Study On Correlation Between Molecular Genetic Distances Of Parents And Heterosis In Indica Rice

The molecular marker assisted breeding is an efficient way for making full use of genetic diversity, fine seletion at molecular level, which leads develop rice hybrids for rice production and peaple's demands. In this research, genetic distances between 7 male sterile lines and 110 restorer lines were analysed by SSR Markers. Acorrding to the analysis data of genetic distances, the 168 crosse combinations were maded by use the NCâ…¡design. Teyou 63 that is a most hybrid indica rice was used as the control variety. Agronomic and economic characters closely related to yield were recorded and analysed for the relationships with yields.The relationship between molecular genetic distances and heteorsis was further investigated to know whether the heterosis could prodict through the molecular genetic distances between parents. The results were as follows:1. A total of 36 allelic differentiations were detect by 11 primers in the PCR analysis with 2-4 and mean value 3.26 alleles detected per locus. The genetic distance between the restorer lines and sterile lines varied from 0.0606 to 0.6364 and was 0.3562 in average. Cluster analysis based on the genetic distances indicated that all of the materials could be divided into three groups with all the male sterile lines gathered in a independent group separated from restorers. So it was showed that the genetic differences among indica parents could be learly anapysis by SSR markers2. Among the components related to the yield of hybrids, panicle number per plants was major factor contributing to yield, followed by grain setting and panicle height. This explained that choosing parents for rice hybrid must be important to attach to the panicles per plant. However, the other characters can not neglected at the same time.3. The result of correlation analysis between the genetic distances of parents and heterosis showed that: (1) Significant correlations between F₁ yield per plant and parental genetic distance appeared in the the genetic distances ranging from 0.3000 to 0.4000, while in the other rangement, the correlation was not significant. (2) In most rangement the genetic distance between single male sterile line and restorers were not significantly correlated. However, in few scales, the F₁ yield per plant appeared negatively correlated with the heterobeltiosis of the hybrid combinations. (3) The correlation between genetic distance and heterobeltiosis of F₁ character existed considerable difference. These suggested that the SSR genetic distances could not be used to predict the yield and performance of heterosis, but part of traits relate to yield would be understood from the correlation.4. Yield of 11 hybrids showed significant higher than the control variety, Teyou 63, and three of them, XianA/Zhongda542, BoA/06T2351 and BoA/Zhongda552 with their parental genetic distances ranging from 0.24 to 0.3, yielded more than 10% higher than the control. Analysis of parental genetic differences in the super heterotic combinations showed, the yields increase didnot follow the genetic distances increase, but the genetic distances of these super heterotic hybrids were in a range from 0.24 to 0.3, which could provide a valuable reference to the selection of parents in hybrid rice breeding.