夜光藻有性繁殖研究进展

夜光藻是全球最主要的赤潮生物之一,也是我国近海常见的浮游甲藻。根据营养方式分为异养的红色夜光藻和混合营养的绿色夜光藻,前者广泛分布于温带和亚热带近岸水域,后者仅分布于热带西太平洋、阿拉伯海、阿曼湾和红海。夜光藻的生活史包括无性繁殖和有性繁殖过程。少部分营养细胞自发转变为配子母细胞,启动了有性繁殖。每个配子母细胞可形成大量配子,具有横沟、纵沟和2根鞭毛,形态与裸甲藻接近。配子两两融合形成合子,合子不经过休眠孢囊阶段直接发育成新的营养细胞。目前,对配子母细胞形成的调控机制、合子发育的影响因素的认识还存在分歧。研究发现,营养细胞经过一定次数的二分裂后都会转变为配子母细胞,而配子的存在能够中止此过程,使营养细胞继续进行二分裂。因此,有性繁殖可能通过产生新个体对种群增长做出贡献,还可能通过释放配子维持无性繁殖,进而促进种群增长。配子在相模湾水域全年都有分布,其丰度峰值与营养细胞丰度峰值同步或提前出现,配子的大量出现可能是赤潮形成的必要条件。对有性繁殖的研究佐证了夜光藻在甲藻的系统进化中处于较为古老的地位。此外,还简单介绍了研究夜光藻有性繁殖的主要方法,回顾了国内的夜光藻研究,并对相关研究进行了展望。     

天麻室内有性繁殖技术

天麻室内有性繁殖技术蔡义荣（安徽省金寨县双河职业高中２３７３８１）天麻（Ｇａｓｔ。ｄｉ４ｅｌａｔａＢｌｕｍｅ）属寄生性兰科植物,无根无绿叶,依靠分解吸收蜜环菌卜。。ｌｉａｎａｍｅｌｌｅａ（ＶａｈｌｅｘＦｒ）ＱｕｅｌＪ而生存。应用箭麻（即成熟的天麻块茎...     

玉蝉花繁殖生态学研究

通过野外调查、人工授粉和室内种子萌发实验等,对天目山玉蝉花（Iris ensata）种群繁殖生态特征进行了研究。结果显示：玉蝉花自然种群呈聚集型分布,种群更新主要依赖贡献率为0.756的无性繁殖。人工同瓣和异瓣自花授粉座果率分别为10%和20%,结实数分别为0和4±1（n=2）粒/果;同株和异株异花授粉座果率分别为80%和100%,结实数分别为59±7（n=8）和64±9（n=10）粒/果,自交主要来自同株异花授粉,而同株花异熟、雌雄异位和异向等可有效降低自交。自然套袋不结实,不存在无融合生殖。花粉/胚珠比1277±270（n=10）,辅证玉蝉花为兼性异花授粉、异花授粉植物。有效授粉昆虫为蜜蜂（Apismellifica）,访花频率为0.019次.花-1.h-1,单只蜜蜂回访同朵花的比率为3.5%。自然种群立地种子数估算值为368粒/m2,种子宿存,具非深度生理休眠,萌发需光,低温层积60d萌发率达94.9±0.7%。玉蝉花种群繁殖适应对策为k对策,具备自我维持机制,但现正受人为干扰。     

蓝睡莲有性繁殖栽培研究

蓝睡莲（延药睡莲）NymphaeastellataWilld．是一种具有园林水体绿化的重要观赏水生植物。根据我们调查、收集的结果看,现仅在海南省万宁县境内的丘陵湿地中发现有自然分布。中国植物志第二十七卷记载湖北有分布,但到目前为止,尚未有人报道发现实物;海南植物志记载海口市附     

蕨菜有性繁殖与无性繁殖技术

蕨菜有性繁殖与无性繁殖技术冯玉斌，何允波，赵占美，洪永刚（通化市园艺研究所１３４００１）蕨菜（ＰｔｈａｉｕｌｎａｑｕｆｆＩｎｕｍ）是凤尾蕨科的多年生草本植物。适应性强，分布极为广泛。近年来，我国对蕨菜进行大量出口。主要是由于其新鲜可口，营养价值高，含...     

