Bulked Segregant RNA-Seq Analysis of Pollinated Pistils Reveals Genes Influencing Spikelet Fertility in Rice

Prezygotic isolation is important for successful fertilization in rice, significantly affecting yield. This study focused on F_(5:6) generation plants derived from inter-subspecific crosses(Nipponbare × KDML105) with low(LS) and high seed-setting rates(HS), in which normal pollen fertility was observed. However, LS plants showed a reduced number of pollen grains adhering to the stigma and fewer pollen tubes reaching the ovules at 4-5 h post-pollination, compared with HS plants. Bulked segregant RNA-Seq analysis of pollinated pistils from the HS and LS groups revealed 249 and 473 differentially expressed genes(DEGs), respectively. Kyoto Encyclopedia of Genes and Genomes analysis of the HS and LS-specific DEGs indicated enrichment in metabolic pathways, pentose and glucuronate interconversions, and flavonoid biosynthesis. Several of these DEGs exhibited co-expression with pollen development genes and formed extensive clusters of co-expression networks. Compared with LS pistils, enzyme genes controlling pectin degradation, such as OsPME35 and OsPLL9, showed similar expression patterns, with higher levels in HS pistils pre-pollination. Os02g0467600, similar to cinnamate 4-hydroxylase gene(CYP73), involved in flavonoid biosynthesis, displayed higher expression in HS pistils post-pollination. Our findings suggest that OsPME35, OsPLL9, and Os02g0467600 contribute to prezygotic isolation by potentially modifying the stigma cell wall(OsPME35 and OsPLL9) and controlling later processes such as pollen-stigma adhesion(Os02g0467600) genes. Furthermore, several DEGs specific to HS and LS were co-localized with QTLs and functional genes associated with spikelet fertility. These findings provide valuable insights for further research on rice spikelet fertility, ultimately contributing to the development of high-yielding rice varieties.

A Comparative Study on the Quality Components Between Self Pollinated Seeds and Naturally Pollinated Seeds in Brassica napus L. in Sichuan Ecological Region

[ Objective] This study was to reveal the differences in crude fat and glucosinolates between self pollinated seeds and naturally pollinated seeds in Brassica napus in sichuan ecological region.. [ Method] Near-infrared spectroscopy method （NIRS） was employed to measure the quality components in self pollinated seeds and naturally pollinated seeds of 861 shares of Brassica napus from Sichuan ecological region. And correlation analysis and regression analysis were conducted based on the experimental data via SPSS （statistics package for social science）. [ Result] The contents of crude fat in the self pollinated seeds were commonly a higher than that in the naturally pollinated seeds at 0.01 significant level; while the contents of glucosinolates in the self pollinated seeds and the naturally pollinated seeds were insignificantly different. Both the correlation relationship and linear regression for the crude fat between the self pollinated seeds and naturally pollinated seeds reached the significant level. The regression equations for the contents of crude fat（y1 ） and glucosinolates（ y2 ） in the naturally pollinated seeds and of crude fat（ x1 ） and glucosinolates（ x2 ） in self pollinated seeds were respectively determined to be y1 = 16.844 ＋0.614x1 and y2 = -0.620 ＋ 1.017 x2. [ Conclusion] In Brassica napus breeding, crude fat in naturally pollinated seeds should be emphatically taken into account, meanwhile concurrently considering that in self pollinated seeds; while glucosinolates in both the self pollinated seeds and the naturally pollinated seeds must be simultaneously concerned.

Geographic Variation in Flower Size and Flower-Visitor Composition of Two Bumblebee-Pollinated, Spring-Flowering Herbs, <i>Lamium album</i>L. var. <i>barbatum</i>(Lamiaceae) and <i>Meehania urticifolia</i>(Lamiaceae)

Geographic variation of flower size is potentially affected by various biotic and abiotic factors such as pollinator size, abundance of nectar robbers, and temperature. To elucidate the effect of geographic variation of flower-visitor fauna on flower size, we investigated two spring-flowering, bumblebee-pollinated herbs, Lamium album L. var. barbatum (seven populations) and Meehania urticifolia (five populations), in central Japan. Flower-size variations were not correlated with altitude (an index of abiotic environmental change) in either species, but in both species they were related to the local species composition of flower visitors. In L. album, flowers were bigger in populations visited by long-tongued Bombus consobrinus and B. diversus queens, whereas they were smaller in populations visited by short-tongued bees such as Apis mellifera. Flower size did not vary much among populations of M. urticifolia visited by long-tongued bumblebees, but it was uniquely small in a population whose flowers were predominantly visited by the nectar-robbing bee Megachile japonica. In conclusion, both the size and nectar-robbing behavior of bees affect local flower-size adaptation in these two long-tubed, spring-flowering herbs.

