Fine Mapping Of A Heat Tolerance Gene And QTL Associated With Heading Date In The Rice(Oryza Sativa L.) Variety,996

With the intensification of the greenhouse effect, the rice heat injury, especially during the heading stage, is becoming an important meteorological factor affecting rice yield and its related traits. Deeply exploring heat-resistant genes and nurturing heat-resistant rice varieties are two effective ways to solve this problem. Early indica rice cultivars as important ecological type of double-crop modle in the South China, played an important role in ensuring the safety of grain production in China. It will be useful for molecular marker-assisted selection breeding and provide new genetic resources for early-season rice cultivar in Southern China by carrying out heading date QTL analysis.In this study, a set of recombinant inbred lines derived from a cross between a heat-resistant rice variety996and a heat-sensitive rice variety4628were used to carrying out QTL analysis of heading date. And the backcross F2population constructed on the basis of RILs, were used for fine mapping of a heat-resistant gene.The main findings are as follows:1. The density of marker on partial chromosomes will be increased of the996/4628RILs on the basis of the existing molecular marker linkage map. There were totally increased24tags, each of8tags increased in chromosome3,4and7. Ultimately, there were185molecular markers in the final linkage map. The185molecular markers located in12chromosomes, covering a total of2348.6cM of the rice genome, and contained16linkage groups. Among them, the markers on chromosome3,9and11distributed in3,2and2linkage groups, respectively.2. Identification of the upper part of the panicle seed setting rate in natural and greenhouse high temperature, a heat tolerance QTL was detected between the markers RM16770and RM16773on chromosome4. The LOD score, contribution rate and additive effect of the QTL were17.39,34.62and9.81in natural high-temperature conditions, while in the greenhouse high temperature conditions were19.24,35.89and9.46, respectively.The LOD score and contribution rate of the QTL in the greenhouse high temperature conditions are higher than the natural high temperature conditions. The allele from996was associated with the increased seed setting rate.3. For indicators by the seed seting on the upper half of panicle in natural high temperature of the phenotypic identification in the backcross F2population.The heat tolerance QTLwill be detected in the interval flanked by the markers RM16770and RM16792on chromosome4by genotype analysis of the material taken in the F2population, the genetic distance is2.5cM.4. After analyzed the RILs constructed by the cross between996and4628,7QTLs for heading date, named qhdl-1, qhdl-2, qhd2, qhd3, qhd7-l, qhd7-2and qhd10, were mapped on the chromosome1,2,3,7and10, respectively. Except qhdl-1and qhd1-2, the remaining five QTL were detected at least in two test environments and qhd3, qhd7-1and qhd7-2could be detected in12environments of4years. Among them, the QTL qhdl-1, qhdl-2, qhd3and qhd10contributed to prolong the heading date, while qhd2, qhd7-1and qhd7-2played opposite role.2large effect QTLs,qhd7-1and qhd7-2, were detected and mapped adjacently to RM21320-RM21364and RM3859-RM21101on chromosome7with the contribution rate19.00%-54.84%and18.31%-57.87%in different environments, shorten the heading date1.9-3.7d and1.9-3.8days, respectively.