Abstract:

An indica variety, Kasalath, is highly resistant to rice stripe virus and small brown planthopper. In order to dissect the relationship between rice stripe virus and small brown planthopper resistance genes, the QTLs were detected using Nipponbare/Kasalath//Nipponbare backcross inbred lines. One putative QTL (qSTV11) for the ratio of disease rating index was mapped between the marker S2260 and G257 on chromosome 11, which explained 35.79% of the total phenotypic variation with LOD score of 9.2. The positive resistant effect came from Kasalath. The two QTLs (qSBPH3-a, qSBPH3-b) for non-preference index were detected on chromosome 3, and their contributions to the total variation were 11.69% and 11.36% with LOD scores of 3.12 and 2.96, respectively. This suggests that the rice stripe virus and small brown planthopper resistance are controlled by different genes and this view is testified by no significant correlation between RSV and SBPH resistance. Then, two pairs of epistatic QTLs for ratio of disease rating index and non-preference index were respectively detected, showing the rice stripe virus and small brown planthopper resistance were influenced by main-effect QTLs and epistatic QTLs. Additionally, further study found that SSR marker BJ11-8 was tightly linked to qSTV11. This facilitates the breeding process for resistance to rice stripe disease by marker-assisted selection.

Key words: Rice stripe virus, Laodelphax striatellus Fallen, Backcross inbred lines (BILs), QTL analysis, Epistasis