草果两型植株的繁育差异研究

草果(Amomum tsaoko)是具有柱头卷曲机制的姜科植物,该研究通过观察和分析传粉者的访花行为、草果的花蜜分泌和最终的结实率,探索其花蜜分泌模式与传粉行为的相互关系,以及对其两型植株繁殖的影响。结果表明:草果两型植株的花蜜分泌在1 d花期的16:40—19:00期间达到高峰;上举型花比下垂型花能够提供更多的花蜜,下垂型花的花蜜分泌受环境温度、光照、湿度的显著影响,其结实率也显著低于上举型花。中华蜜蜂(Apis cerean cerana)是观察点频率最高的有效传粉者,在1 d花期里访花频率呈现双峰模式,访花行为受到温度和湿度的显著影响,78%或18℃较适宜访花。1 d花期中温度、湿度的变化,以及花蜜的动态分泌模式共同促进这一双峰访花模式的形成。草果花蜜分泌模式和双峰访花模式均与草果的柱头卷曲运动匹配,对吸引昆虫精确传粉、维持柱头卷曲机制有重要意义。草果两型植株之间,环境因素对它们花蜜分泌的影响显著不同,导致传粉者不同的访花行为反应和繁殖结果。适当增加居群中上举型植株数量,可能是提高产量的一个有效方法。     

草豆蔻传粉生物学的研究

比较研究了花柱卷曲性植物草豆蔻 Alpinia hainanensis两种表型(上举型和下垂型)的传粉生物学特性。结果表明:草豆蔻的花柱卷曲运动节律与其他已报道的山姜属Alpinia植物基本一致,而下垂型花的花柱卷曲运动明显滞后于上举型花约2 h。草豆蔻的花柱卷曲运动中存在一些不同步的现象,甚至在同一花序上的两朵花的花柱运动节律亦会表现出不一致的现象,但上举型花的花药开裂时间却严格同步,都发生在同类型个体的柱头全部位于花药上方之后进行。草豆蔻上举型花的花蜜分泌量、单花花粉量、花粉/胚珠比率(P/O)均明显比下垂型花多,而两种表型的胚珠数、花蜜糖含量、氨基酸含量无显著差异。在草豆蔻的单花期内不同时间段进行人工授粉,上举型花在其柱头位于花药下方时进行人工授粉,其结实率明显比柱头位于花药上方时人工授粉的处理高,下垂型花则没有显著差异。在自然居群中,草豆蔻的主要传粉者是无垫蜂Ameglla sp.和两种木蜂Xylocopa sp.,但存在传粉者不足而影响结实率的现象。完全套袋、去雄和去雌(去柱头)处理的均不结实,表明草豆蔻中不存在无融合生殖、主动自花授粉和滞后自交的生殖保障现象。而人工自交和异交均具有较高的结实率,表明草豆蔻为自交亲和植物。草豆蔻的繁育系统是具花柱卷曲性运动的异花授粉的交配系统。     

益智传粉生物学的研究

 益智（Alpinia oxyphylla）的花期从2月底至4月下旬;单株花期（花序）约为16～26 d,通常为23～26 d;单花花期一般为1 d。正常情况下,益智和其它山姜属植物一样,具有花柱卷曲性促进异花授粉的机制,表现出两种类型：花柱上举型和花柱下垂型,其花柱卷曲运动的节律与其它已报道的山姜属植物基本一致。但观察发现,当遭遇低温天气时(日最高气温<18℃),单花花期延长为2 d,无论是上举型个体还是下垂型个体,均只表现出一种花型——下垂型：上午开花时花柱弯向上,柱头位于已开裂散发出花粉的花药上方,直到第二天上午6∶30～11∶00间,花柱才陆续地慢慢向下运动,柱头下降至与花药等高或位于花药下方。益智的主要传粉昆虫是蜜蜂（Apidae sp.）、木蜂（Xylocopa sp.）,绝大多数的访花者的访花目的是吸蜜。益智的花蜜分泌量（8.37～15.79 μl）和花蜜含糖量（30.12%～32.83%）较高,花蜜是益智作为传粉者访花的最主要的报酬。实验结果还表明,益智花部中唇瓣对昆虫访花有显著的招引作用;益智的花蜜对蜜蜂的访花频率有显著的影响,对木蜂有一定的招引作用,但并不显著。而花粉（花药）则对昆虫的访花频率影响不大。人工授粉实验结果表明益智存在自交亲和性,无论是上举型或下垂型个体自交和异交均有较高的结实率;人工自交和异交的结实率在上举型植株中存在较大的差异,而在下垂型个体中则差异不明显;去雄套袋、去柱头套袋和完全套袋不授粉等处理均不结实,表明益智不存在无融合生殖现象和自动自花授粉现象。益智的繁育系统是异花授粉交配系统。     

