| The plant type is a significant morphological trait of the characteristics of rice(Oryza sativa L.),of which the internode diameter and panicle size are important indicators of the ideal plant type of rice,which are closely related to the lodging resistance and yield of rice.It is of great significance for the molecular breeding of rice ideal plant type to study the related QTL of rice internode diameter and panicle length traits by using QTL mapping.In this study,G46 B with thick internode and short panicle was used as the male parent,and A232 with spindly internode and long panicle was used as the female parent.By using the RIL populations constructed by hybridization of the two parents and the high-density genetic linkage map constructed by resequencing the populations,the QTL for internode diameter and panicle length in Hainan and Wuhan in 2019 and 2020 were mapped and analyzed by CIM method,the results are as following:1.The correlations of internode diameter and panicle length of RIL populations were different under different environmental conditions.There was a significant positive correlation between internode diameter and panicle length in Wuhan,but there was no correlation between internode diameter and panicle length in Hainan.2.The QTLs of internode diameter related traits include 3 QTLs of inverted second internode stem diameter,7 QTLs of inverted third internode stem diameter,and 6 QTLs of head internode stem diameter.16 QTLs were located on chromosomes 2,3,4,7,and 11,with the variation range of phenotypic contribution rate of 1.24% to 12.36%.This is 1 major internode diameter QTL site q RTID2-1,with the phenotypic contribution rate of 12.36%.q RSID2-1 is identified in Hainan and Wuhan,with the phenotypic contribution rate of8.26%～9.09%.The analysis revealed several QTLs with close physical and genetic distances,which were considered to be the same QTL in this study,including q ID2-1 and q ID2-2,with maximum LOD values of 9.70 and 5.82,and maximum phenotypic contributions rate of 12.36% and 9.22%.Among them,q ID2-2 was detected in the internode diameter traits of different internodes,which may control the internode diameter traits of the whole upper part of rice.5 QTLs of panicle length were located in chromosomes2 and 3,with the variation range of phenotypic contribution rate of 0.07% to 3.90%.The panicle length phenotype of the RIL populatios in Hainan showed a larger skewness and smaller coefficient of variation compared to Wuhan,which led to the fact that no QTL for panicle length with LOD value greater than 2.5 was detected in Hainan.3.Multiple QTLs for internode diameter and panicle length were detected on chromosome 2 and distributed in clusters,including q ID2-1,q ID2-2,q PL2-3,and q PL2-4.And q PL2-3 and q RSID2-1 were the same QTL locus,which were located in the interval of q ID2-1;q PL2-4 and q ID2-2 may be the same QTL because they were close to each other.It was indicated that these QTL clusters may have pleiotropism or multiple closely linked genes to affects the internode diameter and panicle length of rice.4.Based on the resequencing data of parents,the variation analysis and function prediction of genes in the range of 100 kb upstream and downstream of QTL candidate interval were carried out,and 20 candidate genes that may be related to internode diameter and panicle length were screened.Os R498G0204987500.01 is the key candidate genes. |
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