Four types of mating offspring (ie. intra-species cross, inter-species cross, selling, and backcross) were used as experimental populations to evaluate the extent of inbreeding depression in Liriodendron. And their phenotypic traits were compared, including seed plumpness, seed germination rate, and seedling growth, as well as their genotypic feature (the percentage of homozygous SSR loci). Results showed that seed plumpness and seed germination rate exhibited the same trends, that is, the seed plumpness and seed germination rate of intra-species cross was the highest, followed by inter-species cross, backcross and selfing. The seedling growth of inter-species cross was the highest, followed by backcross, intra-species cross, and selfing. The percentage of homozygote of selfing was the highest, followed by intra-species cross, back-cross and inter-species cross. All these indicate an evident inbreeding depression occurred in Liriodendron. Meanwhile, it is found that the SSR heterozygosity of L tulipifera is higher than that of L. chinense.%异交物种易发生近交衰退.为了研究濒危树种鹅掌楸天然种群的濒危机制,以鹅掌楸属树种4种人工交配类型(种间杂交、种内杂交、回交、自交)子代为材料,从表型(种子饱满度、出苗率、苗期生长量)和基因型(SSR位点)两方面分析了鹅掌楸近交衰退状况.结果表明:子代饱满度、出苗率有相同的变异趋势,种内杂交＞种间杂交＞回交＞自交.子代苗期生长量为种间杂交＞回交＞种内杂交＞自交.子代纯合子比率为自交＞种内杂交＞回交＞种间杂交,表明鹅掌楸属树种近交衰退明显.同时还发现北美鹅掌楸基因杂合度高于鹅掌楸.
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