Variation analyses of controlled pollinated families and parental combining ability of Pinus koraiensis

To evaluate and select elite Pinus koraiensis parent combinations and offspring families,34 full-sib families were evaluated.Variance analysis of tree height,diameter at breast height and volume showed no significant differences among each block,the interaction of block,male and female.The family heritability of all traits were high(>0.9).Phenotypic and genotypic coefficients of variance of height,diameter at breast height,and volume showed that the phenotypic coefficient of variation of volume in the same combination was higher than height and diameter at breast height,indicating that volume was the main factor determining excellent single plant selection.The female and male trees with the best general combining ability indicated that the optimal parental hybridization was not necessarily the optimal combination.In addition,the least parents of hybrid offspring performance were always relatively poor and should not be selected as hybrid parents.Additionally,we found there was no significant difference among the effects of female and male parents by random modelling,but there were significant differences by fixed modelling.The most significant effect of female-and male interaction,and the selection of better female or male parents in the test parent group should be efficient as well as the results of significant variation among them by fixed modelling.For the evaluated breeding population of P.koraiensis,the backward selection of excellent parent combinations or forward selection of excellent individuals as progeny should be the major breeding strategies.

The only purple-flower species in Actaea L.is pollinated by a hornet

Examining the pollination biology of plant species is not only crucial for enhancing our understanding of their reproductive biology,but also essential for elucidating their adaptation and evolutionary history.Here,we investigated the breeding system and pollination biology of two closely related species in Actaea.The flower of A.purpurea is unique in the genus with purple and chartaceous(paper-like)sepals,fewer stamens with yellow anthers and purple filaments.Through three seasons of field observation and exclusion experiments,we determined that A.purpurea was primarily pollinated by a hornet species,Vespa bicolor,which also served as the most efficient pollinator.In contrast,A.japonica was primarily pollinated by large flies.Actaea purpurea exhibited a significantly higher cumulative nectar volume than A.japonica,which could be a crucial factor in attracting V.bicolor.A control experiment further demonstrated that removing the nectar leaf(petal)significantly decreased the visiting frequency of V.bicolor.Breeding system studies revealed that both species were self-compatible,yet they primarily underwent outcrossing in natural habitats.Our study presents a compelling case of possible pollinator shift in A.purpurea accompanied by morphological divergence.A more in-depth investigation of this system would offer crucial insights into the extent to which pollinators are involved in the plant speciation process and whether they contribute to reproductive isolation between closely related species.

Honeybees prefer novel insect-pollinated flower shapes over bird-pollinated flower shapes

Plant-pollinator in teractio ns have a fundame ntal in fluence on flower evolution. Flower color signals are frequently tuned to the visual capabilities of important pollinators such as either bees or birds, but far less is known about whether flower shape in fluences the choices of pollinators. We tested European honeybee Apis mellifera pref ere nces using novel achromatic (gray-scale) images of 12 insect-pollinated and 12 bird-pollinated native Australian flowers in Germany;thus, avoiding in flue nces of color, odor, or prior experie nee. In depende nt bees were tested with a number of parameterized images specifically desig ned to assess pref ere nces for size, shape, brightness, or the number of flower-like shapes prese nt in an image. We show that honeybees have a pref ere nee for visiti ng images of in sect-polli nated flowers and such a pref ere nee is most-likely mediated by holistic in formati on rather than by in dividual image parameters. Our results in dicate an giosperms have evolved flower shapes which in fluence the choice behavior of importa nt pollinators, and thus suggest spatial achromatic flower properties are an important part of visual signaling for plantpollinator in teractions.

Patterns and drivers of plant sexual systems in the dry-hot valley region of southwestern China

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.

