野慈姑花粉限制评估的影响因素

以野慈姑为材料,研究补充授粉的处理水平(单花、花序)和花粉质量(自花花粉、异花花粉)对花粉限制评估的影响.结果表明: 补充授粉的处理水平会造成花粉限制的程度不同(P=0.0021),单花水平的授粉会导致花朵之间的资源重新分配,从而影响结实;补充授粉的花粉质量会对结实造成影响,补充异花花粉比自花花粉能产生更多的种子(P=0.0497),且萌芽率更高(P=0.0428),表明该体系的花粉限制不是数量的限制,而是优质花粉的限制.不同的试验水平和花粉质量可能对花粉限制的评估造成影响,相关研究应尽量对整个花序或者植株进行补充授粉,材料允许时还应考虑自异花粉的对比试验,有利于更客观地认识和检测花粉限制.     

野慈姑和矮慈姑种间花粉传递与生殖干扰不对称性

本研究观测了两种慈姑属(Sagittaria)植物野慈姑(S.trifolia L.)和矮慈姑(S.pygmaea L.)共享传粉者的种间访花活动,利用染色示踪方法检测了种间花粉传递是否存在及其强度,通过统计二者在单生/混生样地中的结实情况判断物种间生殖干扰存在与否,以及对植株有性生殖成功率的影响。结果显示：(1)主要共享传粉者存在种间访花行为,但访花者种间运动频率显著低于种内运动,且对野慈姑雄花存在访花偏好。(2)在混生样地中野慈姑和矮慈姑的雌蕊群上均能检测到共享传粉者带来的种间花粉传递,约1.4%的柱头上落置了染色标记的异种花粉;野慈姑花粉散布于矮慈姑花上的距离较远,数量较多,而矮慈姑花粉主要表现为近距离传递。(3)两物种在自然生境中共存时,矮慈姑种子不完整胚比例显著增加,而野慈姑完整胚比例维持在80%以上,表现为种间生殖干扰的不对称性。此外,本研究还对减轻生殖干扰的生态机制进行了探讨。     

交配距离与父本数量对野慈姑有性繁殖的影响

植物的有性繁殖是生活史和进化的核心, 母本及环境对繁殖的影响固然重要, 父本的贡献亦不容忽视。父本来源与多样性对坐果结籽和后代质量的影响明显, 但由于不同物种或种群的繁殖特点和进化历程, 往往也会呈现其独特性。该研究旨在探究挺水植物野慈姑(Sagittaria trifolia)是否存在自交或远交衰退, 以及父本数量对其繁殖和后代表现的影响。通过人工控制授粉, 设置自交、近距离异交(<50 km)、远距离异交(＞200 km) 3种交配距离以及单、双两类父本数量, 共计5种授粉处理, 观测野慈姑坐果概率、单果种子数量、种子面积、萌发率(2018和2019年)、幼苗芽长(2018和2019年)共7项指标。结果显示: 不同距离的交配对野慈姑的坐果概率、单果种子数量、种子面积、萌发率、幼苗芽长没有显著影响, 野慈姑未出现明显的自交衰退或远交衰退现象。父本数量的增加对野慈姑的结实数量(坐果概率、单果种子数量、种子面积)无影响, 但结实质量方面, 双父本处理的种子萌发率略高于单父本处理。综上所述, 交配距离与父本数量对野慈姑的繁殖表现影响较小, 这可能与其频繁的自交历史、远距离的基因扩散以及高度相似的水生环境有关; 同时, 该研究基于20余个自然种群的基因型, 研究结果也表明了野慈姑物种水平有性繁殖的优异和稳定性。     

拟南芥授粉前后花粉与乳突细胞的超微结构

利用透射电子显微镜技术,对自交亲和植物拟南芥授粉前后花粉和乳突细胞的超微结构进行了观察。发现花粉和柱头乳突细胞一些未经报道的超微结构特征,可能与拟南芥花粉和乳突细胞的识别及花粉管生长相关:(1)成熟花粉中,电子透明的、体积较大的小液泡(直径200～1000nm)呈均匀分布。部分小液泡内含有多层膜状结构物质,推测可能是膜的一种储存形式,与花粉萌发时大量出现的小囊泡有关。(2)花粉萌发时,小液泡由均匀分布变为不均匀分布。(3)授粉前后的乳突细胞顶端和侧端的内壁上有明显的壁内突结构,粘附的花粉开始萌发时的乳突细胞壁内突处可观察到直径50～100nm的小泡存在,表明拟南芥乳突细胞具有一定的分泌功能。     