两种姜科花柱卷曲性植物柱头的位置与其可授性的关系

花柱卷曲性是一种见于姜科山姜属(Alpinia)和砂仁属(Amomum)植物中的独特的性二态现象, 具有这一性系统的植物, 其居群包括上举型和下垂型两种表型, 所有个体的雌雄性别功能在时间和空间上分离。本研究通过操控授粉和花粉管生长两项实验, 探讨花柱卷曲性植物个体两性功能的隔离方式及其适应意义。云南草蔻(Alpinia blepharocalyx)操控授粉实验表明, 自花花粉对其异交率影响不显著(P > 0.05), 但可能由于自花花粉沉降导致胚珠贴现进而引起近交衰退, 操控条件下每果结籽数显著减少(P < 0.01)。云南草蔻和红豆蔻(Alpinia galanga)花粉管生长实验都显示无论对两种表型进行怎样的授粉处理, 花粉粒萌发和花粉管生长的速率仅在柱头处于可授位置时表现出最大值, 与自交和异交授粉方式无关; 上举型植株上午花粉囊虽未裂但其内花粉已成熟。研究结果表明即使不考虑花柱运动, 山姜属植物也具有异型雌雄异熟的特性。这一结果证实了花柱卷曲运动机制是通过互补式雌雄异位和异型雌雄异熟相结合形成的花部二态性, 异型雌雄异熟促进了异交, 而花柱运动的功能可能在于避免雌雄干扰。     

胭脂花野生居群花粉形态多样性研究

胭脂花是分布于中国北部的报春花科报春花属花柱二型植物,为了阐明胭脂花花粉形态的多样性,对胭脂花分布范围内的7个野生居群的花粉形态进行了测定。结果表明,胭脂花花粉属N3P4C5型,极面观多为三角形,具三孔沟,少数为四边形,具4孔沟;短花柱植株的花粉粒较大(16.53×17.58μm),花粉粒外壁粗糙,表面纹饰多,网眼大;长花柱植株的花粉粒较小(12.95×13.72μm),花粉粒外壁较光滑,表面纹饰少,网眼小。不同居群间花粉粒在大小、网眼直径、外壁纹饰等方面存在显著差异,花粉形态变异系数在4.88%~35.48%之间;短花柱类型各居群的平均变异系数为16.18%,居群间差异较大,其中庞泉沟居群变异系数最大(24.05%),海坨山居群最小(10.13%);长花柱类型各居群的平均变异系数为14.89%,庞泉沟居群的变异系数最大(19.75%),五台山与海坨山居群最小(12.50%),长花柱类型的花粉性状比短花柱植株更为稳定。UPGMA聚类分析发现,7个居群聚为两大类,除庞泉沟居群外,其他居群聚为一组,地理距离相近的居群一般聚在一起。研究结果为胭脂花种质资源遗传多样性及育种研究提供了依据。     

