抗辣椒青枯病的糖类筛选及抗性机制研究

Screening of sugar for resistance to pepper bacterial wilt and its resistance mechanism

  • 摘要: 【目的】 筛选抗辣椒青枯病的糖类,并分析其抗性机制,为辣椒青枯病防治药剂的开发提供理论依据。【方法】 以蔗糖、麦芽糖、L-阿拉伯糖、D-乳糖、D-棉子糖、D-果糖、D-半乳糖、D-葡萄糖、D-核糖和D-木糖10种糖为试验材料,供试菌株为假茄科雷尔氏菌(Ralstonia pseudosolanacearum)RS03,分析青枯菌对糖的同化作用,采用幼苗试验和室内盆栽试验筛选对辣椒青枯病防治效果最佳的糖。通过抗菌活性、致病性和趋化性测定分析糖与青枯菌的相互作用;接种青枯菌后第2、4、6和8 d,测定经糖处理的辣椒茎部过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)等防御酶活性。【结果】 10种糖中,L-阿拉伯糖、D-乳糖和D-棉子糖不被青枯菌同化,选择其进行后续试验;幼苗试验结果表明,L-阿拉伯糖和D-棉子糖均显著降低辣椒青枯病的发病率(P<0.05,下同);室内盆栽试验结果表明,L-阿拉伯糖对辣椒青枯病的防治效果最佳,达90.67%。分析L-阿拉伯糖与青枯菌的相互作用,结果表明,L-阿拉伯糖对青枯菌无抑菌作用且对其致病性没有影响,青枯菌对L-阿拉伯糖无趋化性。防御酶活性检测结果表明,L-阿拉伯糖处理能显著提高辣椒茎部POD、PAL和PPO活性,POD和PPO活性均随着青枯菌接种时间的推移呈增长趋势,在接种8 d后达峰值,分别为571.11和125.33 U/g;而PAL活性呈波动变化趋势,接种后第4 d达峰值,为24.13 U/g。【结论】 L-阿拉伯糖对辣椒青枯病的防治效果最佳,其能通过提高植株体内防御酶活性来增强辣椒对青枯病的抗性,具有开发成新型辣椒青枯病防治药剂的潜力。

     

    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 4th 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.

     

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