Four rice QTL controlling number of spikelets per panicle expressed the characteristics of single Mendelian gene in near isogenic backgrounds |
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Authors: | Yushan Zhang Lijun Luo Touming Liu Caiguo Xu Yongzhong Xing |
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Institution: | (1) National Key Laboratory of Crop Genetic Improvement, National Center of Plant gene Research (Wuhan), Huazhong Agricultural University, 430070 Wuhan, China;(2) Shanghai Agrobiological Gene Center, 2901 Beidi Road, 201106 Shanghai, China |
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Abstract: | Development of quantitative trait loci (QTL) near isogenic lines is a crucial step to QTL isolation using the strategy of
map-based cloning. In this study, a recombinant inbred line (RIL) population derived from two indica rice varieties, Zhenshan 97 and HR5, was employed to map QTL for spikelets per panicle (SPP). One major QTL (qSPP7) and three minor QTL (qSPP1, qSPP2 and qSPP3) were identified on chromosomes 7, 1, 2 and 3, respectively. Four sets of near isogenic lines (NILs) BC4F2 targeted for the four QTL were developed by following a standard procedure of consecutive backcross, respectively. These
QTL were not only validated in corresponding NILs, but also explained amounts of phenotypic variation with much larger LOD
scores compared with those identified in RILs. SPP in the four QTL-NILs expressed bimodal or discontinuous distributions and
followed the expected segregation ratio of single Mendelian factor by progeny test. Finally, qSPP1, qSPP2, qSPP3 and qSPP7 were respectively mapped to a locus, 0.5 cM from MRG2746, 0.6 cM from MRG2762, 0.8 cM from RM49 and 0.7 cM from MRG4436,
as co-dominant markers on the basis of progeny tests. These results indicate no matter how small effect minor QTL is, QTL
may still express the characteristics of single Mendelian factor in NILs and isolation of minor QTL will be possible using
high quality NILs. Pyramiding these QTL into a variety will largely enhance rice grain yield. |
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