QTL Mapping On Heading Date And Its Relation With Yield Traits Of The RIL Population Derived From XY9308, A Super Hybrid Rice(Oryza Saiiva L.)

Super rice breeding, as the third revolution after semi-dwarf breeding and heterosis utilization, canincrease rice production in a substantial content and effectively alleviate the food security of China andthe whole world. However, as a offspring of indica and japonica, growth stages of super rice usualappear transgressive late-maturing phenomenon and F1spikelet fertility is sensitive to environment.Those serious problems influence the application value of super rice. Heading date and yield traits, areimportant agricultural traits that determine the value of rice, therefore, studing the genetic control ofboth relations would be of great significance for the super rice breeding and spread.A recombinant inbred lines (RIL) population derived from a cross of XQZB/ZH9308of a superrice Xieyou9308was used as materials in this study. Identify and analyze the QTLs for heading date,photoperiod sensitivity of heading date, developmental behaviour of leaf number and yield trait werecarried out for two consecutive years under three different conditons. The main results were as follows:1,A total of262RILs derived from XQZB×R9308, the parents and F1were planted in ZhejingFuyang, Guangxi Nanning and Hainan Lingshui in rice-growing season of2010and2011. Phenotype ofheading date at the two consecutive years under three different conditons which were combined withmolecular genetic linkage map, used winQTL Cart2.5software, was developed for mapping andanalyzing the QTL. A total of10QTL significantly affect heading date were located in chromosome4,5,6,7,8and10, the detected QTL individually accounted for2.39%-21.24%of the phenotypic variation.qHd7-6, relatively stable expression, had been detected at two years of trials in Fuyang and Nanning,accounted for the phenotypic variation ranged from7.29%to18.75%, which positive allele came fromthe male parent ZH9308. qHd6-1could be detected in two trials station and additive effect came fromXQZB. The other8QTL of heading date could only be detected in a test point.2,15QTLs controlling heading date across three environments at two years were analyzed byMCIM-based methods of analysis, used QTLNetwork2.0.4pair of QTL had significant levels additive×additive epistatic effects, which was qHd6-1to qHd7-17, qHd6-10to qHd10-6, qHd5-13to qHd6-20and qHd6-10to qHd8-3. The proportion of phenotypic variation explained by individual additive QTLranged from0.30%to3.53%.8QTLs were founded to be affected significantly by environments, whichwere qHd1-15, qHd4-2, qHd5-1, qHd6-4, qHd6-10-6, qHd7, qHd10-6. The contribution rate of a singleQTL was small, and qHd10-6of10chromosomes was the largest of them, for1.28%. Besides theqHd10-6, the contribution rate of QTL×environment interaction effects of the other QTL were lessthan its additive effect.3,One RIL population with150lines, the parents and F1, treated by artificial short day (10h/d),were developed for mapping QTLs in Fuyang at2010and2011. A total of3QTL for photoperiodsensitivity, qPs5-1, qPs7-6, qPs11-8, were detected on chromosomes5,7and11, the detected QTLindividually accounted for6.75%-15.00%of the phenotypic variation. Positive allele of all the3QTLcame from ZH9308. Among the3QTLs, qPs7-6could stably express and be likely to same locus or a allele with Ghd7and E1, according to its position on the chromosome.4,150lines of the RIL population, parents and F1, and its genetic linkage map were used toidentify QTLs for the developmental behavior of leaf number, by using conditional composite intervalmapping method.5uconditonal QTL, QTL qLN2-1,qLN2-2,qLN2-3and qLN2-4, were detected onchromosomes2,2,2,2and4during6periods of all the9investigate periods, explaining10.16%-18.40%of phenotypic variation. Among the5uconditonal QTL, qLN2-1and qLN2-4could bedetected in two stages.2conditions QTL, qLN2-1and qLN2-4, were detected only in a stage, whichpositive allele came from XQZB and accounted for13.8%and10.17%of the phenotypic variation. Thecorresponding unconditional QTL could be detected in the same period. QTL analysis showed that theexpress period of conditional QTL, qLN2-2and qLN2-4, were unanimous to the date of elongating andheading of RIL population. qLN2-1, qLN2-2, qLN2-3and qLN2-4tend to distribue in cluster, and somerelevant QTL for heading date may locate in this the QTL clusters according to high correlation betweenleaf number and heading date.5,A total of260RILs, parents and the F1were planted in Zhejiang Fuyang and Guangxi Nanningin rice-growing season. The main yield traits were observed included productive panicles(PP), numberof spikelets per panicle(NSPP), number of filled grain per panicle(NFPP), spikelet fertility(SF),1000grain weight(TGW), panicle length(PL), plant height(PH) and grain yield per plant(GYPP). Thephenotype of eight traits was used for QTL analysis, combined with molecular genetic linkage map. Atotal of18QTLs for these8main yield traits were detected on chromosomes1,3,6,7,8and9,explained7.20%-24.52%of the phenotypic variation. Among these18QTLs, there were4QTL for PH,3QTL for NSPP, NFPP and PL,2QTL for PP,2QTL for TWG,1QTL for GYPP. There were10QTL,qPh3-16, qPp3-9, qPh7-6, qPp8-13, qPl6-12, qPl9-13, qNspp1-14, qNfpp7-6, qTgw3-7and qTgw6-17,could be detected in two trial station. Correlation analysis showed that there were or significantcorrelations between heading date(HD), PH, PL, NSPP, NFPP, GYPP in every two trait. However, HDand PH were significantly negatively PP. PP, NSPP and TWG, as the three elements of GYPP, werewere significantly positive related to GYPP. There were complicated correlations between the othertraits.6,By compared the physical position in chromosome and sequence alignment between thesequence of QTL been clond with it of the parents, the QTL, be detected in this study, qHd4-2andHd11,qHd6-1, qHd6-3and Hd3, qHd6-10and Hd1, qHd7-6and Ghd7, was likely to be allele. Tgw3-7,a QTL for TGW in chromose3, was potential a allele to GS3, a major QTL been cloned for grain lengthand grain weight.The interval in chromosome7, contain qNfpp7-16for NFPP and qPh7-16for PH, waspotential a allele to qSSP7, a QTL been cloned.7,Wide adaptability of super rice was the second phase breeding target after high yield been done.Trait of heading date and yield were determinants for wide adaptability of super rice andphotosensitivity play an important role. In China, Japonica varieties, which as a middle-season rice or alate rice, had a relatively strong photosensitivity, while Japonica varieties in Northeast had weakphotosensitivity. Therefore, japonica source of restoring line should be selected according to the length of sunshine of each rice area. Japonica varieties with strong photosensitivity could be used as originalparents or intermediate parents under short day conditions. While in middle-season rice ofsingle-season-rice and late rice of double-season-rice area under long-day conditions, weakphotosensitive or nonphotosensitive japonica rice cultivars could be used as original parents orintermediate parents for restoring line. Th E1, a locu with strong photosensitivity, should try to be avoidusing in restoring line.