玉米自交系不同株系间存在着微小的遗传差异,开放授粉生产的亲本种子明显提高了杂交制种的产量,但对于微小遗传差异对杂种优势的贡献幅度和对产量构成因素的影响报道较少。通过3个玉米自交系遗传差异不同的株系,自交3代后株系间产量及相互间杂交优势分析,结果表明,同一自交系在遗传上存在微小差异的株系,产量水平及其产量构成因素仍然存在一定差异；自交系初始遗传差异越大,后代株系间的产量差异越大；初始单株遗传差异较小2个玉米自交系昌7-2和郑58具有微小遗传差异株系间杂交组合的超中亲优势分别达到10.55%、4.77%,超高亲优势分别达到3.69%、3.94%。对杂交优势贡献主要来自行粒数,其次是千粒重；通过关联分析找出行粒数相关基因的SNP标记14个(-logp>4),千粒重相关基因的SNP标记3个(-logp>3)。在开放授粉的条件下,株系间微小遗传差异有利于提高亲本和杂交制种产量。该结果为制定自交系繁殖技术提供依据。
英文摘要:
There are tiny genetic differences among different strains of maize inbred lines. Open pollinated production of parental seed can obviously improve the yield of hybrid seed production, but the contribution of the tiny genetic differences to yield constitute factors and to heterosis among inbred lines has been reported less so far. Through analyzing the genetic differences and the yield in three maize inbred lines among different strains, the results showed that the yield was different for the sister strains of the same inbred line with the tiny genetic differences. The bigger the initial genetic difference of inbred lines before self-bred selection was, the higher the yield of the strains after S3 generation was. The mid-parent yield heterosis of the two maize inbred strains with a smaller initial individual genetic difference, chang 7-2 and zheng 58, were 10.55% and 4.77% respectively, while of which over-parent yield heterosis were 3.69% and 3.94% respectively. The yield heterosis mainly came from the row grains, secondly from1000-kernel weight. It was found that SNPs associated with row grains were 14 (-logp>4) and kernel weight were 3 (-logp>3) through the correlation analysis. Under the condition of open pollination, small genetic difference among the strains was benefit to improve the seed yield of inbred lines and hybrid seed. The above results provided a basis for the development of inbred breeding techniques.
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