红豆蔻专性异交主导下的主动自交机制（英文）

主动自交一直以来都被认为是植物在面对极端环境,例如传粉者稀缺的情况下所采取的繁殖保障机制,它不利的一面主要表现为近交衰退和花粉或胚珠贴现。在姜科植物部分属,如山姜属和豆蔻属当中,存在着一种被称作花柱卷曲(flexistyly)的特殊机制。过去的研究认为这种机制的意义在于避免自交和性别干扰,但是根据我们的野外观察,如果下垂型花朵的花粉在其花柱开始向下弯曲时仍然留在花药之上,柱头就很有可能接触到花粉从而完成主动自交。为此我们探索了红豆蔻(Alpinia galanga)的繁殖系统,研究结果表明:(1)红豆蔻自交亲和,并存在一定的近交衰退;(2)上举型为异交,较之下垂型投入了更多的资源;(3)上举型的花粉胚珠比显著低于下垂型,由于红豆蔻的胚珠数是固定的六枚,故两种表型花粉胚珠比的差异反映了其花粉数目的差异。这可能与上举型仅仅为下垂型提供花粉,而下垂型除为上举型提供花粉外,还需要有足够的花粉以备自交所需。因此,红豆蔻当中存在主动自交机制,并且其花柱卷曲机制在避免不必要的自交和性别干扰的同时,也为作为繁殖保障所必需的延迟主动自交创造了有利条件。同时通过控制主动自交发生的时间达到避免三种功能之间的相互冲突。这种只在姜科植物当中存在的特殊机制充分展示了其进化过程中对不利环境的适应。     

基于cpDNA单倍型多态性的草果栽培地理起源证据

为了探索草果(Amomum tsaoko)的栽培地理起源,该文检测了草果、拟草果(A. paratsaoko)的cpDNA序列变化,并获取了单倍型多态性信息。结果表明:(1)20个草果居群272个植株、5个拟草果居群62个植株共检测到7种单倍型。其中,草果有3种单倍型(H1、H3、H6),拟草果有6种单倍型(H1、H2、H3、H4、H5、H7)。H1和H3为共享单倍型,H6为草果私有单倍型,H2、H4、H5、H7为拟草果私有单倍型。H1为普通单倍型,H2为祖先单倍型。(2)草果居群遗传多样性远小于拟草果居群,遗传变异主要来源于居群内,拟草果居群主要来源于居群间。麻栗坡铁厂(TC)、屏边玉屏(YP)居群的遗传多样性、单倍型多样性高于其他18个草果居群。(3)进一步分析表明,包含屏边、马关、西畴、麻栗坡的云南东南部前端地域和邻接的广西那坡可能共同构成草果栽培驯化起源中心,以麻栗坡为核心区域,向周边的西畴、马关、屏边、那坡扩张。因此,结果显示应对TC、YP、那坡下华(XH)居群加以保护。该研究结果为草果种质资源保护、利用提供了遗传学信息。     

异质生境对二型花柱植物雪地报春花性状分化的影响

该研究以生长在新疆北部的二型花柱植物雪地报春(Primula nivalis)为研究材料,对7个低海拔(1 657~2 013m)森林居群和7个高海拔(2 400~2 700m)草原居群的花型比例进行调查,对花部特征进行检测,并对长、短花柱植株在不同海拔居群的花性状分化进行了比较研究,以揭示该类群植物的演化与环境的关系。结果表明:(1)在高海拔草原居群中长花柱植株比例高于短花柱植株。(2)比较草原和森林生态系统中的雪地报春居群,长花柱花形态特征间存在显著差异,但短花柱花形态特征间的差异不显著。(3)高海拔草原居群中长花柱花的花冠筒长度、雄蕊长度、雌雄蕊距离、雌雄异位程度以及雌雄蕊空间位置是导致花性状分化的主要因素。(4)在草原居群中,长花柱花的雄蕊、雌雄异位程度及花冠口至雄蕊距离的变化减少了长短花柱花间的互补式对应性。研究认为,在异质生境中长花柱花性状的变化是导致该物种长短花柱花性状分化的主要因素。     

