| Rice is an important cereal crop that provides food for more than half of the world’s population.The QTL(quantitative trait loci)research on agronomic characters of rice provides theoretical and application significance for cloning key genes,revealing yield components and exploring the correlation between rice yield and plant and grain type.A rice genetic linkage map was constructed on the basis of 158 polymorphic molecular markers and the 188-line recombinant inbred lines(RILs).The RILs deprived from selfing 7 generations by single seed descent method from the cross between Chunjiang16B(CJ16B,the late japonica maintainer line)and C84(the mid-indica restoration lines),which were the two parents of super hybrid rice Chunyou 84 and relatively different in plant and grain morphology.The main results were described as follows:A rice genetic linkage map was constructed on the basis of 158 polymorphic molecular markers well distributed and the RILs containing 188 lines of CJ16 B and C84,with the total genetic distance of 1428.40 cM and average density of 9.04 cM,ranging from 0.2 cM and 43.3 cM.The location and order of each marker were in agreement with the published Nipponbare sequence,meeting the basic requirements for QTL mapping.The linkage map was used to detect QTLs related to five traits such as grain length(GL),grain width(GW),grain thick(GT),length-to-width ratio(LWR)and thousand grain weight(TGW)in Hangzhou and Hainan.A total of 30 QTLs were detected in two sites,and the contribution rates ranged from 3.51% to 17.25%.The number of QTLs related to GL,GW,GT,LWR and TGW were 9,5,5,6 and 5,respectively;Gene locus alignment shows that five cloned genes of grain shape were found in the QTL marker interval,which were identified with sequencing of parental target genes and dCAPs molecular marker.It showed that the genetic map can be used for the genetic analysis of grain morphology and the main effect QTLs positioning.The linkage map was used to detect QTLs related to eight traits including plant height(PH),tillering number(TN),the length and width of the top-three leaves(flag leaf length(FLL),flag leaf width(FLW),the 2nd leaf length to the top(SLL),the 2nd leaf width to the top(SLW),the 3rd leaf length to the top(TLL),the 3rd leaf width to the top(TLW))in RIL population.A total of 27 QTLs were detected in two sites.There were 4 QTLs of PH,1 QTLs of TN,and the number of QTLs related to FLL,FLW,SLL,SLW,TLL and TLW were 2,2,6,4,5 and 3,respectively;It explained genetic effect ranging from 1.85% to 82.09%,Which lays the foundation of cloning new genes related to plant type reglution network and leaf morphological development.A QTL qLL9 of leaf length contributes 82.09% in the interval of RM3700-B9-11 on chromosome 9.QTLs were detected of PH,TN,SLW and TLW simultaneously,which contribution rates ranged from 20.75% to 82.09%,and the QTL positions were overlapped or linked.It is predicted that there were multiple genes related to plant type regulation linkaged closely or a pleiotropic main effect QTL on plant leaf morphology simultaneously.Selected heterozygous individuals from the lines associated with this fragment to form the remaining hybrids,a major QTL for leaf length,qLL9 was fine mapped within 35.56 kb between two Indel markers Chr9-1638 and Chr9-1642 on chromosome 1,which contains seven open reading frames. |
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