QTLs Analysis For Main Agronomic Traits Using Chromosome Segment Substitution Lines Of Dongxiang Common Wild Rice (Oryza Rufipogon Griff.)

At present,the genetic basis of cultivated rice varieties in China is narrow,and its genetic diversity is obviously less than that of wild rice.The single genetic background of the parent material used in breeding is one of the important reasons for the stagnation of breeding at present.The wild rice resources contain the excellent genes of disease and insect resistance,resistance to stress and agronomic traits that were lost in cultivated rice.The exploration of QTLs related to agronomic traits in wild rice will be of great significance in broadening the genetic basis of cultivated rice varieties,enriching the genetic resources of rice breeding and improving the level of breeding.In this study,the QTLs of the main agronomic traits of rice were located and analyzed by using the chromosome fragment replacement lines covering the whole genome of wild rice constructed from Dongxiang common wild rice(C35)as the donor parent and the japonica rice variety Nipponbare as the recipient parent.After rice ripening,12 main agronomic traits including plant height,panicle characters and grain characters were investigated and statistically analyzed.QTL positioning analysis was performed using QTL Ici Mapping 4.1.0 software.The main findings are as follows:(1)A total of 74 QTLs related to major agronomic traits were detected in this study,which were distributed on 12 chromosomes of rice and concentrated on chromosomes 1,2,3,4,6 and 8.Including,4 plant height related QTLs,the contribution rate was between 8.97 and 20.05%.The contribution rate of 45 panicle traits related QTLs ranged from 4.75 to 27.90%.The contribution rate of 25 grain trait related QTLs ranged from 6.95 to 18.49%.Among all QTLs,the positive additive effect of 54 QTLs was derived from alleles of Dongxiang common wild rice.(2)Of all QTLs,10 can be detected repeatedly in two or three environments.Among them,the contribution rate of 5 QTLs was more than 15%,including plant height q PH2,with an average contribution rate of 15.48% in multiple environments.Panicle length q PL2-2,with an average contribution rate of 15.35%.The average contribution rate of primary panicle grain number q PBGN8-2 was 17.34%.Grain length q GL3-4,with an average contribution rate of 15.80%;The average contribution rate ofgrain width q GW8 was 16.55%.Among the 10 QTLS detected,the control of primary panicle number q PBPP1-2 located near the marker 01-046 of chromosome 1 and had not been reported,and further verification is needed.(3)The QTLs related to agronomic traits were clustered on chromosomes 1,2,3,4,6,8 and 11.The two QTL clusters detected near 02-067～DX-C2-13 labeled region of chromosome 2 and DX-S8-14～DX-C8-15 labeled region of chromosome 8 showed high reproducibility in multiple environments.(4)In this study,a total of 14 excellent character replacement lines and 3 excellent comprehensive character replacement lines were selected.Among them,CSSL17,CSSL34 and CSSL63 had excellent comprehensive traits,11 agronomic traits of CSSL17 in Beijing,Linyi and Nanchang environments,plant height and panicle traits of CSSL63,and plant height,panicle length and grain traits of CSSL34 were superior to those of the background.