Molecular Mapping Of A New Bacterial Blight Resistance Gene Xa30(t) In Rice

Bacterial blight is a vascular bundle disease caused by Xanthomonas oryzaepv. Oryzae and is one of the most devastating diseases prevalent in rice producing area worldwide. Bacterial blight bring severe yield loss every year. Planting of resistant species proved to be an economical and effective way to control the disease in virtue of host resistance, and meet the needs of environment protection and sustaining development of modern agriculture as well.Despite the discovery of more than 30 resistant genes up to now, few of them had been put into use. And two of the widely used gene Xa3 and Xa4 had lost resistance in many areas. So, breeders bend themselves to mining new resistant resource, apply new elite resistant genes to improve the resistance of rice. Wild rice is a reservoir of many elite genes that absent in cultivated rice. Xa21 gene from Oryzae longistaminata and Xa23 gene from Oryzae rufipogon are two excellent genes have wide resistant spectrum and having been put into practice.Wang et al., found a germplasm displayed distinctive resistance to bacterial blight during the evaluation of bacterial blight resistance of wild rice and identified a newresistant gene systematically. It has been introgressed into Jingang 30--one of the widelyused susceptible indica cultivar in China and cultivated near-isogenic line use JG30 as recurrent parent, and Y238, the donor. BC₆F₃ generation has obtained in year 2006. The near-isogenic line is nominated as CBB30 and the resistance locus designated as Xa30(t) tentatively.Four lines of BC₆F₂ and BC₅F₂ generations of JG30/Y238 were used for molecular mapping of Xa30(t) in this study. Inoculation test of them were carried out at seedling stage and adult stage separately with the Philippine strain PXO99. The segregation ratios of the two lines BC₆F₂-3051and BC₆F₂-3047 between resistant and susceptible plants fit to 3:1 at adult stage; while segregation ratios of BC₆F₂-3045 and BC₅F₂-3027 fit to 3:1 at both stage, so we divided them into two groups temporary. 11 markers including RM1341,V88, C189,03STS, Lj74/Y02W1R,A83B4,V65,V83,V54, V37 and V78 displayed polymorphism between S-p and R-p were detected. The resistance gene of line BC₆F₂ -3051and BC₆F₂-3047 was mapped on long arm of chromosome 11 near 03STS,...