Enhanced and asymmetric signatures of hybridization at climatic margins: Evidence from closely related dioecious fig species

Hybridization plays a significant role in biological evolution. However, it is not clear whether ecological contingency differentially influences likelihood of hybridization, particularly at ecological margins where parental species may exhibit reduced fitnesses. Moreover, it is unknown whether future ecosystem change will increase the prevalence of hybridization. Ficus heterostyla and F. squamosa are closely related species co-distributed from southern Thailand to southwest China where hybridization, yielding viable seeds, has been documented. As a robust test of ecological factors driving hybridization, we investigated spatial hybridization signatures based on nuclear microsatellites from extensive population sampling across a widespread contact range. Both species showed high population differentiation and strong patterns of isolation by distance. Admixture estimates exposed asymmetric interspecific gene flow.Signatures of hybridization increase significantly towards higher latitude zones, peaking at the northern climatic margins. Geographic variation in reproductive phenology combined with ecologically challenging marginal habitats may promote this phenomenon. Our work is a first systematic evaluation of such patterns in a comprehensive, latitudinally-based clinal context, and indicates that tendency to hybridize appears strongly influenced by environmental conditions. Moreover, that future climate change scenarios will likely alter and possibly augment cases of hybridization at ecosystem scales.

Intraspecific floral colour variation in three Pedicularis species

Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging,reducing reproductive interference in natural communities.The extent of flower constancy is largely determined by the floral traits of co-flowering species.Both higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower constancy.However,previous studies mainly focused on interspecific difference,and the intraspecific variation(consistency)of floral traits received much less attention.We hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering congeners.We investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19communities composed of either single or multiple Pedicularis species.Colour was quantified using image-based colour analysis as perceived by pollinators.We found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees,implying strongly constrained by the visual selection by pollinators.Contrary to the hypothesis,there is no significant difference in intraspecific floral colour variation between different community contexts.It may be due to the relatively large interspecific floral colour differences of most co-flowering species.The influence of community context on intraspecific variation may be reflected in floral traits other than colours.

Maximizing Resource Efficiency in Cloud Data Centers through Knowledge-Based Flower Pollination Algorithm (KB-FPA)

Cloud computing is a dynamic and rapidly evolving field,where the demand for resources fluctuates continuously.This paper delves into the imperative need for adaptability in the allocation of resources to applications and services within cloud computing environments.The motivation stems from the pressing issue of accommodating fluctuating levels of user demand efficiently.By adhering to the proposed resource allocation method,we aim to achieve a substantial reduction in energy consumption.This reduction hinges on the precise and efficient allocation of resources to the tasks that require those most,aligning with the broader goal of sustainable and eco-friendly cloud computing systems.To enhance the resource allocation process,we introduce a novel knowledge-based optimization algorithm.In this study,we rigorously evaluate its efficacy by comparing it to existing algorithms,including the Flower Pollination Algorithm(FPA),Spark Lion Whale Optimization(SLWO),and Firefly Algo-rithm.Our findings reveal that our proposed algorithm,Knowledge Based Flower Pollination Algorithm(KB-FPA),consistently outperforms these conventional methods in both resource allocation efficiency and energy consumption reduction.This paper underscores the profound significance of resource allocation in the realm of cloud computing.By addressing the critical issue of adaptability and energy efficiency,it lays the groundwork for a more sustainable future in cloud computing systems.Our contribution to the field lies in the introduction of a new resource allocation strategy,offering the potential for significantly improved efficiency and sustainability within cloud computing infrastructures.

Effect of Apis mellifera on community composition of local pollinator bees and their pollination network in Qinling Mountains and surrounding areas

The Qinling Mountains, known for their rich vegetation and diverse pollinating insects, have seen a significant decline in bee species richness and abundance over recent decades, largely due to the introduction and spread of Apis mellifera. This decline has caused cascading effects on the region's community structure and ecosystem stability. To improve the protection of native bees in the natural and agricultural landscape of the Qinling Mountains and its surrounding areas, we investigated 33 sampling sites within three habitats: forest, forest-agriculture ecotones, and farmland. Using a generalized linear mixing model, t-test, and other data analysis methods, we explored the impact of Apis mellifera on local pollinator bee richness, abundance, and the pollination network in different habitats in these regional areas. The results show that(1)Apis mellifera significantly negatively affects the abundance and richness of wild pollinator bees,while Apis cerana abundance is also affected by beekeeping conditions.(2)There are significant negative effects of Apis mellifera on the community structure of pollinator bees in the Qinling Mountains and its surrounding areas: the Shannon-Wiener diversity index, Pielou evenness index, and Margalef richness index of bee communities at sites with Apis mellifera influence were significantly lower than those at sites without Apis mellifera influence.(3)The underlying driver of this effect is the monopolization of flowering resources by Apis mellifera. This species tends to visit flowering plants with large nectar sources, which constitute a significant portion of the local plant community. By maintaining a dominant role in the bee-plant pollination network, Apis mellifera competitively displaces native pollinator bees, reducing their access to floral resources. This ultimately leads to a reduction in local bee-plant interactions, decreasing the complexity and stability of the pollination network. These findings highlight the need for targeted conservation efforts to protect native pollinator species and maintain the ecological balance in the Qinling Mountains.

