| Growth duration or heading time is an important agronomic trait, which is responsible for the regional and seasonal adaptation of rice varieties。Heading time is important agronomic traits for breeders to improve rice. To breed the appropriate heading date is alway pursuit for breeders. In the research, heading time for rice was studied using Koshihikari/Kasalath// Koshihikari BILs, Koshihikari/Guichao 2 RILs, Nanjing11/ Koshihikari RILs, Kasalath/Koshihikari CSSLs and Peiai64S/93-11 CSSLs. The results as follows:1 The Quantitative Trait Loci for Rice Heading Time in KoshihikariIn order to verify the quantitative trait loci for rice heading time in Koshihikari, QTL mapping of heading time was studied using both Koshihikari/Kasalath// Koshihikari BILs population and Kasalath/Koshihikari CSSLs population in Nanjing, Jiangsu province and Lingshui, Hainan province. The results indicated that:three QTLs of heading time were detected, whichwere located on chromosomes 3,6 and 8, respectively. At qHd-3 and qHd-8 loci, the allele from Koshihikari can promote heading time for rice, but at qHd-6 loci, the allele from Koshihikari could delay heading time for rice. Epistatic interaction was detected between qHd-3 and the QTL located on chromosome 7. Comparing BILs with CSSLs linkage maps, we found that the marker regions of qHd-3, qHd-8 and qHd-7-1 coincided with Kasalath segments in W008, W023 and W024, W020, respectively. Meanwhile, QTL mapping of heading time was studied using Koshihikari/Guichao 2 RILs population, three QTLs were detected and epistatic interactions were detected between two QTL of heading time.2 Mapping of QTL Controlling Heading time in Rice Using Nanjing11/Koshihikari RIL PopulationA molecular linkage map, consisting of 153 SSR markers spanning a total of 1,896.2 cM was constructed, with an average marker interval of 12.3 cM, was constructed using 140 lines with the Nanjing11/ Koshihikari RILs population. Markers order on the chromosomes agreed well with that of the published map. QTL controlling heading date was detected using Nanjing11/ Koshihikari RILs population under natural-field and short-day condition in Nanjing and natural-field and greenhouse condition in Hainan. A total of 5 QTLs were identified with significant additive effects on 1,3,6,8 and 10 chromosomes. qHd-1, a high-temperature sensitive QTL, only was detected under high temperature-short day condition. qHd-6 and qHd-10 were detected under low temperature-short day condition. qHd-3 and qHd-8-1 were detected under long-day condition. Epistatic interaction was detected between two non-additive QTLs of heading time under high temperature in Nanjing and short-day condition in Hainan, respectively. The results suggest that rice heading date was controlled by additive and epistatic QTLs as well as QTLs interaction of environment (QE) effect.3 Analysis for Heading Date QTLs in Rice Using Peiai64S/93-11 Chromosome Segment Substitution LinesIn this research, a set of Peiai64S/93-11 chromosome segment substitution lines (CSSLs) with Peiai64S as donor was used to detect QTLs for heading date, through compared the heading date between each line and the recipient parent 93-11 under 2 condtions in Nanjing (natural long-day (about 13.2-14.2hL/9.8-10.8hD, E1) and artificial short-day (9hL/15hD, E2)) and Hainan (greenhouse (high temperature, E4), and natural low temperature (E3)) conditions, respectively. QTLs were identified by t-est with a significance of P=0.001. A total of 21 QTLs for heading date were located on 10 rice chromosomes with the exception of chromosomes 6 and 10. Furthermore, the characteristic of these QTLs response to photoperiod and temperature was analyzed. The results showed that 2 QTLs have photoperiod sensitive,8 QTLs inhibit to photoperiod sensitive,2 QTLs have tempreture sensitive,4 QTLs inhibit to tempreture sensitive, and 5 QTLs belong to earliness genes. A F2 population developed from a cross between C053 and 93-11 was used to map the earliness QTL qHd-8-4. This earliness QTL was located on the chromosome 8 between marker RM22496 and RM72 with genetic distances of 2.6 cM and 3.5 cM, respectively. |
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