种子老化对玉米种质资源遗传完整性变化的影响

对经老化处理得到的不同发芽率水平的玉米地方品种条花糯进行农艺性状观察和SSR分子标记分析.结果表明,种子发芽率水平下降影响出苗植株中芽鞘和叶鞘颜色的比率.当发芽率降到32%时,浅紫色芽鞘植株的比率降至0.当发芽率下降时,浅紫色叶鞘植株的比率升高,而白色叶鞘植株的比率则下降.经SSR分析发现,低发芽率群体的多态性条带百分率、等位基因数、有效等位基因数、基因多样性指数、Shannon指数等遗传参数,与对照群体的遗传参数相比都有所下降,表明老化处理后群体内的遗传多样性低于对照群体的遗传多样性,群体内遗传变异出现下降.本试验结果表明,植株形态标记和SSR分子标记可以作为老化种子遗传完整性变化的检测方法,同时认为对于异质种质资源材料,低的发芽率更新标准不利于种质资源遗传完整性的保持.

Effect of Seed Aging on Changes of Genetic Integrity in Maize Germplasm

Genetic alterations of maize landrace cv. Tiaohuanuo populations having different germination levels were analyzed using agronomic traits and SSR markers. It showed that the proportion of plant with different coleoptile and leaf sheath colours varied with the decline of germination percentage. When seed germination percentage declined to 32%, there was no light-purple coleoptile plant. On the other hand, the proportion of light-purple leaf sheath plant increased while the white leaf sheath plant decreased when seed germination percentage declined. The percentage of polymorphic bands, the number of alleles (na), effective number of alleles(ne), Nei's gene diversity index(h)and Shannon's information index(I) were lower in artificially aged population with lower germination percentage than in CK population with higher germination percentage using SSR. This indicated that the genetic diversity was lower in aged populations than in CK population. The result also showed that a low germination percentage standard for regeneration is disadvantageous for maintaining the genetic integrity of heterogeneous germplasm.