32种杜鹃花属植物亚属间杂交的可育性研究

Cross fertility of inter-subgen. Rhododendron of 32 Rhododendron species

关键词:  可交配性, 单向不亲和,杂种败育, 远缘杂交, 亚属间杂交, 杜鹃花属

Key words:  crossability, unilateral incompatibility, hybrid sterility, distant hybridization, inter-subgenus cross, Rhododendron

摘要:

为探索杜鹃花属植物亚属间杂交的可育性规律, 该文对常绿杜鹃亚属(subgen. Hymenanthes)、杜鹃亚属(subgen. Rhododendron)及马银花亚属(subgen. Azaleastrum)、映山红亚属(subgen. Tsutsusi)和羊踯躅亚属(subgen. Pentanthera)的亚属间杂交进行了研究, 共涉及杜鹃花属植物5亚属15亚组32种, 杂交组合118个。结果表明:(1)杜鹃花属植物的亚属间杂交存在明显的生殖障碍, 其可育性水平与亚属及其类群组合有关, 高、中、低与不育比例为2:16:8:92, 可育比例仅20.0%, 杜鹃亚属与马银花亚属等4个亚属级组合杂交未显现可育性。(2)亲本杂交组合方式对亚属间杂交有不同程度的影响,一些类群组合有明显的向性。以杜鹃亚属做母本与常绿杜鹃亚属的云锦杜鹃亚组杂交的可育组合比高于反交, 且在有关大王杜鹃、粘毛杜鹃、露珠杜鹃和马缨花的杂交中也是如此, 但与银叶杜鹃亚组杂交正好相反; 另外,12对单向可育组合, 分布于常绿杜鹃亚属与杜鹃亚属等4类亚属级杂交组合中。(3)杜鹃花属的亚属间杂交不亲和与败育现象明显, 不可育组合百分率占80%, 不能坐果是败育的主要表征, 所有可育组合的绿苗率比值和单位种子数比值无一例达到相应母本的自然授粉水平。(4)双亲系统分类上的关系对亚属间可交配性具有重要影响并与可育程度一致, 染色体倍性也有一定的作用。(5)有关研究为探索和认识杜鹃花属植物亚属间进化遗传联系提供了新的证据和思考, 银叶杜鹃亚组可能是解释常绿杜鹃亚属与杜鹃亚属进化遗传联系的重要类群, 杜鹃亚属的多鳞杜鹃可能与常绿杜鹃亚属具有广泛的血亲关系, 其中多鳞杜鹃与岷江杜鹃彼此为生态相邻种并有可能在长期的演化过程中有遗传渗透, 百合花杜鹃和毛肋杜鹃分别与映山红亚属、腺果杜鹃与马银花亚属, 越峰杜鹃和繁花杜鹃分别与映山红亚属, 大白杜鹃与羊踯躅亚属间的联系均需要深入研究。

Abstract:

In order to study the fertile law of the cross ofinter-subgenera of Rhododendron, we studied the inter-subgenus cross of subgen. Hymenanthes, subgen. Rhododendron, subgen. Azaleastrum, subgen. Tsutsusi and subgen. Pentanthera. The test involved a total of 32 species and 118 hybrid combinations. The results were as follows:(1)The inter-subgenus cross of Rhododendron was hard and the fertile level was related to the combination between the subgenera andtheirgroupes,and higher, middle and lower and non fertile ratios were 2:16:8:92, the total fertile combinations was 20%, and the cross four combinations of iner-subgegera did not show fertility between subgen. Rhododendron and subgen. Azaleastrum and the like.(2)The parant combination effected the inter-subgegus cross in different extents and some combinations had a direction. There was higher fertility as female parent of subgen. Rhododendron than as father parent in the cross combination of subgen. Rhododendron and subsect. Fortunea of subgen. Hymenanthes, and that showed the same in subgen. Rhododendron with R. rex, R. glischrum, R. irroratum, R. delavayi respectively, but with subsect. Argyrophylla, and twelve pairs of unilateral fertile combinations distributed in four types of inter-subgenus combinations such as subgen. Hymenanthes and subgen. Rhododendron.(3)Incompatibility or sterility of inter-specific hybridizationin the inter-subgenerus was very serious and the nonfertile combinations occupied 80%, mainly present as nonfruit setting, and in all of the fertile combinations, the ratios of green seedling rate and unit number of fertile seed were lower than the natural pollination as female parent.(4)Relationship between subgenerus in plant systematics had an important influence in mating fertility and correlated the fertile extent, and meanwhile polyploid also carried weight.(5)That provided some now evidence and way of thinking for exploring and finding out the relationship of evolution and heritance in inter-subgenerus of Rhododendron, and subsect. Argyrophylla may be an important group in explaining the evolution relationship between subgen. Hymenanthes and subgen. Rhododendron, and R. polylepis of subgen. Rhododendron can own a wide relationship with subgen. Hymenanthes and we can not exclude a possibility of genetic introgression between this species and R. hunnewellianum as neighbor in nature; and the relationship of some combinations need to be studied in depth for example, R. liliiflorum or R. augustinii(subgen. Rhododendron)and subgen. Tsutsusi, R. davidi(subgen. Hymenanthes)and subgen. Azaleastrum, R. yuefengense or R. floribundum(subgen. Hymenanthes)and subgen. Tsutsusi,R. decorum(subgen. Hymenanthes)and subgen. Pentanthera etc