藕莲有性繁殖栽培

根据莲(Nelumbo nucifera)生物学特性,既可用藕作种进行无性繁殖,也可用种子播种进行有性繁殖。藕莲在我国有数千年的栽培历史,但素以无性系栽培。尚未见到有性繁殖栽培的报道。作者自1980年起进行了有性繁殖栽培试验。1982-1984年先后在武汉市、河南省封丘县、进行大田小区栽培试验,并列入湖北省科委农林牧副渔综合基点县推广研究项目,在广济县试验推广,已获成功。     

野生有性繁殖物种首次证明可单性繁殖

通常都是2条蛇——一雌一雄——合作生下一窝蛇宝宝。然而最新的研究表明,美洲蝮蛇（Agkistrodon contortrix）及其有毒的表亲水蝮蛇（Agkistrodon piscivonus）却并非总是需要一个伴侣才能够创造下一代。这些毒蛇具有单．性繁殖的能力。     

风箱果有性繁殖研究

对风箱果（Physocarpus amurensis）适宜的采种时期、不同母树种子的成熟差异和幼苗的生长特征进行了研究。结果表明,风箱果种子的最适采种期在7月末,种子成熟后有休眠特性;方差分析表明,不同植株间种子的发芽率和千粒重都达到极显著水平（p<0.01）,并且发芽率与种子重量呈正相关,其相关程度最佳的为幂函数,确定系数是75.75%（p<0.01）;风箱果幼苗类型为子叶出土型,幼苗生物量对根的投资最大,其次是叶,茎的最少,在这3部分生物量投资中,对根和叶的投资比较稳定（其变异系数分别为6.8%和11.03%）,对茎的生物量投资具有较大的变异（其变异系数为21.81%）。基径是衡量风箱果幼苗空间大小的重要数量指标。风箱果构件生物量（根生物量、茎生物量、叶生物量及总生物量）各组分均随基径的增加,呈线性函数形式增长,这表明随着植株的空间扩展,各构件有着相同的物质生产与积累规律。     

毛红椿天然种群有性繁殖适合度及其繁殖更新

以九连山国家自然保护区毛红椿4个天然种群为研究对象,于2006—2016年调查毛红椿有性繁殖和自然更新的情况,分析其繁殖适合度系数和个体水平适合度.结果表明:九连山毛红椿各地理种群结实单株的初始数量较少(3~9株),经70余年的繁衍发育,现存结实单株的数量仅2~10株,且来源于原始单株或子1~2代.不同种群间有性繁殖差异显著,但结实能力呈逐年下降的趋势;随群落发育成熟,土壤种子库保存与种子萌发的失利,导致能正常生长发育成熟的林木数量近乎为0.毛红椿最佳性成熟年龄为40年,早期优势明显,适合度系数早期快速增长,为2.0~2.8,但急剧减少至0.3~0.5,之后较平稳减速至近乎于0;种群间个体有性繁殖适合度(0~14株·cm2)存在较显著差异,但均较低,甚至低至0;以现有繁殖率计算,有性繁殖与更新的适合度实测值均远低于预估值.总之,受有性繁殖遗传适合度低的影响,不同种群间有性繁殖与更新能力趋同衰退;个体有性繁殖适合度进一步降低且面临更高的投资风险,现有繁殖体系因此失衡并趋于恶化.建议开展繁殖交配、授粉结实及遗传多样性评价研究,同时人为干预林分环境,于结实期清理林地枯落物,在幼苗至幼树生长过渡期适当疏伐.     