艳丽耳草的二型花柱及异型自交不亲和系统

异型花柱是一种受遗传因素控制的花型多态性现象,包括二型花柱和三型花柱两种类型.本文以茜草科艳丽耳草(Hedyotis pulcherrima)为实验材料,通过对其野外居群的花型、花部形态及花粉特征等观察,发现艳丽耳草野外居群同时存在长花柱型花和短花柱型花,长/短花柱型花的数量比例为1∶1.两型花具有精确的交互式雌雄异位特征,并且该特征与花冠长度相关性显著.长/短花柱型花的柱头裂片长度、花粉大小及淀粉含量等具有二型性.花粉体外培养时花粉萌发率及花粉管生长速率无显著性差异.人工授粉后,艳丽耳草长/短花柱型花型间异交花粉管生长形态正常,授粉24 h后花粉管均已进入子房.而长/短花柱型花在自交及型内异交下均表现为不亲和,花粉管生长停止于柱头,花粉管顶端累积胼胝质并膨大.艳丽耳草没有无融合生殖现象,型间人工辅助异交授粉结实率为100％,显著高于自然结实率.本研究结果表明,艳丽耳草是典型的二型花柱植物,并具有异型自交不亲和系统.     

花柱卷曲性的维持及功能性别特化

花柱多态型的型比通过选型交配形成的负频率依赖的选择来维持。种群空间格局对于频率依赖选择所维持的花柱多态型是至关重要的。该研究使用摆放实验构建不同型比的马来良姜(Alpinia mutica)人工种群, 以评价花柱卷曲性促进选型交配的功能。使用邻域模型调查了云南草蔻(Alpinia blepharaocalyx)种群中的目标植株的坐果数、结籽数及其邻域中花序的数量和型偏以探讨在局域尺度上目标植株的雌性适合度是否受负频率依赖的选择。通过比较云南草蔻上举型和下垂型各繁殖性状的差异以及两型的功能性别的计算以评估两型功能性别可能存在的特化趋势。摆放实验结果说明花柱卷曲性形成的二型种群可以促进型间花粉传递。在局域尺度上, 云南草蔻两型倾向于同型聚集分布, 这一分布特点反映出其克隆生长特性。统计结果说明: 邻域中异型花粉供体相对丰富度对两型目标植株都无影响; 目标植株雌性适合度在邻域中不受负频率依赖选择的影响。这一结果并不支持负频率依赖的选择在该研究尺度上是影响种群型比结构的主要机制。云南草蔻两型个体在花期和果期的繁殖指标上不存在显著差异; 功能性别计算结果显示选型交配是种群内唯一的交配模式时, 下垂型功能性别偏雌性而上举型功能性别偏雄性。这一功能性别特化的趋势可能是通过对上举型的雄性功能的选择而造成的, 并可能与种群型结构相关。当功能性别计算只考虑自交而忽略近交衰退时, 种群功能性别偏向雌性。     

Effects of light and low temperature on the reciprocal style curvature of Flexistylous Alpinia Species (Zingiberaceae)

The style curvature (flexistyly) of Alpinia species in ginger family is a unique plant organ movement because the style of each flower curves twice during its 1-day anthesis and styles of two phenotypes of each Alpinia species in the same population synchronously curve in opposite directions at the same time. In this study, we investigated the effects of low temperature and light conditions on these reciprocal style movements. Our results indicate that low temperature cannot change the direction of each curvature movement, but can slow down these movements and decrease the curve degrees. Light did not affect the upward curvature of the cataflexistylous morph, but the degrees of downward curvature decreased in darkness. For the anaflexistylous morph, the downward curvature only occurred in darkness, but curved directly upward in light condition; after the first (downward) curvature, the second (upward) movement only occurred in light, but did not occur if styles maintained in darkness. These results suggest that low temperature does not stimulate style curvature; light is the necessary condition for the upward movement of the anaflexistylous morph. The stimuli that induced curvature movements in the two morphs were different. Both two curvatures of the cataflexistylous style and downward movement of the anaflexistylous style were controlled via an endogenous program, while the upward movement of the anaflexistylous style was controlled by light.     

