Dynamic QTL analysis for rice blast resistance under natural infection conditions

Dynamic analyses of rice blast resistance for the assessment of genetic and environmental effects were characterized employing a recombinant inbred lines (RILs) population. The study was conducted at three different developmental stages of rice using natural infection tests in two years. The number of main-effect quantitative trait loci (QTL), epistatic QTL and their environmental interactions greatly differed across various measuring stages. Two major QTL (r11a and r11b) both on chromosome 11 could be detected at all stages, whereas most QTL were identified only at one or two stages in the population. It was suggested that the unstable activities of most QTL identified for blast resistance may well be due to effects of major QTL, epistatic effects between different loci, the developmental status of rice, and the environments in which they were grown. Comparison of QTL analysis conducted under the conditions of natural infection and artificial inoculation was performed and drew a new conclusion that QTL analysis of plant resistance based on natural infection would have more advantages than that based on artificial inoculation.