CH as well as intermediate floral forms. Reductions in the androecium and corolla are the most common feature of the CL flowers. The structural, developmental, and functional aspects of cleistogamy are reviewed. Evidence is presented to show that the CL flowers have modifications in their development which ensure self pollination. A proposal is made for using this phenomenon of dimorphic flower production as a system for the study of floral morphogenesis, function and evolution.
Article
Lasing action of a surface-emitting laser with a two-dimensional photonic crystal structure is investigated. The photonic crystal has a triangular-lattice structure composed of InP and air holes, which is integrated with an InGaAsP/InP multiple-quantum-well active layer by a wafer fusion technique. Uniform two-dimensional lasing oscillation based on the coupling of light propagating in six equivalent Γ - X directions is successfully observed, where the wavelength of the active layer is designed to match the folded (second-order) Γ point of the Γ - X direction. The very narrow divergence angle of far field pattern and/or the lasing spectrum, which is considered to reflect the two-dimensional stop band, also indicate that the lasing oscillation occurs coherently. .
Article
Charles Darwin recognized that flowering plants have an unrivalled diversity of sexual systems. Determining the ecological and genetic factors that govern sexual diversification in plants is today a central problem in evolutionary biology. The integration of phylogenetic, ecological and population-genetic studies have provided new insights into the selective mechanisms that are responsible for major evolutionary transitions between reproductive modes.
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