10种杜鹃亚属植物种间杂交的可育性研究

Cross fertility of intra-subgen. Rhododendron of 10 Rhododendron species

关键词:  杜鹃亚属, 亚属内杂交, 多倍体, 不亲和, 败育, 杜鹃花属

Key words:  subgen. Rhododendron, intra-subgenus cross, polyploidy, incompatibility, sterility, Rhododendron

摘要:

为探索杜鹃花亚属内异种杂交的可育性及其规律, 对杜鹃亚属有鳞大花亚组(subsect. Maddenia)、三花杜鹃亚组(subsect. Triflora)、亮鳞杜鹃亚组(subsect. Heliolepida)及腋花杜鹃亚组(subsect. Scabrifolia)等4亚组10个杜鹃花种类的22个杂交组合(其中18个数据完整组合)的可育性进行了研究。结果表明:(1)所涉及的杜鹃亚属不同亚组间及三花杜鹃亚组内杂交均较困难, 在18个数据完整组合中高可育与可育组合比率明显偏低, 不育比率高(55.6%)。(2)在10个不可育或败育组合中, 不能坐果(Cab型)、不能结实(Sab型)和可结实而种子不能发芽(Sng型)的数量分布为6:1:3, 其不亲和或败育发生的阶段可能涵盖了从前合子期到后合子期的整个阶段。(3)亲本一方为多倍体组合的可育率(41.6%), 尤其是母本为多倍体时, 比二倍体组合的可育率(50.0%)低且无高可育组合出现, 部分印证了倍性是导致该亚属植物不同种类杂交不亲和、不育与育性下降的重要原因, 但不是唯一原因, 亚组间杂交的可育率(16.7%)明显低于亚组内(三花杜鹃亚组内,58.3%)。(4)与相应的母本自然授粉结果相比, 杂交明显导致多数可育组合绿苗率比率和单位可育种子数量比率的大幅度下降, 这是双亲遗传差异及多倍体亲本介入后所导致的杂交衰退hybrid weakness现象。(5)在多倍体作母本的情况下, 杂交单向不育或非对称遗传渗透现象明显。

Abstract:

In order to study the fertile law of the specific cross of intra-subgen Rhododendron, cross of intra-subgen. Rhododendron was studied, including four subsections of ten species in twenty-two hybridized combinations(eighteen combinations for integrated data)to relate subsect. Maddenia, subsect. Triflora, subsect. Heliolepida and subsect. Scabrifolia in the subgenus. The results were as follows:(1)In both of the related different subsections and within subsect. Triflora, inter-specific hybridization was rather difficulty, and high fertility and fertile combined ratio was low, on the other hand, non fertile ratio was high(55.6%)in the eighteen combinations for integrated data.(2)The rates of capsul aborted(Cab), seed aborted(Sab)and seed not germinated(Sng)were 6:1:3 in ten non fertile or abortion combinations which might cover all of the pre-zygotic and post-zygotic incompatibility at the same time.(3)The fertile combination rate of any polyploid part of parents(41.6%)was lower than one of diploid parents(50.0%)and non high fertile types, that verified partly any polyploid part of parents, especially polyploid female, was the result of different kinds of incompatibility, sterility and decline in the cross of intra-subgenus, however that was an important reason but not the only reason, the hybrid fertile rates between the subsections(16.7%)were significantly lower than in intra-subsection(subsect. Triflora, 58.3%).(4)The cross of intra-subgen. Rhododendron, compared with the natural pollination as female, led to Rgs and Rsc values in most fertile hybrid combination decreased greatly, that should also belong to hybrid weakness due to the genetic differences and polyploid intervention from parents.(5)The phenomenon of hybrid unilateral incompatibility and sterility or asymmetric genetic introgression was obvious under polyploid intervention used as the female parent.