长萼兰花蕉(Orchidantha chinensis var.longisepala)的繁育系统研究

通过野外观察并采用杂交指数（OCI）测定、花粉/胚珠比（P/O）检测、人工控制授粉等方法,对长萼兰花蕉（Orchidantha chinensis var.longisepala（D.Fang） T.L.Wu）种群的繁育系统进行了研究,采用常规石蜡切片与扫描电子显微镜（SEM）观察了柱头与"V"形黏盘的结构与形态。结果表明,长萼兰花蕉单花花期一般为18 d,依其花部形态的变化可分为蕾期、花萼未反转期、花萼反转期、唇瓣枯萎期、花萼枯萎期5个时期;根据杂交指数值为4、P/O值为253.89 ±21.09、人工异花授粉结实率分别为45%（2014年）和75%（2015年）,显示出长萼兰花蕉的繁育系统属于异交,且需要传粉者。石蜡切片观察到长萼兰花蕉黏盘区与柱头可授区之间是光滑的表皮细胞,结合人工授粉实验与分泌物含糖量测定结果表明,长萼兰花蕉的"V"形黏盘不具有可授性,其作用可能是分泌黏液附着在传粉者背部使其便于携带花粉。长萼兰花蕉整个花期环境湿冷、多雨且开花同步性较低,这些因素很可能造成其有效传粉媒介缺乏,影响了传粉成功;另一方面,长萼兰花蕉有性繁殖受到限制,其主要通过根状茎进行无性繁殖后代,所以分布范围比较狭窄。     

Submarine pollination in the marine angiosperm Zostera marina (Zosteraceae). II. Pollen transport in flow fields and capture by stigmas

Flow chamber observations of the filamentous pollen of Zostera marina L. (Potamogetonales) revealed that pollen rotated and moved toward inflorescences where they were captured by stigmas. The mechanics of this abiotic pollination process were examined and found to be related to the flow environment around emergent flowers. The translational movement of pollen was imparted by the advection of the fluid (e.g., pollen kinetic energy, K, ranged from 0.8 x 10-14 to 2.4 x 10-14 J, and the average K of the fluid was _ 0.7 x 10-14 J), while the rotational motion was imparted by the fluid shear stress (tau) within the velocity gradient (e.g., pollen shear stress, sigmat = omegamu where omega is the rotational velocity and mu is the dynamic viscosity, ranged from 3.4 x 10-4 to 26 x 10-4 Pa, and the average fluid shear stress was tau _ 10 x 10-4 Pa; Ackerman, 1997, American Journal of Botany 84: 1099-1109). These results indicate that there is a greater potential for pollination by filamentous pollen relative to spherical pollen. Functionally, while spherical pollen needs to be directly upstream from stigmas to be captured, filamentous pollen need only be in the vicinity of inflorescences and flowers to be captured by stigmas. Thus, in addition to direct interception on stigmas, filamentous pollen can be captured while they rotate past flowers or when they are redirected through the velocity gradient towards flowers. Filamentous pollen is an adaptation to submarine pollination in seagrasses.     

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）.     

水稻受精前后胚囊内钙调素分布的变化：免疫金电镜观察

用胶体金免疫电镜技术观察了水稻 (Oryzasativasubsp .japonica)受精前后胚囊内钙调素的分布变化。授粉后 ,卵细胞、助细胞和中央细胞内的钙调素较授粉前均有所增加。中央细胞内钙调素的增加要比卵细胞中约早 2h ,退化助细胞与宿存助细胞之间的钙调素含量无明显差异。授粉到受精期间 ,钙调素的主要分布形式由分散的单颗粒转变为聚集颗粒 ,受精完成后再变为分散的单颗粒形式。胚囊壁及珠心细胞的细胞壁和胞间隙中也观察到钙调素的分布和数量变化。初步讨论了胞内和胞外钙调素在水稻受精与合子形成中的作用。     