Twenty-Three Years of Insect Pollinator-Dependent Crop Studies in Agro-Ecological Zones of Cameroon (2011-2020)

Cultivation of pollinator-dependent crops has expanded globally, increasing our reliance on insect pollination. This essential ecosystem service is provided by a wide range of managed and wild pollinators whose abundance and diversity are thought to be in decline, threatening sustainable food production. In Cameroon, several studies on pollinator-dependent crops carried out in different agro-ecological zones (AEZ) have been published in national and international journals, in order to present the importance and impact of flowering insects on fruit and seed yields of plant species. We proposed to produce a review article highlighting the different flowering insects and their importance for different plants according to AEZ, without however focusing on the quality of the journal (predator or non-predator) and how the different insects were identified (scientific names given in the publications). Thus, from 1997 to 2020, we collected 116 published papers from which only 26 were kept for this review. The results show that Hymenoptera, including the Apidae, followed by Megachilidae, are the most excellent pollinators of plant species in Cameroon, and they are present in different agro-ecological zones. The majority of publications focused on bees, particularly the honeybee Apis mellifera.

The ultraviolet colour component enhances the attractiveness of red flowers of a bee-pollinated plant

Aims Bee-pollinated flowers are rarely red,presumably because bees(which lack red receptors)have difficulty detecting red targets.Although the response of bees to red colour has been investigated in lab experiments,most stimuli have been pure red,while the subtle diversity of red as perceived by humans(human-red)has received very limited attention.Here we test the hypothesis that ultraviolet(UV)reflected from human-red flowers enhances their attractiveness to bees,through increased chromatic contrast.Methods Using Onosma confertum(Boraginaceae),a plant with UV-reflecting red flowers that are pollinated by bumblebees,we investigated the effects of UV reflection on pollinator responses by conducting phenotypic manipulation experiments in the field.Colour preferences of flower-naïve bumblebees were also examined.Colour perception by bumblebees was estimated in terms of chromatic and achromatic contrast,based on two different colour perception models.Important Findings We found that both natural and flower-naïve bumblebees strongly preferred visiting UV-reflecting targets compared with UV-absorbing ones.Colour models show that the UV-reflecting flowers exhibit higher spectral purity and higher chromatic contrast against the foliage background,whereas they have similar achromatic contrast in terms of green receptor contrast.These results indicate that the component of UV reflection increases chromatic contrast in O.confertum,enhancing the visual attractiveness of these red flowers to bumblebees.We further infer that the secondary reflectance might be a necessary component in human-red flowers that are primarily pollinated by animals without red receptors,such as bees.

Mast fruiting in a hawkmoth- pollinated orchid Habenaria glaucifolia: an 8-year survey

Aims The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants.it considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual.orchids produce huge numbers of seeds per fruit and rarely experience seed predation.it remains unclear which factors may affect fluctuating fruit production in orchids,which generally suffer a widespread pol-len limitation.To explore the temporal pattern of fruiting and poten-tial factors related to fluctuation in fruit production,we investigated reproductive success of a long-spurred orchid(Habenaria glaucifo-lia)in an alpine meadow with thousands of individuals over 8 years.Methods To estimate reproductive success,pollinator observation was con-ducted by day and at night,and pollinia removal and receipt were recorded in the field population for 8 years.To examine whether fruit set and seed set are pollen limited,we conducted supple-mentary pollination experiments and compared fruit set,seed set and pollinia movement of open-pollinated flowers from 2011 to 2013.We measured lengths of spurs and pollinator probos-cises,and nectar volume and concentration,to identify potential pollinators.Important Findings Hawkmoths were seen to be effective pollinators for H.glauci-folia in 3 years,whereas in the remaining 5 years no pollinators were observed,and consequently pollinia were rarely transferred.Numerous pollinia movements were observed in 2012,2013 and 2014(pollinia removal:48,59 and 85%;pollinia receipt 51,70 and 80%),and correspondingly fruit set was significantly higher in 2012 and 2013(59 and 46%)than in 2011(25%).it was fruit set,rather than seed set,that was pollen limited in this orchid in the 3 years,in that supplementary pollination increased fruit set but did not increase seed set per fruit compared to natural.Three species of hawkmoths had proboscis lengths that matched the spur length of H.glaucifolia.Fruit set in this long spurred orchid depends on the activity of long-tongued hawkmoths,resulting in significant tempo-ral variation in fruit production.mast fruiting in this alpine orchid could be attributed to a‘sit and wait’strategy,awaiting an abun-dance of effective pollinators.

