黄萎病菌毒素粗提液对棉花抗性酶的诱导

Infection of the Verticillium dahliae Toxin Filtrate Inducing Anti-enzyme in Cotton (Gossypium hirsutum L.)

【目的】对黄萎病菌毒素滤液诱导棉花体内抗病性相关酶的研究,探索棉花黄萎病菌诱导抗性的生理机制。【方法】以4种浓度[病菌滤液原液(VD)、1﹕20、1﹕40、1﹕50]的黄萎病菌毒素液,在0、12、24、48、60、72 h预处理后,观察4～6叶龄棉苗叶和根的外部表现及发病情况,测定其植株形态的4～6片真叶萎蔫指标和体内相关抗性酶的变化。【结果】(1)不同浓度的毒素液浸泡棉根48 h后,1﹕20组,真叶萎蔫,子叶倒挂;1﹕40组,真叶轻度萎蔫,子叶萎蔫;1﹕50组,仅表现为子叶失水,1～2片真叶略显失水,大多数真叶完好;而VD对照组表现为3级危害,严重萎蔫。当毒素液浓度降至1﹕50时,预处理棉苗72 h,虽子叶下垂,但真叶完好,对照全株萎蔫;再接高浓度毒素液48 h后,子叶倒挂,真叶开始失水,但对照子叶脱落,真叶严重失水且萎蔫。总之,1﹕50组对黄萎病的抵抗力均强于1﹕20与1﹕40组的预处理。(2)1﹕50预处理组不仅能降低棉株体内有害物质MDA的含量,例如预处理12 h达最低值0.536μmol.g-1,为同时刻对照2.055μmol.g-1的24%,显著差异;同时提高了体内抗性相关酶POD活性,例如预处理72 h活性高达11.94μg.mg-1.min-1,而对照在24 h后即已检测不出POD活性。SOD的活性也呈现较高水平且一直维持在相对较高水平。例如经预处理再接高浓度毒素液72 h后,SOD活性高达12.8μg.mg-1.min-1,而对照在24 h后也检测不出SOD活性。从而缓解了黄萎病菌毒素液对棉花的侵害,提高棉花的抗病性。【结论】适宜浓度(1﹕50)的黄萎病菌毒素液可以做为生物激发子成功地诱导棉花对黄萎病的系统获得抗性。

[Objective] The objective of this study is to explore the mechanism of inducing resistance of anti-enzymes induced by toxin filtrated culture fluid to the infection of the Verticillium dahliae L. in cotton （Gossypium hirsutum L.）. [ Method ] The roots of 4-6-leaf-old seedlings were immersed in four kinds of concentrations （VD, 1 ： 20, 1 ： 40, 1 ： 50） of filtrated culture fluid （VD） as pretreatment for 0, 12, 24, 48, 60, and 72 h, respectively, and then passed to the original culture fluid （VD）, the wilting degree of the plants and related physiological parameters for anti-disease were observed and measured. [ Result] It was found that the leaves of cotton were wilted and the cotyledons were inverted because of serious wilting after immersing the roots by toxin filtrated culture fluid for 48 h in 1 ： 20 treatments, the leaves and the cotyledons were wilted normally in 1 ： 40 treatments, the majority of leaves were intact, only 1-2 leaves and cotyledons showed mild water lossing, while the leaves were seriously wilted as three class level of harm in control （VD）, i.e. undiluted toxin filtrated culture fluid. After 72 h of pretreatment with 1 ： 50 concentration, the cotyledonshowed water lossing and the leaves were intact, but the whole leaves of control （VD） were wilted. In inoculation with the undiluted toxin filtrated culture fluid for 48 h, the cotyledon inverted and the leaves started to dehydrate, but the cotyledon was failed off and the leaves showed serious water lossing and wilting. In short, the resistance to Verticillium wilt in 1 ： 50 pretreatment is stronger than that in 1 ： 20 and 1 ： 40 pretreatments. Pretreatment with toxin filtrated culture fluid at 1 ： 50 not only can reduce the MDA content of harmful substances for instance, the MDA content was 0.536μmol.g^-1 after 12 h of pretreatment, which was only 24% of 2.055 μmol.g^-1 of the control and reached to the significant difference, at the same time, the activity of enzymes related to POD in vivo was improved, for instance the POD activity was as high as 11.94μg·mg^-1 after pretreating for 72 h, in contrast, POD activity was not detected only after 24 h. The SOD activity was also showed a higher level and has been maintained for a long time, for example, the activity of SOD was up to 12.8 μg·mg^-1 after inoculating the undiluted toxin filtrated culture fluid for 72 h, but POD activity was not detected only after 24 h. [Conclusion] The suitable concentration （1 ： 50） of toxin filtrated culture fluid of Verticillium dahliae L. can be used as a biological toxin elicitor to induce the systemic resistance to Verticillium wilt in cotton.