| Rice stripe, caused by rice stripe virus (RSV), is one of the most damaging diseases in temperate regions of East Asia, in particular China, Japan and Korea. RSV is transmitted by the small brown planthopper (SPBH, Laodelphax striatellus Fallen). In China, rice stripe is increasing in severity, particularly in Jiangsu province, where approximately 0.6Mha per year of rice were infected by RSV in the period 2000 to 2003, rising to 1Mha in 2004. Rice yield is reduced by 30-40% in heavily infected fields, and in some of the most infected fields, no harvest is possible. Commonly, rice stripe is controlled by pesticide application, but since this is both costly and polluting, there is a growing interest in the introduction of virus-resistant cultivars.In this study, resistance to rice stripe in 314 rice landraces from 12 localities of China was identified. Mechanism of resistance to RSV and SBPH in 8 varieties was analyzed. Then, QTL for RSV and SBPH resistance in 'IR24', 'IR36', 'Kasalath' and 'Zhaiyeqing 8' was detected. The results were as follows:Out of the 314 rice landraces from 12 localities of China, 68 entries were highly resistant, 25 moderately resistant, 93 moderately sensitive, 128 highly sensitive. And then the mechanism of resistance to RSV and vector, SBPH was studied and analyzed in eight indica rice varieties by using individual inoculation, mass inoculation, non-preference test and antibiosis test. The results indicated that the mechanism of resistance to RSV and vector SBPH was different in eight rice varieties. Some rice varieties were highly resistant to RSV and vector SBPH, such as 'IR36', 'Kasalash', 'Zhaiyeqing 8', 'Daorenqiao' and 'DV85'; some ,such as 'Aizhi97' and 'Kenta Nakan' were only resistant to RSV but susceptible to SBPH; the last one, 'IR24', was moderately resistant to RSV and SBPH. This study provides a basis for using these sources of resistance in rice breeding progress.Using Asominori (japonica) × IR24 (indica) RIL population,, one putative QTL was detected in the vicinity of XNpb257(G257) on chromosome 11 under the individual inoculation test and the field test, respectively; using a chromosome segment substitution line (CSSL) population from the same parents, one putative QTL was also mapped near XNpb257 under the field test; using IR36/Nekken2 RIL population, one putative QTL was located in the region of marker RM202-RM287 on chromosome 11 under the individual inoculation test and the mass... |
