杜鹃花属植物杂交不亲和与败育分布研究

Distribution of hybrid incompatibility and sterility of Rhododendron

关键词:  杜鹃花属, 杂交, 不亲和, 败育, 杂种不活, 可交配性

Key words:  Rhododendron, cross, incompatibility, sterility, hybrid inviability, crossability

摘要:

该研究以杜鹃花属5亚属3组17亚组38种, 计109个不育组合及91个可育组合的杂交结果为依据, 对4个杂交不亲和指标与败育系数及败育频度参数进行了分析。结果表明:(1)杜鹃花属不同类群间杂交的不育组合比例约为54.5%, 其不亲和与败育包括不能坐果(capsul aborted,Cab型)、坐果但不能形成种子(seed aborted,Sab型)和能形成种子但不能发芽(seed not germinated, Sng型)3种情况, 其中Cab与Sab类型均可能是前合子期不亲和与后合子期不亲和的复合表征, Sng型则可以肯定为后合子期种子发育阶段败育的情况, Cab:Sab:Sng=81:13:15; 而可育组合中部分败育苗无疑属于“杂种不活hybrid inviability”的败育类型。(2)有关不育类型的分布与杜鹃花属植物亲本类群及其分类与亲缘关系具有明显关联, 从同一亚组内、同一亚属内到不同亚属间杂交的不育类型的分布呈Sng型→Sab型→Cab型增加的趋势, 杂交双亲分类上亲缘关系越密切Sng型的频度越高, 反之关系越疏远Cab型的频率越高, 亚属间远交往往止于Cab型。(3)“杂种不活”为败育苗的表现形式之一, 从同一亚组、同一亚属到不同亚属间杂交, 其败育等级频度分布通常也从无或轻度败育到严重败育方向发展,常绿杜鹃亚属内杂交的败育情况明显低于杜鹃亚属内杂交, 这与后者多倍体亲本的介入相关, 而上述2亚属间杂交的苗木败育则更加严重, 但映山红(R. simsii)分别与百合花杜鹃(R. liliiflorum)和毛肋杜鹃(R. augustinii)的亚属间杂交未出现败育苗分布。

Abstract:

Four hybridization incompatibility index and sterility coefficient(IGc)and frequency(Fstl )were analyzed, based on 109 sterility and 91 fertility combinations involving 38 Rhododendron species which belong to five subgenera, three sections, seventeen subsections. The results were as follow:(1)The sterile rate of Rhododendron inter-species cross was 54.5%, which included three types(Cab-capsul aborted, Sab-seed aborted and Sng-seed not germinated), and both of Cab and Sab types may have a composite characterization of pre-zygotic incompatibility and post-zygotic sterility, and Sng type can be sure to post-zygotic sterility of “hybrid inviability” in seed developmental stage, Cab:Sab:Sng=81:13:15.(2)The types of sterile distribution appeared the parental relationship and its classification had obvious correlation, from within the same subsection to the same subgenus to different subgenus, the distribution types of hybrid sterility showed a trend increase Sng→Sab→Cab, the denser in taxonomic relationships from the parents, the higher of frequency in Sng type and on the contrary, the more distant in the relationship, the higher of frequency in Cab type, so the outcrossing of inter-subgenera often stop in Cab type.(3)“Hybrid inviability” is one of the forms of expression as the hybrid seedling sterility, from the same subsection to the same subgenus to different subgenra, the seedling dying rank of frequency distribution usually showed no or mild defeated to serious defeat in development direction; the seedling sterility of intra-subgen. Hymenanthes was significantly lower than that of intra-subgen. Rhododendron, with the latter polyploid parents involved in, and the hybrid seedling sterility was more serious in inter-subgenera on the above two subgenera, but without seedling sterility in the two hybrid combinations of inter-subgenera, R. simsii × R. liliiflorum and R. augustinii respectively.