Adaptive significance of flexistyly in Alpinia blepharocalyx (Zingiberaceae): a hand-pollination experiment

BACKGROUND AND AIMS: Flexistyly is a sexual dimorphism where there are two morphs that differ in the temporal expression of sexual function and also involve reciprocal movement of the stigmatic surface through a vertical axis during the flowering period. The adaptive significance of flexistyly has been interpreted as a floral mechanism for outcrossing, but it may also function to reduce sexual interference in which styles and stigmas impede the pollen export. Here these two explanations of flexistyly were tested in Alpinia blepharocalyx through a hand-pollination experiment. METHODS: Hand-pollinations were performed in two temporal morphs and consisted of two sequential pollination treatments, namely self-pollination in the morning and inter-morph pollination in the afternoon (treatment 1) or conversely inter-morph pollination in the morning and self-pollination in the afternoon (treatment 2), and two simultaneous self- and inter-morph cross-pollination treatments either in the morning (treatment 3) or in the afternoon (treatment 4). Seed paternity was then determined to assess relative success of self- versus cross-pollen using allozyme markers. KEY RESULTS: In the sequential pollination treatments, whether the stigmas of recipients are receptive in the morning is crucial to the success of the pollen deposited. When the cataflexistylous (protandrous) morph served as pollen recipient, early-arriving pollen in the morning can sire only a very small proportion (<15%) of seeds because the stigmas were then unreceptive. However, when the anaflexistylous (protogynous) morph served as pollen recipient, early pollen did gain a large competitive advantage over the late pollen, particularly when cross-pollen arrived first. Simultaneous self- and inter-morph cross-pollination indicated that outcross-pollen is more competitive than self-pollen on receptive stigmas. CONCLUSIONS: Differential maturing of male and female organs in Alpinia blepharocalyx is sufficient for selfing avoidance, obviating the need for style movements. Instead, the upward style curvature of the cataflexistylous morph in the morning and the anaflexistylous morph in the afternoon most likely represents a means of reducing interference with pollen export.     

Reproductive biology of Alpinia blepharocalyx (Zingiberaceae): another example of flexistyly

The floral biology and breeding system of Alpinia blepharocalyx were studied in Yunnan province, southwest China. Our results indicate that populations of A. blepharocalyx have two floral morphs, which differ in flowering behaviour: the cataflexistylous morph in which the stigma is held erect above the dehiscent anther when anthesis begins in the morning and becomes curved under the anther at afternoon, and the anaflexistylous morph in which the receptive stigma is curved under the indehiscent anther first and moves into a reflexed superior position above the anther as it begins to shed pollen in the afternoon; the flowering period of both floral morphs is 12 hours; the stylar movements in the two floral morphs are synchronous, and they have similar traits to those found in other Alpinia species previously reported. Also, on average, cataflexistylous flowers are larger than anaflexistylous flowers, especially the labellum and corolla tube length; moreover, the P/O ratio of the two floral morphs is significantly different: the cataflexistylous morph has more pollen grains and fewer ovules than the anaflexistylous morph; the evolutionary significance of this comparison is discussed. Cataflexistylous flowers were observed to produce a lower concentration of nectar than that of anaflexistylous flowers before 11:00 a.m., but they then have higher nectar concentration; cataflexistylous flowers always have more nectar than anaflexistylous flowers. Flowers of A. blepharocalyx were visited by fewer insects at a lower frequency, including honey bees (Apis cerana cerana) and two species of carpenter bees (Xylocopa spp.). No significant differences were found in the fruit set among the hand-pollination treatments regardless of selfing (geitonogamy and autogamy) or crossing (intermorph and intramorph); but all hand-pollination treatments exhibited much higher fruit set than the controls; meanwhile, no fruit set occurred in the unpollinated bagged plants. Pollen tube growth was examined using fluorescence microscopy following self, intramorph, and intermorph hand pollinations at different times of the day; the pollen tubes of both floral morphs have the same growth rate and the capability to reach the ovary. Both the results of pollen tube growth and fruit sets under different pollination conditions show that A. blepharocalyx is self-compatible and dependent upon insects for pollination. The distinctive flexistyly mechanism of A. blepharocalyx is likely a floral mechanism that promotes effective intermorph pollen transfer.     