性选择与性冲突理论在植物繁殖生态学中的应用与进展

性选择与性冲突是植物繁殖性状多样性及性系统演化的重要动力, 二者密切相关却又有所区别, 理解它们的作用机制及其影响对于植物繁殖生态学的研究具有重要意义。当前, 性选择与性冲突理论在植物繁殖生态学中的运用已取得长足进展, 但国内相关研究较少, 对该领域关注不够。因此, 该文对该领域的基本理论和研究进展进行了综述。首先, 阐述性选择与性冲突理论在植物研究中的发展及其运用基础; 其次, 分别从授粉前和授粉后两个阶段详细介绍性选择与性冲突在有花植物繁殖过程中的作用机制及其影响, 并指出环境因素对它们所产生的影响; 最后, 对当前研究存在的不足及该领域未来的研究方向进行总结和展望。希望以此增强人们对性选择和性冲突理论的认识, 促进其在植物繁殖生态学中的运用与发展。     

Gamete attachment process revealed in flowering plant fertilization

Sex-possessing organisms perform sexual reproduction, in which gametes from different sexes fuse to produce offspring. In most eukaryotes, one or both sex gametes are motile, and gametes actively approach each other to fuse. However, in flowering plants, the gametes of both sexes lack motility. Two sperm cells (male gametes) that are contained in a pollen grain are recessively delivered via pollen tube elongation. After the pollen tube bursts, sperm cells are released toward the egg and central cells (female gametes) within an ovule (Fig. 1). The precise mechanism of sperm cell movement after the pollen tube bursts remains unknown. Ultimately, one sperm cell fuses with the egg cell and the other one fuses with the central cell, producing an embryo and an endosperm, respectively. Fertilization in which 2 sets of gamete fusion events occur, called double fertilization, has been known for over 100 y. The fact that each morphologically identical sperm cell precisely recognizes its fusion partner strongly suggests that an accurate gamete interaction system(s) exists in flowering plants.Open in a separate windowFigure 1.Illustration of the fertilization process in flowering plants. First, each pollen tube accesses an ovule containing egg and central cells. Next, the 2 sperm cells face the female gametes in the ovule after the pollen tube bursts. Finally, each sperm cell simultaneously fuses with either egg or central cell.     

青藏高原及周边高山地区的植物繁殖生态学研究进展

青藏高原及周边高山地区孕育了极为丰富的植物多样性资源, 研究该地区植物如何顺利完成繁殖过程有助于我们理解植物对典型高山环境的进化和适应机制。该文综述了青藏高原地区高山植物在资源分配、繁殖方式、花部特征演化等方面的研究进展, 包括全球气候变化对植物繁殖特征的影响, 以及一些新技术和新方法在本研究领域的应用。在高山地区限制性环境中, 随海拔升高, 繁殖分配通常表现出增大的趋势, 其中投入到雄性资源的比例上升, 但具体的资源分配模式还要取决于植株的交配系统、个体大小、生活史特征、遗传特性以及环境中的资源有效性等。面对资源和传粉的双重限制, 植物在不同繁殖方式之间存在权衡, 当传粉者稀少时, 克隆繁殖和自交有利于繁殖保障; 而有性繁殖和异交能够提高种子的质量和后代的遗传多样性, 从而在复杂多变的气候条件下有利于种群的维持。因此, 不同繁殖方式的结合以及泛化的传粉互作网络可能是应对高山限制性环境的最优选择。花部特征的演化主要受到当地传粉者的选择压力, 但是外来传粉者、植食者、盗蜜者以及非生物环境(如温度、雨水和紫外辐射等)对花部性状的影响越来越受到重视。近年来, 青藏高原因其脆弱性和对气候变化的高度敏感性而在全球气候变化研究中备受关注, 以全球变暖和氮沉降增加为显著特征的全球气候变化正在直接或间接地影响着该地区高山植物的繁殖特征。气候变化影响植物和传粉者的物候并引起物种的迁移, 最终将导致植物与传粉者的时空不匹配。植物通过改变花部特征(花展示、花冠结构、花报酬的数量和质量)来响应气候变化, 这可能会改变其传粉者的类型、数量和访花行为, 从而最终影响植物的繁殖成功。3D打印和高通量测序等新技术和新方法的应用有助于促进植物繁殖生态学研究的进一步发展。3D打印的花能够精确控制其形态构造, 可以用于研究精细的花部特征变化对于传粉者行为的影响, 在此基础上与人工饲养的传粉者结合使用, 有助于进一步研究传粉者介导的花部特征演化。随着高通量测序技术的发展, 植物繁殖生态学领域, 尤其是花部特征演化的许多重要问题的潜在机制得以深入研究。该文最后提出了目前研究中需要注意的问题以及值得深入研究的发展方向。     

