杜鹃花属植物种间杂交向性研究

Direction of inter-specific cross of Rhododendron

关键词:  杂交向性, 正反交, 亲和性, 不育性, 杜鹃花属

Key words:  hybrid direction, reciprocal cross, compatibility, sterility, Rhododendron

摘要:

为探讨杜鹃花属植物种间杂交的向性特征, 依据该属5亚属、3组、12亚组、32种、33对正反交组合与自交性质清楚的186个杂交组合, 对有关向性问题进行了初步研究。结果表明:(1)杜鹃花属植物种间杂交由双向可育→单向不育→双向不育的比率变化与其亲本的系统位置由原始→进化以及双亲间的亲缘关系由密切→疏远同向; 原始的常绿杜鹃亚属(Subgen. Hymenanthes)内种间比较进化的杜鹃亚属(Subgen. Rhododendron)内易于杂交, 而该两亚属之间却存在密切的亲缘关系, 因此其亚属间杂交的可育比率也高于其他亚属间杂交。(2)在进化维度上, 该属植物的种间杂交单向不育通常无固定的亲本搭配方向, 但常绿杜鹃亚属内(Intra-Subgen. Hymenanthes, Intra-HY)、杜鹃亚属内(Intra-Subgen. Rhododendron, Intra-RH)和映山红亚属 × 羊踯躅亚属(Subgen. Tsutsus × Subgen. Pentanthera)间的杂交搭配, 有一定的倾向性。(3)种间杂交可育性与自交特性不同的亲本搭配方式相关, 可育性大小的总倾向是SC × SC>SI × SC≥SC × SI>SI × SI, 其生殖进化方向是从自交亲和(SC)到自交不亲和(SI), 并伴随异交生殖隔离的加强。(4)细胞不育和多倍体是引起单向不育的两个重要原因,SI亲本的介入会大幅度地增加种间杂交的不育比率。

Abstract:

In order to discuss the direction feature of inter-specific cross of Rhododendron, the direction feature about the genus was studied based on the cross combinations of 33 reciprocal pairs and 186 combinations of selfing nature to be clear, involving five subgenera, three sections, twelve subsections and 32 species of Rhododendron. The results were as follows:(1)In inter-specific cross of Rhododendron, there was the same direction of number rate change from bidirectional fertility to unidirectional sterility to bidirectional sterility with the parent alliance from origin→advance and the relationship from closeness to alienation; The inter-specific cross appeared more easily in Intra-Subgen. Hymenanthes as the primitive group than in Intra-Subgen. Rhododendron as the more advance group, and as both of the above two subge-nera had more relationship in evolution, the fertility rate of Subgen. Hymenanthes × Subgen. Rhododendron appeared higher than that of the other inter-subgeneric cross.(2)In the evolutionary dimension, the unidirectional sterility in inter-specific hybrid of the genus usually had no obvious fixed direction of parent collocation, but in Intra-Subgen. Hymenanthes(Intra-HY), Intra-Subgen. Rhododendron and Subgen. Tsutsus × Subgen. Pentanthera, the collocation had a certain tendency.(3)The fertility of inter-specific cross had obvious relevance with parental self-character, the total tendency of fertility size showed SC × SC>SI × SC≥SC × SI>SI × SI, the general direction of the reproductive behavior evolution of Rhododendron was from self-compatibility(SC)to self-incompatibility(SI)and accompany with increase of outcrossing reproductive isolation.(4)Cytoplasmic sterility and polyploid intervention were two important causes that resulted in unidirectional incompatibility or sterility, and SI increased the rate of the hybrid sterility drastically.