桑树的遗传变异特点及在品种选育中的应用

Characteristics of Heredity and Variation in Mulberry and Their Application in Selection and Breeding of Varieties

我国具有悠久的桑树栽培历史,拥有3 000余份桑树种质资源,分属15个桑种和4个变种,并逐渐形成适应不同生长环境的8个生态类型。依据已有的研究结果,综述桑树遗传变异的特点包括:广泛分布、自然有性杂交和异花授粉以及缺乏稳定性选择等,促进了桑树的突变发生,形成遗传变异的多样性;无性繁殖方式产生了丰富的无性系变异;性状遗传值中非加性效应占有较大比例;无性系品种间杂种一代存在复杂的多样性分离和经济性状的普遍退化;存在丰富的多倍体系列和普遍的混倍现象等。对桑树品种选育研究提出建议:基于桑树的高度杂合习性,不仅要重视研究不同品种中加性效应在遗传值中所占比率,更要研究非加性效应所占比率及充分利用的方法;基于桑树遗传变异的多样性和丰富的无性系变异,加强无性系和田间选优育种;利用桑树混倍现象,将培育多倍体特别是三倍体品种作为一条有效的多倍体育种途径。

Mulberry cultivation has a long history in China.Until now,more than 3 000 genetic resources have been collected,which belong to 15 mulberry species and 4 variants.Besides,they have gradually formed 8 ecological types adaptable to various growth environments.Based on existing research results,this article summarized the characteristics of genetics and variation of mulberry including： wide distribution,natural sexual hybridization,heterogeneous pollination and lack of multigenerational successive selection that promoted mutation in mulberry to generate diversity of heredity and variation;asexual reproduction that generated rich variations in vegetative lines;non-additive effects that contributed a comparatively large portion to genetic values of characters;F1 generation between two asexual varieties that showed a large degree of diversity segregation and a general degeneration of economic characters;and the existence of abundant polyploidy series and widespread mixoploidy lines.The suggestion of the research on selection and breeding of mulberry varieties are given.Based on high heterozygosity of mulberry,great attention should be paid to study not only the contribution rates of additive effects of different varieties to genetic values but also those of the non-additive effects and ways to utilize them.Based on the rich diversity of mulberry heredity and variation and abundant variations of mulberry asexual lines,selecting superior plants among asexual lines in the field should be strengthened.And the utilization of mulberry mixoploidy is an effective way to breed polyploidy varieties,especially the triploid ones.