苔藓植物生殖生态学研究

近年来苔藓植物生殖生态学研究主要集中于繁育系统、生殖代价与对策,以及不同生殖方式对种群遗传变异的影响等方面。生殖结构的原始性及其对水分的独特需求,以及雌雄异株比例较高等导致苔藓植物中有性生殖比例偏低;雌配子体很少完成整个有性生殖过程,其“真实的生殖代价”主要指雌性性表达(雌配子发生)的能耗,并且显著低于雄性性表达;基于对资源有效分配的生殖对策而导致雌性偏向及部分孢子体败育。无性生殖有利于不同生境条件下有效种群的发展与维持,其多样化的繁殖方式导致复杂的种群动态。苔藓植物具有较高的种群遗传多样性,生殖方式与种群遗传变异无直接因果关系,孢子与无性繁殖体不同的散布能力对于种群间遗传分化具有一定的影响。     

Reproductive ecology of Naididae (Oligochaeta)

Asexual reproduction is employed by species of Naididae during favorable environmental conditions. In species characteristic of aquatic habitats subject to rapid fluctuations in water levels and temperatures most individuals in a population become sexually mature, and there is degeneration of the alimentary tract, a shortened breeding season, and aclitellar formation of cocoons. Cocoon deposition allows a population to survive periods of environmental stress. Sexual reproduction predominates near the edges of ranges where stress conditions are more prevalent. Species that reproduce sexually in spring are intolerant of summer conditions, while those that breed in autumn are intolerant of winter. Species typical of environmentally stable bodies of water usually have a minority of the population mature at any time, an extended breeding season, and the ability to continue feeding while mature; thus, adaptations for survival in unstable habitats are lacking.     

The evolution of the life cycle of brown seaweeds

The brown seaweeds (Phaeophyta) are well-suited for testing theories of the evolution of the sexual alternation of haploid and diploid generations because of the great diversity of life cycles within the phylum. Three theories are investigated in this paper. (1) Diploid growth evolves because it has the effect of complementing deleterious recessive mutations. This is rejected because (a) ancestral haplonty is not a parsimonious inference from current phylogenies; (b) the exaggeration of diploid growth does not evolve in a comb-like fashion; (c) forms with predominantly haploid growth have evolved from smaller isomorphic ancestors; and (d) there is no correlation between haploid growth and monoecy. (2) Diploid growth evolves when gamete dimorphism leads to intense sexual selection, favouring the production of genetically diverse gametes through meiosis. This is rejected because diere is no correlation between the dominance of the diploid generation and the degree of gamete dimorphism. It is possible to show that gamete dimorphism itself has evolved in the Phaeophyta through the increase in size of the macrogamete in forms that have evolved larger sporophytes. (3) Microthalli become specialized as gametophytes because fusion is promoted by releasing gametes into the boundary layer; macrothalli become specialized as sporophytes because dispersal is promoted by releasing zoospores into the water column. This is consistent with the sexual and reproductive biology of Phaeophyta. The classic sexual cycle can then be interpreted as evolving from an asexual alternation of microthallus and macrothallus, governed largely by environmental factors, through selection for the appropriate association of ploidy with vegetative size. The exceptions to this general rule are forms in which gametes are released from macrothalli, where a different suite of sexual characters has evolved.     

Asexual and sexual reproductive strategies in clonal plants

Most plants can reproduce both sexually and asexually (or vegetatively), and the balance between the two reproductive modes may vary widely between and within species. Extensive clonal growth may affect the evolution of life history traits in many ways. First, in some clonal species, sexual reproduction and sex ratio vary largely among populations. Variation in sexual reproduction may strongly affect plant’s adaptation to local environments and the evolution of the geographic range. Second, clonal growth can increase floral display, and thus pollinator attraction, while it may impose serious constraints and evolutionary challenges on plants through geitonogamy that may strongly influence pollen dispersal. Geitonogamous pollination can bring a cost to plant fitness through both female and male functions. Some co-evolutionary interactions, therefore, may exist between the spatial structure and the mating behavior of clonal plants. Finally, a trade-off may exist between sexual reproduction and clonal growth. Resource allocation to the two reproductive modes may depend on environmental conditions, competitive dominance, life span, and genetic factors. If different reproductive modes represent adaptive strategies for plants in different environments, we expect that most of the resources should be allocated to sexual reproduction in habitats with fluctuating environmental conditions and strong competition, while clonal growth should be dominant in stable habitats. Yet we know little about the consequence of natural selection on the two reproductive modes and factors which control the balance of the two reproductive modes. Future studies should investigate the reproductive strategies of clonal plants simultaneously from both sexual and asexual perspectives. Translated from Acta Phytoecologica Sinica, 2006, 20(1): 174–183 [译自: 植物生态学报]     