沙丘稀有种准噶尔无叶豆花部综合特征与传粉适应性

植物花部特征进化与传粉适应性一直是进化生态学领域关注的核心问题之一。以古尔班通古特沙漠自然生长的准噶尔无叶豆为对象,对其花部特征和传粉特性进行了野外观察和室内的分析研究。结果表明:种群花期历时21 d,花序花期历时7-12 d,单花花期一般3 d,若遇阴雨天气,花期可延长1-2 d,整个花期龙骨瓣一直保持闭合状态。单花10枚花药在旗瓣微张时已全部完成散粉。准噶尔无叶豆主要靠分泌花蜜、鲜艳的花色以及旗瓣基部的黄色辐射状纹理结构吸引传粉者。准噶尔无叶豆花期的有效传粉者为4种蜂类昆虫,它们的平均访花频率为(7.75±0.57)次·花^-1·d^-1,访花高峰期表现为三峰型: 13:00-14:00,16:00-17:00和19:00-20:00。准噶尔无叶豆人工套袋实验表明该种为自交亲和型,主动自交少见,生殖成功依赖传粉者。胚珠成功受精至果实完全成熟阶段存在自交衰退,柱头角质层结构和花粉刷结构是准噶尔无叶豆在进化过程中形成的减少自交,倾向异交的机制。     

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。     

浅谈传粉生物学中几个术语的含义及其中文译名

准确理解外来的专业术语并给予合适的中文译名,不仅有助于推动学科的发展,而且有利于同行之间的交流。传粉生物学是近年来在我国迅速发展的一个生态学与进化生物学的分支领域。本文讨论了该学科中的几个重要术语的含义和它们的中文译名,建议将pollen discounting和seed discounting译为“花粉折损”和“种子折损”,herkogamy译为 “雌雄异位”,trade-off译为“权衡”。     

授粉方式对铁皮石斛种质座果及种子萌发的影响

为进行铁皮石斛(Dendrobium officinale)的良种选育和种苗生产,对46个铁皮石斛种质进行人工授粉试验,研究了不同授粉方式的授粉成功率、座果率和种子的萌发能力。结果表明,4种授粉方式的授粉成功率明显不同,不同种质间的授粉成功率可达100%,且座果率普遍较高。只有31.3%的种质可以成功自花授粉,且座果率相差较大。同株异花授粉和种质内异株授粉的成功率和座果率均介于上述二者之间。授粉后所得种子的萌发率和萌发速度在4种授粉方式间也呈现与授粉成功率和座果率一致的趋势。这表明在铁皮石斛种质中存在自交不亲和现象,因此以不同产地来源的铁皮石斛种质为亲本进行人工授粉,可大大提高授粉的成功率和座果率,以及后代种子的萌发能力。     

露蕊乌头(毛茛科)不同海拔居群的传粉生态学

对青藏高原东北部两个不同海拔地点（互助,2460m和海北,3200m）的露蕊乌头Aconitum gymnandrum的传粉生态学进行了比较研究。研究结果表明高海拔居群的单花花期、雄性期持续时间、雌性期持续时间比低海拔长。露蕊乌头不存在无融合生殖现象,尽管高度自交亲和,但产生种子必须依赖传粉媒介。熊蜂是露蕊乌头的主要传粉昆虫,两个居群均存在传粉限制。熊蜂取食花蜜为主,在同一个花序上的访问顺序以由下向上为主,但在互助居群和海北居群有3．9％和2．7％的访花是由上向下进行的。统计发现有37．7％和29．3％的访问行为发生在同一植株内;因此,同株异花传粉造成的自交在露蕊乌头中仍然不能避免。低海拔居群的熊蜂种类和访花频率均高于高海拔居群,但自然状态下两个居群的结实率并没有显著差异。高海拔露蕊乌头居群可能具有较长的柱头持续时间,从而补偿了由于访花频率低带来的结实率降低。