Why do stigmas move in a flexistylous plant?

Flexistyly is a recently documented stylar polymorphism involving both spatial and temporal segregation of sex roles within hermaphroditic flowers. Using the experimental manipulation of stigma movement in self-compatible Alpinia mutica, we tested the hypothesis that selection for reducing interference between male and female function drives the evolution and/or maintenance of stigma movement. In experimental arrays, anaflexistylous (protogynous) flowers served as pollen donors competing for mating opportunities on cataflexistylous (protandrous) flowers. The pollen donors were either manipulated so their stigmas could not move or were left intact, and their success was determined using allozymes to assess the paternity of recipient seeds. We found that manipulated flowers sired a significantly smaller proportion of seeds, showing that stigma movement in unmanipulated plants increased male fitness. This result was strongest under conditions in which pollen competition was expected to be highest, specifically when pollinators visited multiple donor plants before visiting recipient flowers.     

Effects of indole-3-acetic acid and auxin transport inhibitors on the style curvature of three Alpinia species (Zingiberaceae)

The effects of indole-3-acetic acid (IAA) and the auxin transport inhibitors 2, 3, 5-triiodobenzoic acid (TIBA) and 1-N-naphthylphthalamic acid (NPA) on the style curvature of Alpinia platychilus, A. blepharocalyx, and A. mutica were studied. Exogenous IAA stimulated the style curvature movement of the anaflexistylous morph (ana-morph) and cataflexistylous morph (cata-morph) of three Alpinia species in light, but had no effect in the dark. Treatment with auxin efflux inhibitors (NPA and TIBA) before flower opening did not affect the first curvature of the two morphs in darkness; however, the subsequent second movement of the ana-morph was enhanced by NPA or TIBA, while the second movement of the cata-morph was completely inhibited. After the first curvature, NPA and TIBA treatments at 06:00?hours (before significant illumination) and 11:00?hours (after the styles were illuminated for 4?h) increased the second curvature of the ana-morph, but significantly decreased that of the cata-morph. The effect at 06:00?hours was more significant than the effect at 11:00?hours. These results suggested that auxin and auxin transport affected the style curvature in a different way in the two morphs, and two morphs had distinct mechanisms for style movement at different times.     

Evolutionary maintenance of stigma-height dimorphism in Narcissus papyraceus (Amaryllidaceae)

Stigma-height dimorphism is a sexual polymorphism in which plant populations are composed of two floral morphs that differ significantly in style length but not anther position. The morphs exhibit approach and reverse herkogamy, floral designs that in most species typically occur as monomorphic conditions. We investigated the floral biology of stigma-height dimorphism in the Mediterranean geophyte Narcissus papyraceus (Amaryllidaceae) in an effort to understand the evolutionary forces maintaining stylar polymorphism. Our survey of 66 populations in Spain, Portugal, and Morocco indicated that 56% were dimorphic with the long-styled morph at an average frequency of 0.79. The remaining 44% of populations sampled were monomorphic for the long-styled morph. In dimorphic populations there was a significant positive relation between population size and the frequency of the short-styled morph. Controlled pollinations demonstrated that N. papyraceus is self-sterile with no significant differences in female fertility between intra- and intermorph crosses. Prior self-pollination reduced seed set in flowers that were subsequently cross-pollinated. Estimates of mating patterns using allozyme markers in eight populations indicated that N. papyraceus is largely outcrossing (mean t(m) = 0.81) with no significant differences between monomorphic and dimorphic populations or style morphs. Stigma-height dimorphism in N. papyraceus is maintained in populations by insect-mediated cross-pollination with biased morph ratios and stylar monomorphism likely resulting from the combined influence of the inheritance of the polymorphism, morph-specific differences in assortative mating and founder effects.