烟草脱外壁花粉人工萌发与离体授粉实验系统的建立

通过花蕾低温处理、花药漂浮培养与花粉短时酶解程序可脱去花粉外壁,分离出烟草(Nicotianatabacum L.)的脱外壁花粉。研究了分离过程中的酶液渗透压、培养基中聚乙二醇(PEG)与蔗糖以及添加水解乳蛋白等因素对脱外壁花粉人工萌发的影响。在含30％PEG-6000与0.1％水解乳蛋白的D_2培养基中,萌发率最高达57.8％;花粉管生长正常,培养24h后一半以上的花粉管中生殖细胞分裂成精子。用微滴和贴滤纸小片的方法将30～40粒脱外壁花粉授予柱头上,近一半能萌发花粉管并在花柱中生长。采取授粉后子房培养方法,获得了种子与幼苗。从而建立了脱外壁花粉离体授粉实验系统。讨论了脱外壁花粉人工萌发与离体授粉实验系统的建立对于研究外壁在花粉萌发中的生物学功能以及开拓新的转基因技术等方面的意义。     

原始隐羊齿(Cryptonoclea primitiva)花粉形态和气囊个体发育的观察*

传统观念认为ＧＳＰＤ组合始于中二叠世孔谷期,据新疆等地资料证实此类组合的出现要早得多。准噶尔盆地在Ｐｒｏｆｏｓｕｌｉｎｅｌｌａ－Ｐｓｅｕｄｏｓｔａｆｆｅｌｌａ带之下和相当层位的晚石炭世早期地层中存在两个孢粉组合,即（１）早巴什基尔期巴塔玛依内山组的Ｒｅｍｙｓｐｏｒｉｔｅｓ＾＊ｕａｒｉｃｕｓ－Ｓｔｒｉａｔｏｌｅ－ｂａｃｈｉｔｔｅｓ ｊｕｎｇｇａｒｅｎｓｉｓ组合（Ｐｒｏ－ＧＳＰＤ）和（２）中晚巴什基尔     

油菜花粉发育相关基因RALFbn的克隆与表达分析

根据美国NCBI数据库中快速碱化因子(RALF)类基因序列的已知信息,克隆了油菜的快速碱化因子基因RALFbn,对其核酸序列及预测蛋白进行了生物信息学分析,并在油菜多种组织内观测其表达情况.结果表明:(1)经克隆获得油菜RALFbn基因的cDNA序列全长为510 bp,无内含子,编码79个氨基酸.(2)生物信息学分析发现,油菜RALFbn蛋白具有RALF类蛋白保守的“YIXY”区和4个保守的半胱氨酸残基,并且含有N豆蔻酰化位点、酪氨酸激酶Ⅱ磷酸化位点、蛋白激酶C磷酸化位点、和酪氨酸激酶磷酸化位点等多个生物活性位点,说明该蛋白在油菜中潜在的生理调节能力较为活跃.(3) RT-PCR检测RALFbn基因在油菜生殖器官中的表达结果发现,RALFbn主要在油菜雄蕊中表达,而在雌蕊、花瓣和萼片中没有表达.提示RALFbn基因极可能与油菜雄蕊中花粉的发育相关.     

珍稀濒危植物距瓣尾囊草(Urophysa rochkii)的开花物候和繁育系统特性

通过野外观察,运用套袋授粉和联苯胺-过氧化氢法等实验方法对距瓣尾囊草开花物候以及种群的繁育系统特性进行研究。研究结果:1)距瓣尾囊草为两性花,聚伞状花序,花期较长,从头年12月持续到次年4月,单花花期持续8—15 d,种群花期可持续4个月左右。2)距瓣尾囊草在花朵未开放前花粉没有活力,花药开裂当天花粉活力达到94.8%,第2天为90.3%,第3天为81.6%,第4天为62.9%,此后其花粉活力明显减弱;柱头可授性于散粉后第3天开始出现,散粉后4—5天最强,散粉后第8天柱头失去可授性;柱头可授性和花粉活力有5 d左右的重叠期。3)其花粉胚珠比P/O为938.5±250,按照Cruden标准划分,其有性繁育系统为兼性异交。4)按照Dafni的标准,距瓣尾囊草的OCI=4,即繁育系统为异交、部分自交亲和、需要传粉者。5)人工异花授粉结实率达80%以上,略高于自然结实率78.94%;直接套袋结实率为5.71%;去雄套袋和去雌套袋均不结实。以上结果表明,距瓣尾囊草繁育系统表现为异交为主、部分自交亲和并且不存在无融合生殖现象,其开花物候、花部特征和繁育系统为适应特殊的环境提供了一定的生殖保障,本次研究结果为距瓣尾囊草的迁地保护和种群的繁衍复壮提供理论依据。     

