Development Of Single Segment Substitution Lines(SSSLs) Of O.rufipogon In The Background Of Indica Cultivar “HJX74” And Identification Of QTLs For Important Traits

By long term of artificial selection,the population genetic diversity of cultivated rice(O.sativa L.)is decreased and become fragile,which restricts the breeding of new cultivars.In contrast,by extended natural selection,wild ricemaintains a strong adaptability and resistance to the environment.It is an effective way to improve the genetic diversity of cultivated rice by introducing a certain chromosome segment of wild rice into cultivated rice,constructing a batch of single segment substitution lines(SSSLs)and further digging the excellent traits gene of wild rice.In this study,series of SSSLs of O.rufipogon in the background of elite cultivar HJX 74 were developed through crossing and repeat backcrossing,assisted with marker assistant selection(MAS).Here are the main results:1?114 unique SSSLs were obtained,and the total length of the substitution segment was 1894.65 cM,which was equivalent to 1.24 times of the size of the rice genome,covering 834.65 cM in length,covering 54.77% of the rice genome,of which 9 chromosomes covered more than 50%.2?QTLs of 20 different traits were detected with 51 and 93 SSSLs in the early and late seasons in 2016,respectively.A total of 236 QTLs were identified in the two seasons.Among them,99 were detected only in early season and 184 only in late season;44 QTLs were detected in both seasons.Except for total grain number,QTLs of other 19 traits were found: 13 Q TLs forheading date,21 Q TLs for plant height,7 Q TLs for length of top first leaf,12 QTLs for width of top first leaf,5 QTLs for number of panicles,7 QTLs for neck long,3 QTLs for panicle length,4 QTLs for number of primary branches per panicle,2 QTLs for Percent seed set,25 QTLs for thousand grain weight,17 QTLs for grain length,11 QTLs for grain width,15 QTLs for the ratio of grain length to width,22 QTLs for percentage of exserted stigma,19 QTLs for stigma length,19 Q TLs for total stigma length,16 QTLs for stigma width,11 QTLs for anther length,7 QTLs for anther width.Percentage of additive effect about these traits ranged from 0.60%(qGL8-2)to 378.77%(qNL8-1).63.56% of the Q TLs showed positive-effect.3?With contigs of SSSLs,49 QTLs were mapped in 10 c M,among them,both q HD12-1 and qGWT12-2 were narrow down into 3.20 c M.4?4 new Q TLs were first time found in the 14 major QTLs of this study,likeqNL8-1,qNL9-1,qPES3-1,andqPES12-1,respectively,with a lot of use value.5?Traits of red grain color,black hull,spreading panicle,and awn were found in SSSLs,traits of spreading panicle and awn might be the new traits..A set of SSSLs of O.rufipogon were developed in the background of HJX 74,and series of QTLs were detected using these SSSLs.These achievements enriches SSSL library of our laboratory and provides clues for fine mapping and utilization of ideal traits of O.rufipogon.