Genotypic Analysis Of Heading Date On Main Hybrid Rice Parents And Transgressive Analysis Of F₁ From The Cross Between Indica And Japonica

Heading time is one of the most important traits for the adaptation of rice to different cultivation areas and cropping seasons. In rice, the genetic control of heading time is mainly determined by basic vegetative growth (BVG) gene Ef-1 (Yamagata et al. 1986; Okumoto et al. 1992; Tanisaka et al. 1992; Ichitani et al. 1997, 1998; Inoue et al. 1998 ) and photoperiod sensitive genes E1, E2, E3 and Se-1 (Luo et al. 2002; Ichitani et al. 1997, 1998), of which the two major genes, E\ and Se-1, are the main factors affecting rice cultivar's heading time (Yamagata et al. 1986, Ichitani et al. 1997, 1998). The action of E\ is far greater than those of E2 and E3, and the photoperiod sensitivity of E1 is considerably enhanced by the coexistence of E3, especially by that of both E2 and E3, which leads to the delaying of the heading time (Yamagata et al. 1986; Cai et al. 1987; Ichitani et al. 1997, 1998; Luo et al. 2001). On the other hand, the recessive inhibitor gene i-Se-1 for photoperiod sensitivity can cause early heading even under long-day condition, it is reported that there is a recessive inhibitor gene i-Se-1 in most early indica rice cultivars (Ohshima et al. 1993, 1994; Luo et al. 2002 ), therefore, these early indica rice cultivars don't show photoperiod sensitivity even if they carried the photoperiod sensitivity genes themselves.In the present paper, the molecular basis of distinct late-transgressive derived from the cross between Indica and Japanica was analyzed. The genotype of heading date in main cultivars which were broadly cultivated in China were analyzed using heading time isogenic lines EG0-EG7, ER~LR> T65~T65m and six heading date QTL-isogenic lines. 1. Genotypic analysis of heading time on main rice cultivarsPeiAi64S, II-32A, the elite rice male sterile line, has been widely applied to hybrid rice seed production in China. 9311, TeQing, the rice cultivars were widely grown in China in 1980s and 1990s, in addition, these two cultivars were used as the restorer line of two lines now. Clarifying the heading time genotype of these cultivars, and discussing the genetic base of hybrid rice with broadly adaption in these cultivars as parents, which provided the theories base for breeding strong heterosis's combinations. The genotype of heading date in main cultivars were analyzed using heading time isogenic lines EG0~EG7, ER~LR, T65~T65m and six heading date QTL-isogenic lines, NIL (Hdl) ~NIL(Hd6) with the background of Nipponbare and Hd1~ Hd6 genes from Kasalath respectively, we performed a genetic analysis of these cultivars with special reference to photoperiod-sensitivity loci, in natural long days at Nanjing (32 N) in China where the average day-length is about 14 h and in natural short days at Linshui county, Hainan province (18 29'N), about 11.6 h during the course of rice growing respectively. The results are as follow:(1) PeiAi64S carried Ei, e2, and E3 genes at the Ei, E2, and E3 locus, and it carried a photoperiod insensitivity gene Se-le at the locus Se-1. At the same time, PeiAi64S carried a dominant early flowering gene Ef-1 at the loci Efl.(2) II-32A carried two dominant photoperiod sensitivity genes E1 and Se-1n at the E1 and SW locus, and it carried a recessive modified photoperiod sensitivity gene e2 and a dominant modified photoperiod sensitivity gene E3 at the locus E2 and E3. At the same time, II-32A carried a recessive late flowering gene ef-1 at the loci Efl.(3) 9311 carried three dominant photoperiod sensitivity genes E1, E2, and E3 genes at the Ei, E2, and E3 locus, and it carried a photoperiod insensitivity gene Se-le at the locus Se-1. At the same time, 9311 carried a recessive late flowering gene ef-1 at the loci Efl.(4) TeQing carried a dominant major photoperiod sensitivity genes E1 at the E1 loci, a recessive modified photoperiod sensitivity gene e2 and a dominant modified photoperiod sensitivity gene E3 at the locus E2 and E3. a photoperiod insensitivity gene Se-1e at the locus Se-1. At the same time, TeQing carried a dominant early flowering gene Ef-1 at the loci Efl.(5) The...