The evaluation for resistance to seedling damping-off caused by Aphanomyces cochlioides in sugar beet line bred in Japan
2008
Okazaki, K. (National Agricultural Research Center for Hokkaido Region (NARCH) (Japan)) | Takahashi, H. | Taguchi, K.
To initiate the breeding program for resistant cultivar to damping-off disease in sugar beet, 100 lines bred in NARCH (12 pollinator lines, 31 selfing O-type lines (hereafter SF line) and 57 self-incompatible O-type lines (SI line)) were assessed for resistance to seedling damping-off disease caused by Aphanomyces cochlioides Dreshsler under greenhouse condition. As the result, all pollinator lines were grouped as susceptible, no promising line was found. By contrast, SF lines and SI lines exhibited various degree of resistance. 5 SF lines and 6 SI lines were selected as resistant lines. To analyze the inheritance way of resistance in F1, the resistant degree of F1 hybrid that had resistant line NK-333mm-O(SI line) or NK-237BRmm-O(SF line), these line were derived from different origin, in parent were evaluated. The resistance degrees showed similar value as mid-parent in the F1 hybrid of NK-333mm-O. On the other hand, the resistance degrees were higher than these parents in the F1 hybrid of NK-237BRmm-O, and those over dominance were found to be a positive direction. Therefore it was considered for breeding resistant cultivar that the inheritance way of F1 hybrids were analyzed in more detail. 56 SF lines were assessed for resistance to root rot caused by A. cochlioides in infested field. No correlation in the resistance of damping-off and root rot was observed. It was suggested that the resistance system were different in damping-off and root rot.
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