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杂种优势是自然界的一种普遍现象,但在杂交水稻育种实践中也时常发现杂种劣势现象,为了更好地阐明杂交育种理论和揭示品种本质有必要对杂种劣势的遗传机理进行更深层次的研究。本研究旨在通过两个韩国粳稻品种(Aranghyangchalbyeo和Sanghaehyangheolua)及其正反交后代(F1,F2)特性的比较,解析水稻杂种劣势的表型、类别及其遗传模式。形态学分析表明,正反交F1植株的劣势表现均明显、稳定且不受环境影响,主要农艺性状的中亲劣势值均为负值,其中F1的株高、分蘖数和结实率与亲本相比显著降低(P<0.01);F1劣势表现从发芽后第5d开始,地下部的劣势表现比地上部更为明显。细胞组织结构观察表明,分蘖盛期F1劣势植株叶片发育正常,而其根部气腔发育较亲本迟缓,从而阻碍了地上部与地下部的通气情况,因此也影响了整个植株的正常生长。遗传学分析发现,该劣势组合成熟期F2群体中正常与劣势植株呈现7:9的分离,结合分蘖盛期该F2群体株高的分离模式,推断该杂种劣势的表型是由两个互补的显性基因控制。该研究结果为揭示杂种劣势的多样性及分子遗传机制提供了新思路。
Heterosis is a common phenomenon in nature. However, heterosis phenomenon is often found in the practice of hybrid rice breeding. In order to clarify the theory of hybrid breeding and reveal the essence of hybrid, it is necessary to conduct a deeper study on the genetic mechanism of heterosis. The purpose of this study was to analyze the phenotypic, classification and genetic patterns of heterosis in rice by comparing the characteristics of two Korean japonica cultivars (Aranghyangchalbyeo and Sanghaehyangheolua) and their reciprocal crosses (F1 and F2). Morphological analysis showed that the F1 plants showed obvious inferiority, stable and not affected by the environment, and the mid-parent and inferior values of the main agronomic traits were all negative. The plant height, tiller number and seed setting rate of F1 were similar to those of the parents (P <0.01). The unfavorable performance of F1 started from the 5th day after germination, and the inferior performance of the underground part was more obvious than that of the aerial part. The observation of the cell structure shows that the leaves of F1 plants at the tillering stage have normal development and the development of the air cavity at the root is slower than that of the parent, which hinders the aeration of above and below ground and thus affects the normal growth of the whole plant. Genetics analysis showed that the segregation of normal and inferior plants in the F2 population at the inferior combination showed a 7: 9 segregation. Based on the segregation pattern of the plant population at the tillering stage, the phenotype of the heterosis was deduced from two complementary Dominant gene control. The results provide new ideas for revealing the diversity and molecular genetic mechanisms of heterosis.