Pathogenic characteristics by temperature of Ralstonia solanacearum phylotypes Ⅰ and Ⅳusing in vitro screening assay for resistance to bacterial wilt in potato

We examined the pathogenic differences between Ralstonia solanacearum phylotypes I and IV. R. solanacearum phylotypes I （MAFF327001） and IV （MAFF327032） were inoculated to potato using an in vitro screening assay at 22, 24, 26 and 28℃ incubation temperatures after inoculation. As a result, phylotype IV showed high pathogenicity for potato at a lower temperature than phylotype I. The most suitable temperature for evaluating the degree of resistance in potato cultivars and breeding lines was clearly different between phylotypes Ⅰand Ⅳ, with phylotype Ⅰat 28℃，and phylotype Ⅳ at 26℃. However, the degree of resistance in potato cultivars and breeding lines for both phylotypes had a similar tendency at the most suitable temperature conditions. In conclusion, phylotype IV showed pathogenicity at a lower temperature than phylotype Ⅰ, but the results suggested resistance was shown in the potato cultivars and breeding lines regardless of the phylotype（Ⅰ and Ⅳ）.