外源SA影响油菜叶表皮蜡质及菌核病抗性的机制

Effects of SA Induction on Leaf Cuticular Wax and Resistance to Sclerotinia sclerotiorurn in Brassica napus

处于植物地上部分最外层的表皮蜡质被认为是植物抵御病原物入侵的第一道屏障,但表皮蜡质是否及如何参与油菜菌核病防御机制还不清楚。本试验选用2个抗病性不同的油菜品种中双9号(抗性品种)和渝油19(感病品种),对水杨酸(SA)处理后的油菜幼苗接种核盘菌,分析油菜病情指数、叶表皮蜡质含量和晶体结构特征、抗氧化酶活性的变化规律。结果表明,SA处理使中双9号病情指数显著下降,渝油19无显著变化,SA诱导了油菜抗性品种中双9号对菌核病的抗性。接种核盘菌后,中双9号PAL活性显著增加,而渝油19显著下降;SA处理植株叶片PAL和POD活性显著高于单纯接种植株。渝油19苗期叶表皮蜡质总量显著高于中双9号。SA诱导中双9号蜡质总量及组分含量增加,柱状晶体结构减少,片状结构增加,扩大了蜡质层覆盖叶表面积。渝油19在SA处理后蜡质含量无显著变化,晶体结构发生了与中双9号相似的变化,但渝油19蜡质晶体熔融后覆盖叶表面积小于中双9号。综合分析认为防御酶活性及叶表皮蜡质共同参与SA诱导中双9号抗性增强的过程。

Cuticular wax on the surfaces of higher plants is believed to be the initial defense system to various pathogens. How- ever, whether or how wax deposition in Brassica napus is involved in the resistant mechanism of infecting Sclerotinia scle- rotiorum, is still unclear. In the current experiment, two Brassica napus cultivars with different disease resistances, Zhongshuang 9 （resistant） and Yuyou 19 （susceptible）, were selected to analyze the dynamics of disease indices, contents and crystal structure of leaf cuticular wax, activities of defense enzymes, and gas exchange indices under the conditions of SA induction and Sclerotinia sclerotiorurn inoculation. The results showed that SA induction significantly reduced the disease index of Zhongshuang 9, in- creased its resistance, while SA had no significant influence on disease index of Yuyou 19. When the plants were inoculated with S. sclerotiorurn, the activity of PAL in leaf of Zhongshuang 9 increased while that of Yuyou 19 decreased. The activities of PAL and POD in plants with SA induction were significantly higher than those in plants treated with only S. sclerotiorurn inoculation for both cultivars. The content of total wax in leaf of Zhongshuang 9 was significantly lower than that of Yuyou 19. SA induction increased the contents of total wax and wax constituents for Zhongshuang 9, reduced the amounts of rod crystalloid and increased the amounts of plate crystalloid, and increased the leaf area covered with waxes. The contents of waxes for Yuyou 19 were changed insignificantly by SA induction. However, the changes of the wax crystaUoid structure of Yuyou 19 by SA induction were similar with those of Zhongshuang 9, except for a lower leaf area covered with waxes. Conclusion is that both defense enzymes and leaf cuticular waxes are involved in the process of increasing resistance induced by SA for resistant cultivar Zhongshuang 9.