Abstract:

In order to verify the quantitative trait loci for rice stripe in rice cultivar IR24, QTL mapping of resistance to rice stripe was studied using both recombinant inbred lines (RIL) and a series of IR24 chromosome segment substitution lines (CSSLs) with Asominori genetic background. Four QTL were detected and located on chromosome 3, 5, 7,11, respectively, (qSTV3, qSTV5, qSTV7, qSTV11) using RIL population by natural condition test in the infected rice field. The positive resistance effects at qSTV3, qSTV7 and qSTV11 were from IR24. A graphical genotype analysis of the CSSL population indicated that the IR24-derived segments presented in five lines with QTL conferring rice stripe resistance. Comparing RIL with CSSL linkage maps, we found that the marker regions of qSTV3, qSTV7 and qSTV11 coincided with IR24 segment in CSSL17, heterozygous segment in CSSL4 and IR24 segment in CSSL39, and IR24 segment in CSSL61 and heterozygous segment in CSSL62, respectively. Additionally, qSTV3 was arranged on a gene cluster of chromosome 3 associated with sucking insect resistance, suggesting it be a new and stable expression locus, and qSTV7 be another new QTL detected in this research, after comparing with previous reports. These results indicated that IR24 carried several new resistance genes controlling rice stripe. This will provide a new resistance resource for avoiding genetic vulnerability from single resistance gene, Stvb-i, and provide a foundation for breeding rice varieties with stable resistance to rice stripe by diversifying rice stripe virus and small brown planthopper resistance genes in MAS.

Key words: Rice stripe, Laodelphax striatellus Fallen, Resistance, Quantitative trait locus (QTL)