Asexual and sexual reproductive strategies in clonal plants

Most plants can reproduce both sexually and asexually (or vegetatively),and the balance between the two reproductive modes may vary widely between and within species.Extensive clonal growth may affect the evolution of life history traits in many ways.First,in some clonal species,sexual reproduction and sex ratio vary largely among populations.Variation in sexual reproduction may strongly affect plant's adaptation to local environments and the evolution of the geographic range.Second,clonal growth can increase floral display,and thus pollinator attraction,while it may impose serious constraints and evolutionary challenges on plants through geitonogamy that may strongly influence pollen dispersal.Geitonogamous pollination can bring a cost to plant fitness through both female and male functions.Some co-evolutionary interactions,therefore,may exist between the spatial structure and the mating behavior of clonal plants.Finally,a trade-off may exist between sexual reproduction and clonal growth.Resource allocation to the two reproductive modes may depend on environmental conditions,competitive dominance,life span,and genetic factors.If different reproductive modes represent adaptive strategies for plants in different environments,we expect that most of the resources should be allocated to sexual reproduction in habitats with fluctuating environmental conditions and strong competition,while clonal growth should be dominant in stable habitats.Yet we know little about the consequence of natural selection on the two reproductive modes and factors which control the balance of the two reproductive modes.Future studies should investigate the reproductive strategies of clonal plants simultaneously from both sexual and asexual perspectives.     

Distribution of ceramidephosphoinositol in red seaweeds

An inositol-containing sphingophospholipid ceramidephosphoinositol (CPI) found for the first time in red macrophytic algae proved to be typical of the Rhodophyta. The CPI content varied among the algal species from trace amounts to 15.7% of the total phospholipids and depended on season. Red seaweeds provide a more convenient source of ceramidephosphoinositol than other organisms.     

How do sexual expression,reproductive phenology and reproductive success relate to sexual systems in Fissidens Hedw. (Fissidentaceae)? A case study comparing two different sexual systems in mosses

• Reproductive performance is known to differ between co‐sexual and non‐co‐sexual species. Thus, our aim was to determine whether: (i) the distance between sex structures is negatively associated with sex expression; (ii) male gametangia take longer to mature in rhizautoicous species than in gonioautoicous species; and (iii) the gonioautoicous sexual system has greater reproductive success (i.e. percentage of ramets with sporophyte) than the rhizautoicous sexual system.
• One population each of the mosses Fissidens scariosus and F. submarginatus, rhizautoicous and gonioautoicous, respectively, in a remnant of Atlantic Forest in Brazil were sampled monthly from September 2016 until August 2017. The number and phenophases of antheridia, archegonia and sporophytes were analysed for each species. Sexual expression and reproductive success were calculated, and reproductive phenology compared across environmental variables.
• As expected, sexual expression was significantly higher for the gonioautoicous species, which produced antheridia throughout the year and archegonia over many months, while gametangia production by the rhizautoicous species occurred only during the rainy season. Mean number of gametangia per perigonium and perichaetium were slightly higher for the rhizautoicous species (6.84 antheridia; 11.38 archegonia) than for the gonioautoicous species (4.39; 7.62). Gametangia and sporophyte production in the rhizautoicous species were markedly seasonal compared to that of the gonioautoicous species, although reproductive success did not differ.
• Therefore, we infer that the rhizautoicy (i.e. a functional dioicy) promotes lower expression of gametangia compared to gonioautoicy but is more efficient and so obtains the same reproductive success.