Resistance of Commercial Radish Cultivars to Isolates of Fusarium oxysporum f. sp. raphani

摘要

Fusarium wilt of radish caused by Fusarium oxysporum f. sp. raphani (FOR) is one of the most severe diseases in radish cultivation. To define resistance characteristics of radish cultivars to FOR, we tested virulence of 8 FOR isolates in a susceptible cultivar of radish, 'Backchun'. Area under disease progress curve (AUDPC) of Fusarium wilt on the cultivar caused by FOR 60A, 59A, 57A, 147A, KR1, NW1, HN and JHW was 6.7, 14, 16, 27, 27, 30, 35 and 35, respectively. Thus, virulence of FOR HN and JHW was the strongest, followed by FOR NW1, KR1, 147A, 57A, 59A and 60A isolates. In addition, we investigated development of Fusarium wilt on 60 commercial radish cultivars caused by FOR KR1, a medium virulent isolate of them. From the results, 25 radish cultivars were selected for further study. When the cultivars were inoculated with the seven FOR isolates except for KR1, mean disease index of the cultivars by FOR 60A, 59A, 57A, 147A, NW1, HN, and JHW isolates were 0.5, 0.7, 1.2, 2.3, 2.8, 3.7 and 3.9, respectively. And the number of resistant radish cultivars to FOR 60A, 59A, 57A, 147A, NW1, HN, and JHW were 21, 20, 13, 7, 2, 1 and 1, respectively. Furthermore, development of Fusarium wilt in each cultivar was positively correlated with the virulence of FOR isolates. Taken together, these results suggest that resistance of radish to FOR isolates is likely affected by the virulence, but not resulted from race differentiation.