Zhai HuQu

Screening of rice resources against rice black-streaked dwarf virus and mapping of resistant QTL.

Rice black-streaked dwarf virus(RBSDV)disease become epidemic in Jiangsu and Zhejiang provinces. To screen resis- tant germplasms and discover new resistance genes/QTLs against RBSDV, we evaluated the resistance to RBSDV in 311 japonica cultivars in field test. The results showed that no cultivar was immune to RBSDV. The disease rate of 24 main japonica cultivars grown in Jiangsu province at present was 10.0%-29.0% and that of 71.5% cultivars in 287 japonica cultivars popularized in Ji- angsu before was between 10.0% and 30.0%. Furthermore, quantitative trait loci (QTL) analysis was conducted by using 162 recombinant inbred lines (RILs), which derived from a cross between Guichao 2, a susceptible indica variety, and Koshihikari, a japonica variety with resistance to RBSDV. RBSDV resistances were evaluated using natural infection methods by scoring the disease rating. One putative QTL (qRBSDV3) controlling RBSDV resistance was mapped between the marker RM7 and RM5748 on chromosome 3, which explained 17.1% of the total phenotypic variation with LOD score of 5.4. The positive resistant effect contributed from Koshihikari. Further analysis revealed that the lines harboring the alleles of qRBSDV3 exhibited significantly increased resistance to RBSDV. The results should be very useful for breeding new RBSDV-resistant cultivars by marker-assisted