野油菜黄单胞菌(Xanthomonas campestris)L4胞外多糖的理化分析

本文报道野油菜黄单胞菌(Xanthomonas campcstris)L4以蔗糖为底物在2吨发酵罐中生产的胞外多糖的理化分析结果,并与美国的商品黄单胞菌多糖(Xanthan)相比较。两种多糖纯化后单糖组分的气相色谱分析表明,它们均含有D-葡萄糖和D-甘露糖,克分子比为1：1。糖醛酸含量相同,为19％。 L4多糖和Xanthan的丙酮酸含量也相当,分别为4．23％和4.66％,元素分析和红外光谱分析表明,它们有相似的元素组成和基团吸收。L4多糖的沉降系数S02。W为11．5-11．9 S,比美国商品高(10．10S)。L4多糖的持性粘度[η]=11．8dl／g,偏比容-v=0．55ml／g,分子量为2 2 25 600—378 3000。     

生长素与乙烯对兰花授粉后花发育的调节作用(英文)

以朵丽蝶兰为材料,对乙烯和生长素调节的授粉后花的发育进行了研究。实验结果显示,切花和植株上的花授粉后,乙烯的产生和花的发育无明显差异;花瓣的衰老、子房发育、花粉萌发和花粉管的伸长受乙烯调节;与切花相比,植株上花的子房内无ＡＣＣ合酶和ＡＣＣ 氧化酶ｍＲＮＡ 的积累。用生长素运输抑制剂２ ［（１ｎａｐｈｔｈａｌｅｎｙｌａｍｉｎｏ）ｃａｒｂｏｎｙｌ］ ｂｅｎｚｏｉｃａｃｉｄ（ＮＰＡ） 处理柱头,授粉诱导的子房发育在很大程度上受到抑制, 表明授粉后子房的发育需要转运来的生长素。     

两种生境下野慈姑繁殖差异及其机制

植物的生长环境不但可直接作用于其可利用资源的多寡及其繁殖分配,而且可通过影响植物所在的群落以及传粉者的组成或行为而间接的导致繁殖差异。然而,直接与间接作用的方向或强度很少被同时关注,从而限制了从机制上理解环境对植物繁殖的影响。选取野慈姑(Sagittaria trifolia L.)为研究材料,将相同基因型组成的植株分别种植在光照差异明显的两个同质园(林荫区与日照区),于盛花期对野慈姑的开花数量、昆虫访花进行了观察,确定其主要访花昆虫、记录访花行为以及野慈姑的繁殖产出水平。研究表明,日照区野慈姑每天开放的花朵和植株数量显著高于林荫区。两个区域内野慈姑的主要访花者有四大类:蚜蝇类、蜂类、蝶类和蝇类;其中林荫区的主要传粉昆虫为蚜蝇类,而日照区为蜂类。日照区昆虫单位时间内的访花频率、昆虫每回合访问的雄花数、总花数和花序数均显著高于林荫区。日照区野慈姑的座果率显著高于林荫区,而单果种子数量与种子面积与林荫区相当。总体而言,日照区野慈姑的繁殖产出达到了林荫区的三倍以上,这是环境的直接作用与环境介导的传粉作用在同一方向上叠加的结果,且前者占主导地位。在关注植物、物理环境和生物因子三者之间互作的前提下,量化每个繁殖阶段的水平,特别是传粉昆虫在不同生境下的表现,阐述了环境异质性导致植物繁殖差异的根本原因。     

The relationships between Poaceae pollination levels and cereal yields

We analyze the possible relationships between theannual levels of Gramineae pollination and cerealyields in Badajoz province (Spain). The pollinationparameters studied were the mean annual pollenconcentration and the concentrations of March, April,May, June, July, and August, and the yield parameterwas taken to be each crop's yield (in t/ha) as well asthe mean yield of all the province's cereal crops.The most notable results were: the relationshipbetween the June pollen concentrations and the yieldsof dryland cereals (wheat, barley, oats, rye, andtriticale), the lack of correlation between the pollenparameters and the yields of irrigated crops (maize,rice, and sorghum), and lastly the significantrelationship between the mean cereal yields and boththe mean annual pollination and the May and Juneconcentrations. At least in the case of the drylandcrops, these relationships are explained by thesimilarity in the effect of environmental conditionson both the wild flora and the cereal crops.     

