[Analysis of photoperiod-sensitivity genes in Minghui63, an restorer line of indica rice(Oryza sativa L.)].

Hybrid rice is very important in agriculture production in China. Its selecting property makes it significant to study the genetic performance of F1's date to heading (DH). Minghui63, an indica rice restorer line, has been widdly applied to hybrid rice seed production in China, but the photoperiod-sensitivity gene of heading date in this restorer line is still unknown. This definitely limited the further use of this restorer line in breeding practice and re-production of hybrid seeds. To solve this problem, using heading time nearly isogenic lines EGO-EG7, ER-LR and two heading date QTL-isogenic lines, NIL (Hd1) and NIL (Hd4), with the genes of Nipponbare but Hd1 (Se-1) and Hd4 (E1) genes from Kasalath, respectively, we performed a genetic analysis of Minghui63 with special reference to photoperiod-sensitivity loci, using natural long days in Nanjing(32 degrees N) and natural short days in Linshui county, Hainan province (18 degrees 29'N), where the average day-length is about 14 h and 11.6 h during the course of rice growing, respectively. The F1 and F2 generations from the crosses "heading time nearly isogenic lines x Minghui63" were subjected to genetic analyses. Experimental results showed that Minghui63 carries photoperiod-sensitivity allele gene E1 and E3 in E1 and E3 loci, respectly, and a photoperiod insensitivity allele Se-1e in Se-1 locus, and it also carries a recessive inhibitor for photoperiod-sensitivity gene E1. Meanwhile, the photoperiod-sensitive genes, E1 and the photoperiod-insensitive genes, Se-1e, in Minghui63 were also identified by crossing with the nearly isogenic lines for heading time QTLs, NIL (Hd1) and NIL(Hd4). The results indicated that Minghui63's genotype of heading date was: E1E1e2e2E3E3Se-1eSe-1e. The result from this research indicated that Minghui63 carries a major dominant photoperiod-sensitive gene E1 in E1 locus, and our previous researches indicated that Zhenshan97A carried a major dominant photoperiod-sensitive gene Se-1n in Se-1 locus and a recessive inhibitor gene i-Se-1. The DH of the hybrid rice "Shanyou63" is 94.7 in Nanjing, lying between Zhenshan97A's and Minghui63's, but more nearer to late maturity parent Minghui63. It has been not expressed that E1 gene usually prolongs days to heading by about 20 days when coexisting with Se-1u or Se-1n. This is possibly made by that inhibitor genes exist in respective parents, which make DH transgression of "Shanyou63" not appear. This phenomenon indicated that the heading date of indica hybrid rice is resulted from the interaction among the photoperiod-sensitive genes and their inhibitor genes in the sterile and the restorer lines.