Integrative Research On Pathogen Of Fusarium Wilts And Population Structure Of Resistant Germplasm In Cabbage

The fusarium wilts, also named cabbage yellows, caused by the soilborne fungus Fusarium oxysporum f. sp. conglutinans (FOC), is one of the most serious soilborne cabbage diseases in China. It first broke out in 2001 in Beijing, spread rapidly, and became serious in most of the warm season-grown cabbage fields in Northern region of China including Beijing, Shanxi province. The use of resistant varieties is the only control. However, most of the commercial cabbage varieties are fusarium wilt susceptible because the disease resistant breeding programs have still not been launched in China.We collected diseased plants from Beijing and Shanxi province. then separated, purified and identified pathogenic bacteria GLHW1 and GLHWY and non-pathogenic GLHW2 and GLHW4. Through analysis based on morphology of fungal and AFLP of cloning of two kinds of pathogenic fusarium, the results indicated that the two fusarium isolates showed high indentity. Whereas it has some discrepancies in pathogenicity and morphology as well as molecular level.We finally established inoculation process for resistance evaluation of cabbage wilt disease. Process is as follows: you can use root-dip inoculation at seedling age of 3-true-leaves by soaking root in spore suspension of 1×106 per ml for 15 minutes. For the sake of labour-saving, you can use root-pour inoculation, and the emphasis is make the root wound intentional in order to accelerate infection, you should employ 1×107 or even more high concentration to ensure sufficient amount of pathogen.87 cabbage breeding material reserved in Beijing Vegetable Research Center (BVRC) were inoculated with GLHW1 for evaluation of fusarium wilt resisitance. The study here found that 36 material show high resistance (HR) , 27 show high susceptibility (HS). In addition, show resisitance (R), moderate resistance(MR) and moderate susceptibility (MS) sum to 24, and these material did not show resistance reaction with quantitative trait characteristic. According to analysis of agronomic traits and resistance evaluation, we found that there was no remarkable correlation between agronomic diversity and fusarium wilt of cabbage. F2 individuals showed a segregation ratio of 3 :1. The results indicated that the resisitance of fusarium wilt in cabbage is controlled by a single dominant gene.Association analysis is a novel method for gene mapping with the superiority of using natural population for gene mapping. 67 core germplasm resources of cabbage breeding materials were used for association analysis, we obtained 7 AFLP markers associated with resistance of fusarium wilt, especially, association degree with resisitance of E36M54-4 and E36M54-15 achieve extremely significance level (P<0.01)...