Qtl Mapping Of Panicle Neck Length And Plant Height In Rice(oryza Sativa L.) Based On CSSL Derived From Ⅱ-32B(Indica) And A7444(Japonica)

Rice is one of the most important food crops in the world.The utilization of rice heterosis makes rice yield greatly improved.China’s hybrid rice planting area accounts for half of the total acreage,and hybrid japonica rice only occupied 5%of hybrid rice.There is a lot of room for development of hybrid japonica rice.At present,BT-Type CMS lines are the most widely used CMS lines in three-line hybrid japonica rice in China.In the process of hybrid seed production,the phenomenon of sheathed panicle is an important factor to limit seed production.The application of gibberellin can unsheath the panicles and improve out-crossing rate.It is of great value to reduce the cost of hybrid seed production by breeding long-necked rice material and reducing or eliminating the application of gibberellin.Therefore,this study used the CSSL(Chromosome segment substitution lines),which was constructed by using an indica maintainer line Ⅱ-32B as receptor and the long-panicle-neck japonica native variety A7444 as donor parent.QTLs for panicle neck length(PNL)were detected by QTL IciMapping 4.0 software in combination with genotype data of SSR markers and the panicle length of phenotype data survey in 2014,2015 and 2016.At the same time,in order to screen the QTLs of panicle neck length,but not affect the plant heigth,the plant height trait was alse studied.The main results obtained are as follows.1.A total of 9 QTLs for panicle neck length were identified in three environments.which were distributed on chromosomes 1(2 QTLs),3(2 QTLs),8,10(2 QTLs),11 and 12.The contribution rates of the phenotype ranged from 6.1%to 44.05%.The additive effect of qPNL1.2,qPNL8 and qPNL10.1 was from the recipient parents,and the rest were from the donor parents which ranged from 2.15cm to 6.47cm.qPNL1.1 and qPNL10 were detected in three environments,qPNLl.l explained phenotypic variation of 17.84%to 34.05%;qPNL10 explained phenotypic variation of 24.80%to 50.18%;qPNL1.2 was detected in two environments in 2014 and in 2015,and the contribution rates were 18.92%and 17.51%,respectively.The additive effect were 3.87cm and 3.41cm,respectively.2.Four QTLs related to plant height were detected in the 3-year environment,which were distributed on chromosomes 1,3,6 and 12 respectively.The contribution rate to phenotype ranged from 8.45%to 59.05%,The increasing effective allele of qPH12 was from the Ⅱ-32B and the additive effect was 17.45cm.The rest of the loci were from A7444 and the additive effect ranged from 6.91cm to 26.22cm;qPHl were detected in three environments to explain the phenotypic variation of 30.27%to 59.05%;qPH3 in two environments were detected,explained phenotypic variation of 8.45%to 9.54%.3.It was found that 3 alleles,RM1246、RM6696 and RM3564 markers at the site of the A7444 allele can increase plant height and panicle neck length,RM1246 marker was detected only in a year.The QTLs of plant height and panicle neck length detected in this study can provide molecular marker information for genetic improvement of panicle neck length trait.