Potential Autonomous Selfing in Gesneria citrina (Gesneriaceae),a Specialized Hummingbird Pollinated Species with Variable Expression of Herkogamy

Species with mixed mating systems often demonstrate variable expression of breeding system characteristics and thus represent the opportunity to understand the factors and mechanisms that promote both outcrossed and selfed seed production. Here, we investigate variation in levels of herkogamy （variation in stigma-anther separation distance） in a Puerto Rican population of hummingbird pollinated Gesneria citrina Urban. There is significant variation in herkogamy levels among individuals of this species and stigma-anther separation is negatively associated with the ability to set fruits and seeds in the absence of pollinators. The variation in levels of herkogamy may represent a mechanism to ensure the production of some self-fertilized progeny in the absence of hummingbird pollinators. We also describe a novel breeding system in G. citrina, where stamens elongate over time to reach stigma height, but stamen elongation is accelerated by pollination. These results suggest that once the flowers are pollinated, stamen elongation may favor increased pollen removal and siring success, while the reduction in stigma-anther distance no longer imposes the risk of interference between male and female functions. We discuss our findings of breeding system variation in the context of pollination system evolution in an island setting （Antillean islands）.

Defining honeybee subspecies in an evolutionary context warrants strategized conservation

Despite the urgent need for conservation consideration,strategic action plans for the preservation of the Asian honeybee,Apis cerana Fabricius,1793,remain lacking.Both the convergent and divergent adaptations of this widespread insect have led to confusing phenotypical traits and inconsistent infraspecific taxonomy.Unclear subspecies boundaries pose a significant challenge to honeybee conservation efforts,as it is difficult to effectively prioritize conservation targets without a clear understanding of subspecies identities.Here,we investigated genome variations in 362 worker bees representing almost all populations of mainland A.cerana to understand how evolution has shaped its population structure.Whole-genome single nucleotide polymorphisms(SNPs)based on nuclear sequences revealed eight putative subspecies,with all seven peripheral subspecies exhibiting mutually exclusive monophyly and distinct genetic divergence from the widespread central subspecies.Our results demonstrated that most classic morphological traits,including body size,were related to the climatic variables of the local habitats and did not reflect the true evolutionary history of the organism.Thus,such morphological traits were not suitable for subspecific delineation.Conversely,wing vein characters showed relative independence to the environment and supported the subspecies boundaries inferred from nuclear genomes.Mitochondrial phylogeny further indicated that the present subspecies structure was a result of multiple waves of population divergence from a common ancestor.Based on our findings,we propose that criteria for subspecies delineation should be based on evolutionary independence,trait distinction,and geographic isolation.We formally defined and described eight subspecies of mainland A.cerana.Elucidation of the evolutionary history and subspecies boundaries enables a customized conservation strategy for both widespread and endemic honeybee conservation units,guiding colony introduction and breeding.

Does pollinator dependence decrease along elevational gradients?

