Analysis On Associated Markers To CMS Restoring And Grain Dimension Using Zhong413 Introgressive Line (IL) Population In Rice

Cytoplasmic male sterility (CMS) and grain dimension are two important traits of rice improving. We used 130 rice cultivars as the donor parents and a CMS restorer "Zhong 413" as the recurrent parent (RP), to build a set of multi-parent introgressive line (IL) population by 2-4 times of backcrosses and more than 2 times of selfing. Test hybrid populations were developed by making crosses between CMS lines "Yu A", "Chuanxiang 29 A" and the introgression lines. The associated markers for CMS and grain dimension were analyzed as shown below:1. Grain length and width were measure for the lines with longer grains from total 2500 ILs, selected by optimal observation. There were 667 ILs with grain length more than 7.0mm, a mean value of 8.4mm and maximum value of 10.6mm. The grain width (GW) varied from 2.0mm to 3.8mm. The grain length/width ratio (LWR) varied from 2.3 to 4.3. These lines are noticeably different in the grain dimension from the RP.2. Based on the molecular linkage maps published by Cornell University, a total of 480 SSR and 40 InDel markers were selected to detect the population and search the associated markers. We use a two-step procedure to filtrate the significant markers for the traits. Firstly, we use a few extreme lines to scan whole genome to find the significant markers by the Chi-square test; then more lines with significant changes from the RP were used to confirm. The association between markers and the traits were build up based on the Chi-square test.3. Several chromosomal segments were more frequently introduced from the donors in the lines with sterile or low fertile test hybrids, including RM576-RM490 -RM575 on Chr. 1, RM258-RM6704-RM1937 on Chr. 10 and RM206-RM254 -RM1233-RM7654 on Chr. 11, suggesting the substitution of Zhong413's restore genes in these chromosomal regions. It was also observed that introgression of some other alleles of these markers can result in more high seed setting in test hybrid than the RP.4. In the lines with grain weight significantly higher than the RP, there were much higher introgression frequency in several chromosomal regions than the theoretical expectation, including RM347-RM520 on Chr. 3, RM269-RM294A -RM484 -RM333 on Chr. 10, and RM206-RM144 on Chr. 11.