32种杜鹃花属植物在迁地保育条件下的自交研究

Self-fertilization of 32 Rhododendron species under ex situ conservation

关键词:  迁地保育, 自交, 可育性, 杜鹃花属

Key words:   ex-situ conservation, self-fertilization, fertility, Rhododendron

摘要:

迁地保育条件下的杜鹃花属植物自交可育性一直缺乏系统的比较研究,该文对5亚属13亚组32种杜鹃花属植物的自交进行了数据采集与分析,初步揭示了迁地保育条件下杜鹃花属植物自交育性特征。结果表明:(1)自交可育与不育是杜鹃花属植物有性生殖中的两个并存现象, 自交能育型种类或多于不育型。在受试的32种杜鹃花中, 自交不育型10种、弱可育型5种、可育型7种、高可育型10种, 其中27种的自交育性为首次报道, 涵盖包括杜鹃亚属杜鹃组(sect. Rhododendron)和马银花亚属(subgen. Azaleastrum)及常绿杜鹃亚属(subgen. Hymenanthes)中银叶杜鹃亚组(subsect. Argyrophylla)等5个亚组在内的未被研究的类群。(2)通过与自然授粉有关育性指标的比较, 发现不同种类的自交可育性指标有大幅度降低及增高这两类截然不同的现象, 从而提出了自交可能是部分杜鹃花属植物的适应策略, 或者对不利环境及其媒介条件的主动响应。(3)在云锦杜鹃亚组(subsect. Fortunea)这个被认为最原始的杜鹃花类群中, 具备从自交不育到高可育的所有类型, 并可能由此奠定整个杜鹃花属的遗传基础, 而类群与种类分布的不同区域气候环境长期直接的或通过影响传粉媒介间接的作用,则可能是最终塑造该属植物自交育性多样化的外部动力。(4)该文还依据有关自交的研究结果,对杜鹃花属植物的迁地保育、育种、相关学科发展进行了讨论,并认为后合子期败育的理论不能完美地解释自交不能坐果的现象, 而多倍体似不会导致自交不育。

Abstract:

The self-fertility of Rhododendron under the ex-situ conservation conditions remains largely unclear due to the lacking of comparative study among the species in the genus. In this study, self-bred experiments on 32 species including 13 subsectiosns within 5 subgenera were carried out for a period of four years of data collection and analysis in the main bases of Longchi Dujiangyan(1 700 m above sea level), Yutang Dujiangyan(700 m), and Emeishan Biological Test Station(805 m). Using the green seedling rate(Gs)as the main index and green seedling coefficient(Gc), rate of capsul set(St)and unit number of fertility seed(Sf)as the auxiliary indexes, the experiment revealed the self-fertility characteristics of Rhododendron. The results were as follows:(1)Self fertility and sterility is two coexisting phenomena of Rhododendron sexual reproduction, and the former had more types than the latter. Of the 32 Rhododendron species, ten species were self-sterility, five species weak fertile type, seven species fertile type, and ten species high fertility type. Twenty-seven self-fertility species from sect. Rhododendron, subgen. Azaleastrum and subsect. Argyrophylla, the other four subsections in subgen. Hymenanthes and other groups were reported for the first time in China.(2)Through the comparison with natural pollination related fertility index, there were two distinct reflection found in fertility index of different species in inbred background: greatly reduced or increased, thus putting forward self fertility is an adaptation strategy for partial species of Rhododendron, or active in response to adverse environmental conditions.(3)Subsect. Fortunea considered as the most primitive taxa, with all types from self sterile to high fertility, may laid inherent genetic basis for the genus, and different regional climateand environment for the specific groups and species, through the long-term direct or indirect effects on pollinator, may be an external force that shape the diversification on self fertility of the genus ultimately.(4)The conservation, breeding and development of related disciplines were also discussed on the basis of the research results, the mechanism about post-zygotic abortion could not explain perfectly capsul aborted for some species and the polyploidy might not lead to self sterility in the genus.