| Wild rice is an important gene pool for genetic improvement of rice varieties,which retains many favorable traits through long-term natural selection.O.australiensis belongs to wild rice with EE genome of the genus Oryza,which has a large reproductive isolation from cultivated rice with AA genome.In this study,a set of chromosome segment substitution lines containing 67 lines was constructed by combining backcross and molecular marker-assisted selection with O.australiensis and Nipponbare as parents,and QTL was mapped for major agronomic traits.The results are as follows:1.A total of 1114 molecular markers(889 SSR markers and 225 Indel markers)were developed between hybrid parents of O.australiensis and Nipponbare.A total of 291 markers were detected to be polymorphic between the parents,and the polymorphism frequency was 26.12%.2.In this study,a set of chromosome segment substitution lines containing 67 lines was constructed and identified based on the chromosome segment substitution lines from O.australiensis preliminarily constructed by our research group,combined with molecular marker-assisted selection and multi-generation backcrossing,including 5 BC2 lines,19 BC3 lines,1 BC4 lines,4 BC5 lines,3 BC6 lines,33 BC7 lines and 2 BC8 lines.The total length of the 42 lines of BC5 generation and above carrying O.australiensis fragments was 1328.7 Mb,the total coverage length was 89.5 Mb,and the total coverage rate was 23.98%.3.The main agronomic traits of 42 high generation substitution lines were investigated,and it was found that the data of these agronomic traits were normally distributed.Except for tiller number,other agronomic traits were significantly different from the corresponding traits of receptor parents.There was a certain correlation between the agronomic traits.4.In this study,35 QTLs related to agronomic traits were detected on 9 chromosomes.(1)A plant height QTL was identified on chromosome 11,with the contribution rate of 32.93%and additive effect value of 19.34.(2)Six QTLs for grain length were detected on chromosomes 1,5,10 and 12,with contribution rate ranging from 2.88%to 4.02%and additive effect ranging from 0.44 to 0.60.Eight QTLs for grain width were detected on chromosomes 1,2,3,5,10 and 12,with contribution rate ranging from 3.88%to 5.49%,and negative additive effect ranging from0.26 to-0.15.Fourteen QTLs for grain length-width ratio were detected on chromosomes 1,2,3,5,9,10,11 and 12,respectively.The contribution rate was between 2.60%and 4.19%,and additive effect was between 0.31 and 0.44.(3)A QTL for flag leaf length and flag leaf area was detected on chromosome 7,with the contribution rate of 30.61%and 33.39%,respectively,and additive effect value of 3.15 and 5.76,respectively.A flag leaf width QTL was detected on chromosome 10,with the contribution rate of 32.51%and additive effect value of 0.12.(4)A QTL for primary branch number was detected on chromosome 1,with the contribution rate of 30.94%and additive effect value of 0.94.A QTL for grain number per panicle was detected on chromosome 12,with the contribution rate of 35.29%and additive effect value of 31.40.(5)A QTL controlling 1000-grain weight was detected on chromosome 3,with the contribution rate of 23.57%and additive effect of-1.15. |
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