Mapping The QTLs Of Rice Bacterial Leaf Streak With SSR Markers

Bacterial leaf streak (BLS), caused by the pathogen Xanthomonas oryzae pv.oryzicola is a familiar epidemic disease in rice in South China. In recent years, it has become the fourth devastating disease in rice after blast, bacterial leaf blight and sheath blight disease in china and is strictly controlled by China quarantine regulation. According to the research of the pioneers, Resistance to BLS in rice was a quantitative trait, which controlled by a few minor genes. Exploiting the resistant genes and developping resistant varieties has been improved to be the most effective way to control BLS in rice.DV85 and IR24 are two indica rice varieties, which are highly resistance andhighly susceptible to BLS respectively. In this study, we evaluated the BLS resistance(2004 for F₂ population, 2005 for F₃ lines) of rice and analyzed the QTLs for BLSresistance, using a F₂ population and a F₃ line which comes from some (100) of the F₂individuals. The F₂ population derived from the cross between DV85 and IR24, and itconsisted of 246 individuals. The main results are summarized as follows:1 According to the resistance evaluation result, the reaction of different parents topathogen inoculation was significantly different in the same years, while theevaluation result of the same parent is generally the same in different years. Theresistant parent (DV85) was highly resistant in both years (2004 and 2005), thelesion length was 0.33 cm and 0.47 cm respectively, while the susceptible parent(IR24) was highly susceptible, whose lesion length was 3.74 cm and 3.32 cmresceptively.Besides, the results also indicated that the reaction of the plants to pathogen inoculation was generally consistent in different populations. In both population, the streak lesion length data continuously distributed (Fig.1), and the mean lesion length was 1.80 cm in F₂ population in 2004 while it was 1.64 cm in F₃ population in 2005. The skewness of the distribution was 0.783 in F₂ population and 0.659 in F₃ population.2 A total of 112 SSR makers which was polymorphism in parents were used to constructed molecular map. A map with 98 SSR markers covering a length of 1164.1 cM was constructed based on the F₂ population; the interval between two makers was 11.9 cM average.3 Based on the resistance evaluation and the molecular map constructed above, 6 QTLs for BLS resistance were detected on chromosome 5 and 7 in this study. Two...