Natural levels of pollination intensity and effects of pollen loads on offspring quality in females of Thalictrum pubescens (Ranunculaceae)

Females of Thalictrum pubescens produce stamens containing sterile pollen. Earlier studies have shown the presence of stamens does not increase seed set through increased visitation by insects. Insects may, however, increase pollen deposition on stigmas and increase pollen competition. This paper examines: 1) pollen deposition levels in natural populations and 2) whether larger pollen loads lead to higher quality offspring. The majority of stigmas in two populations received less than 15 grains, but a small proportion had large loads. The latter may represent the occasional insect visit. These visits may provide the opportunity for pollen tube competition. In the greenhouse, flowers receiving heavy-pollen loads had higher seed set than flowers receiving light-pollen loads. Seeds from the two treatments were the same mass, had similar germination times, and seedlings had the same mass. In conclusion, it does not appear that pollen tube competition can account for the maintenance of stamens in females of T. pubescens.     

Estimate and mapping of the activity of airborne pollen sources

Summary This contribution presents a procedure for estimating the distribution of pollen sources and mapping their activity. Particular reference is made to the example of mapping the pollen emissions ofCastanea sativa, in the Reno valley near Bologna (Italy), achieved with numerical techniques and starting from basic maps (vegetation, topographic and pedologic), phenological observations and pollen production data.     

Annual, daily and intradiurnal variation of Celtis pollen in the city of La Plata, Argentina

The behaviour of Celtis airborne pollenwas studied for a period of three years(1998–2000) in the city of La Plata. The pollengrains were captured with a Lanzoni trap andthe maximum pollination period was observed tooccur during the end of winter and spring inthe three years. The annual values of pollenconcentration varied, and a significantdecrease was observed during 2000. The greatestairborne pollen record was in October with anaverage of 82.3% in relation to its totalconcentration during 1998–2000. Based on theintradiurnal behaviour analysis, it wasobserved that the maximum pollination peakoccurs at 2H when the temperaturereaches its maximum values. Considering thethree sampling years, the meteorologicalvariables that most influenced the processes of pollen emission,dispersion and transportation in the atmospherewere: maximum and minimum temperature andrainfall.     

基于山地蜂蜜花粉组成的中华蜜蜂传粉多样性研究

中华蜜蜂为多种植物传粉,具有重要的生态服务价值。为进一步了解中华蜜蜂选择蜜粉源植物的多样性与特征,采用聚合酶链式反应(PCR)、DNA条形码、高通量测序等技术,研究了源自陕西宝鸡、贵州望谟和广西凤山蜂巢蜜中的花粉来源。通过对样品花粉rbcL基因片段扩增及测序、分析,发现各样本间可操作分类单元(OTU)水平上蜜粉源植物Alpha多样性指数无显著差异,同一地点样品不同重复间存在较高的相关性,而不同地区样本相关性较低。三地共鉴定出27目46科71属82种蜜粉源植物,其中宝鸡市、望谟县、凤山县样本中分别鉴定出57种、30种和40种,各地蜜粉源植物的物种组成存在较大差异。这些蜜粉源植物中,菊目植物种类最多,其次为毛茛目,分别有12种和7种。其中草本植物和木本植物(含乔木、灌木和木质藤本等)分别有44种和38种。研究对蜜粉源植物花序特点进行了分析,但并未发现相关性状对中华蜜蜂选择具有的影响。从属的区系成分分析,总体上温带分布区类型的植物属多于热带分布区类型的属,所占比例分别为46.5%和36.6%,但在凤山县样本中出现热带分布区类型多于温带分布区类型的情况。在不同样品中,红足蒿(Artemisia rubripes)、向日葵(Helianthus annuus)、芜青(Brassica rapa)、粗糠柴(Mallotus philippensis)、枇杷(Eriobotrya japonica)等分别占有一定优势,其与中华蜜蜂的关系值得进一步研究。根据蜜粉源植物的系统进化关系,中华蜜蜂访问的蜜粉源植物处于不同进化地位的分支,其中在菊类分支和蔷薇类分支比较集中。研究揭示了中华蜜蜂传粉植物组成特点,为进一步认知中华蜜蜂传粉服务功能的重要性提供依据。     

