Abstract:
【Objective】 The aim of this study was to screen sugar for resistance to pepper bacterial wilt and analyze its resistance mechanism, providing a theoretical basis for the development of control agents against pepper bacterial wilt. 【Method】 Ten sugars of sucrose, maltose, L-arabinose, D-lactose, D-raffinose, D-fructose, D-galactose, D-glucose, Dribose and D-xylose were used as experimental materials, the tested strain was
Ralstonia pseudosolanacearum RS03. Analyzed the assimilation of
R. pseudosolanacearum on sugar, seedling experiments and indoor pot experiments were conducted to screen for the sugar with the best control effect on pepper bacterial wilt. The interaction between the selected sugar and
R. pseudosolanacearum was further studied by the tests of antimicrobial activity, pathogenicity and chemotactic response. And the activities of denfense enzymes such as peroxidase(POD), phenylalanine ammonia-lyase(PAL) and polyphenol oxidase(PPO) activities in the stems of sugar-treated pepper plants were determined at 2, 4, 6, and 8 d after inoculation with
R. pseudosolanacearum. 【Result】 Among the ten sugars,
R. pseudosolanacearum showed negative assimilation to L-arabinose, D-lactose and D-raffinose, therefore they were selected for the follow-up test. The seedling test results indicated that both L-arabinose and D-raffinose significantlyreduced the incidence of pepper bacterial wilt(
P<0.05,the same below). The results of pot experiment showed that L-arabinose had the best control effect on pepper bacterial wilt, reaching 90.67%. The interaction analysis between L-arabinose and
R. pseudosolanacearum showed that Larabinose had no inhibitory effect on
R. pseudosolanacearum and no effect on its pathogenicity. Additionally,
R. pseudosolanacearum did not show chemotactic response towards L-arabinose. Defense enzyme activity tests further indicated that L-arabinose treatment could significantly increase the activities of POD, PAL, and PPO in pepper stems. The activities of POD and PPO both showed an increasing trend with the extension of inoculation time, reaching their peaks at 571.11 and 125.33 U/g after 8 d of inoculation, respectively. The PAL activity showed a fluctuating trend, reaching its peak at 24.13 U/g on the 4
th d of inoculation. 【Conclusion】 L-arabinose has the best control effect on pepper bacterial wilt.It may enhance the resistance of pepper to bacterial wilt by increasing the activity of defense enzymes within the plant, and has the potential to be developed into a new type of control agent for pepper bacterial wilt.