Plants have long been thought to be less dependent on pollinators for seed production at higher elevations due to adverse pollination environments.However,recent research has yet to consistently support the generality of this expectation.In this study,we asked whether pollinator dependence decreases along an elevational gradient and how it varies with various reproductive traits.To answer these questions,we quantified pollinator-plant associations and various reproductive traits for 112 flowering plants spanning a large elevational gradient(990-4260 m a.s.l.)in the Qinghai-Tibet Plateau.We found that flowering plants in the Qinghai-Tibet Plateau region are highly dependent on pollinators for seed production(76.2%of seed production was contributed by animal pollinators and 44.6%of plants would produce no seed without pollinator visitation).Contrary to our expectation,there was no significant elevational gradient in pollinator dependence index.Although the pollinator dependence index was not significantly correlated with pollen limitation,flower size,floral longevity,or reward type,it was correlated with compatibility status and flowering time.These findings indicate that pollinator dependence does not decrease along an elevational gradient in the Qinghai-Tibet Plateau.Our study also highlights the severe vulnerability of flowering plant seed production to pollinator declines under global change in the Qinghai-Tibet Plateau region,particularly for early-flowering or self-incompatible plants growing at higher elevations(e.g.,subnival belt).

Floral trait variation across individual plants within a population enhances defense capability to nectar robbing

Floral trait variation may help pollinators and nectar robbers identify their target plants and,thus,lead to differential selection pressure for defense capability against floral antagonists.However,the effect of floral trait variation among individuals within a population on multi-dimensional plant-animal interactions has been little explored.We investigated floral trait variation,pollination,and nectar robbing among individual plants in a population of the bumble bee-pollinated plant,Caryopteris divaricata,from which flowers are also robbed by bumble bees with varying intensity across individuals.We measured the variation in corolla tube length,nectar volume and sugar concentration among individual plants,and evaluated whether the variation were recognized by pollinators and robbers.We investigated the in-fluence of nectar robbing on legitimate visitation and seed production per fruit.We found that the primary nectar robber(Bombus nobilis)preferred to forage on plants with long-tubed flowers,which produced less nectar and had lower sugar concentration compared to those with shorter corolla tubes.Individuals with shorter corolla tubes had comparatively lower nectar robbing intensity but higher visitation by legitimate visitors(mainly B.picipes)and higher seed production.Nectar robbing signifi-cantly reduced seed production because it decreased pollinator visits.However,neither pollination nor seed production differed between plants with long and short corolla tubes when nectar robbers were excluded.This finding suggests that floral trait variation might not be driven by pollinators.Such variation among individual plants thus allows legitimate visitors and nectar robbers to segregate niches and enhances population defense against nectar robbing in unpredictable conditions.

Degree of style coiling is associated with corolla-tube length in the nectarless flowers of Roscoea schneideriana

The plant-pollinator‘arms race’model posits that a major driver of the evolution of elongated corollas in flowers is reciprocal selection for‘morphological fit’between pollinator-tongue length and access distance to nectar(usually corolla-tube length).Evidence for the pollinator-mediated selection on tube length and evolution of multiple,correlated floral traits remains inconclusive.To gain possible insights into the strength of stabilizing selection by assessing standing phenotypic variation,we measured a series of functionally important floral traits,including corolla tube length and‘effective’tube depth and degree of style coiling.We then calculated coefficients of variation(CV)for these traits in three field populations of R.schneideriana.Unlike in most long-tubed flowers,the bottom part of the corolla tube is completely occupied by the style,with no room for nectar.The length of this portion of the corolla tube was more variable(higher CV)than the upper part of the corolla tube,suggesting that functional tube depth was under stronger stabilizing selection.The degree of style coiling was negatively related to the corolla-tube length in all three populations of R.schneideriana,suggesting that there may be conflicting selection acting on style length and corolla-tube length,which are otherwise usually tightly correlated.Given the lack of nectar in the flowers of this species,the long corolla tubes and long styles may represent morphological holdovers from ancestors that were pollinated by long-tongued pollinators,as is still seen in related species in the western Himalayas.

Pollination Biology of the Endangered Herbal Medicines Dendrobium chrysotoxum(Orchidaceae)

Pollination biology studies of the endangered herbal medicines Dendrobium chrysotoxum were conducted in natural pollination conditions using flower observation,pollinator observation and artificial pollination experiments.Populations of D.chrysotoxum with fragrance and nectar were pollinated by Ctenoplectra davidi Valhalla(Hymenoptera:Apidae)species.The floral structure of D.chrysotoxum adapted precisely to its pollinators.Flowers had a low capsule setting(0.17%)under natural conditions.However,compared to open pollination,artificial pollination experiments showed a significant increase in capsule setting,and D.chrysotoxum was cross-compatible and self-compatible,but there was pollinator limitation also.This study will provide important information for the preservation of this endangered species.