响应面法优化麻疯树花粉离体萌发培养基的研究

麻疯树因其种子含油率较高,种子油提炼的生物柴油可部分替代汽油,而成为一种极具潜能的能源作物,但由于产量低,麻疯树在热带、亚热带的发展受到极大限制。杂交育种是提高产量的重要手段,杂交亲本花粉生活力的高低直接影响到育种的成效。因此,寻求麻疯树离体花粉萌发的最适培养基配方,探明花粉萌发培养基中各主要培养基成分间的交互作用对生产上麻疯树杂交结实率和种子产量的提高具有重要意义。该研究以麻疯树开花初期雄花上花药刚散粉时的成熟花粉粒为材料,采用Box-Behnken设计(Box-Behnken design,BBD)的响应面法,对麻疯树花粉离体萌发培养基中各主要培养基成分的浓度配比及各主要培养基成分的交互作用进行了研究。以花粉萌发率为响应指标,建立了4种营养成分(蔗糖、硼酸、硝酸钙、硝酸钾)与花粉萌发率的响应面模型,并对各主要培养基成分的浓度配比进行了优化。通过R软件进行响应面分析的结果表明:4因素对花粉萌发率的影响顺序为蔗糖硼酸硝酸钙硝酸钾;蔗糖与硼酸、蔗糖与硝酸钙、蔗糖与硝酸钾之间的交互作用显著。响应面建模优化后的最佳培养基为13.77%蔗糖+32.14 mg·L~(-1)硼酸+22.21 mg·L~(-1)硝酸钙+19.95 mg·L~(-1)硝酸钾+200 mg·L~(-1)硫酸镁,在此条件下的理论萌发率为99.73%。采用此培养基成分配比得到麻疯树花粉离体试验萌发率为98.97%,与理论响应值相吻合,同时也表明利用BBD设计的响应面模型进行麻疯树花粉离体萌发培养条件优化方法的有效性。     

Transfer of pollinaria on birds’ feet: a new pollination system in orchids

We report the discovery of a new mechanism of pollination in orchids: transfer of pollinaria on the feet of birds. Observations carried out in South Africa and Malawi showed that the orchids Disa chrysostachya Sw. and Disa satyriopsis Kraenzl. are pollinated by sunbirds. Pollinaria of these orchids become attached firmly to the birds toes when they perch on the tall narrow inflorescences which are packed tightly with numerous small orange flowers. Birds typically perch on the lower part of an inflorescence while reaching up to feed on nectar in flowers on the upper part, but occasionally reverse this position to probe the lower flowers. The nectar is contained within a short bulbous spur with a narrow entrance that permits entrance of a sunbirds slender tongue. Contrary to expectation, the pollination mechanism in D. chrysostachya is remarkably efficient with about 6.1% of pollen reaching stigmas on other plants and fruit set occurring in 95% of flowers at one site. Birds seldom move their feet once perched, thus minimizing the incidence of self-pollination, either within or between flowers on an inflorescence.     

Pollination mechanisms and pollen-ovule ratios in someGenisteae (Fabaceae) from Southwestern Europe

We studied the biology and floral rewards of 34 taxa ofGenisteae from the SW of Europe. Most of the floral attributes show a statistically significant direct relationship. Anther biomass of the lower whorl (lW) is significantly lower than that of the upper whorl (uW), and the ratio of the two (Rv) differs among the taxa. All taxa are polliniferous, andRetama sphaerocarpa also secretes nectar. They can be considered xenogamous or facultative xenogams on the basis of their high pollen/ovule (P/O) ratios. Three principal mechanisms of pollen releasing are identified in this tribe: valvular, pump and explosive; the latter comprises specialized and nonspecialized subtypes. Pollination is sternotribic except in the specialized explosive mechanism, in which it is noto-sternotribic. Thus some pollen serves as food (pollen from the uW, which adheres to the ventral surface of the insect) and part of the pollen fulfils a polliniferous function (pollen from the lW, which adheres to the dorsal surface). Species that use a pump mechanism have very low Rv values (Rv=0.08–0.26); species with valvular or nonspecialized explosive mechanisms have Rv values between 0.24 and 0.58; those with a specialized mechanism of pollen presentation have high Rv values (0.6–0.76). In contrast to expectations, the highest P/O ratios appear in the specialized explosive system, which allows a single visit from the insect.