【作者】 蔚丽珍；

【导师】 张鲁刚；

【作者基本信息】 西北农林科技大学 ， 蔬菜学， 2009， 硕士

【摘要】 十字花科蔬菜的黑腐病（crucifers black rot）是由野油菜黄单胞杆菌野油菜致病变种〔Xanthomonas campestris pv. campestris （Pam.） Dowson〕引起的世界性的重要病害之一。本试验从生理学和细胞学基础的层次上,以不同抗性的大白菜品种为材料,系统研究了以下几点:1.抗氧化酶与抗病性的相关性:利用DPS数据处理系统所做的线性回归分析,对接种黑腐病处理后,每次取样的保护酶活性与病情指数之间的相关性分析结果表明,接菌后的12h和156h,SOD酶活与病情指数之间存在显著相关关系;接菌后36h,POD酶活与病情指数存在极显著相关关系;接种前后,CAT酶活于病情指数之间无显著相关。表明SOD和POD酶活可以作为大白菜与黑腐病互作中抗病性鉴定指标,而CAT酶活与大白菜黑腐病互作中抗病性不是很明显。2.抗氧化酶系统的反应:通过测定不同抗性的大白菜幼苗侵染强致病性黑腐病菌YL-17后叶片内O₂^-·和MDA含量以及SOD、POD、CAT活性,结果表明:a.当黑腐病菌侵染材料后,O₂^-·经过一个较低的水平后于36h后迅速上升,且抗感材料变化趋势相同,由此表明,无论抗性还是感性材料它们对病害的响应是相同的,只是在程度方面存在差异。在病原菌入侵过程中,由于植株本身的抗性反应,要消耗一定的O₂^-·而诱导其增加,即到开始出现症状时O₂^-·的产生速率直线增加,以诱导植保素的积累。总之,抗病品种秦白2号的O₂^-·总是高于感病品种06J31,进一步印证了O₂^-·在一定的范围内对于提高植物的抗性是有利的。b.当黑腐病菌侵染材料后,细胞膜脂过氧化作用增强,膜透性增加,加剧植物的氧化损伤,侵染黑腐病菌后感病品种MDA含量要明显高于抗病品种,表明MDA含量与抗性呈负相关。c. POD活性同时受组织衰老和病原物侵染的影响,而抗病品种受病原物侵染的影响较小,感病品种受病原物侵染的影响较大且呈明显升高的趋势,说明POD活性与抗病性成负相关。SOD活性在抗病品种上呈先升高后快速下降的趋势,而感病品种则呈下降—升高—下降特点,说明抗病品种对病原菌感染反应早,保持一定时间高水平的SOD活性可起到延迟发病的效果;而感病品种一开始防御系统薄弱,SOD活性下降,随后SOD活性应激升高短暂时间后,防御系统破坏,SOD活性下降。说明SOD活性与抗病性成正相关。CAT活性变化与寄主的发病表现存在着较大的差异,故CAT与抗病性的相关程度无法确定,有待进一步研究。3.细胞学结构变化:黑腐病原菌YL-17菌种侵染大白菜幼苗叶片后,大白菜幼苗叶肉细胞变大,细胞数目变少,细胞排列逐渐疏松,尤其是栅栏组织,叶绿体由原来的贴壁分布变为混乱分布,且数量逐渐变少;叶绿体基粒片层从膨胀到紊乱,叶绿体膜从模糊到破裂,直到类囊体和基质外渗,出现空泡化,线粒体膜破裂,最后细胞器解体;抗病品种秦白2号与感病品种06J31相比具有整齐、紧密的多层栅栏组织,受到破坏程度也就更轻。更多还原

【Abstract】 Crucifers black rot was one of the most important diseases caused by Xanthomonas campestris pv. campestris （Pam.） Dowson in the world. This experiment, choosing Chinese cabbage with different disease resistance as matertials, systematically made a reaearch on the physiological and eytological changes. And the results were as follows:1. The correlation between antioxidant enzymes and disease resistanceUsing DPS data processing system to make linear regression analysis, after inoculated the objects with crucifers black rot, a research was made to find out the correlation between protective enzyme activity and disease index in each time. The results showed that, there existed a significant correlation between SOD activity and disease index after inoculated 12 hours and 156 hours; there existed a significant correlation between POD activity and disease index after inoculated 36 hours; there existed no significant correlation between CAT activity and disease index before and after inoculation. It demonstrated that SOD and POD activity could be the indexes of resistance identification in the interaction between Chinese cabbage and crucifers black rot, while CAT activity were not significantly correlated with the disease resistance.2. The reaction of antioxidant enzyme systemLeaf O₂^-·content, MDA content, SOD activity, POD activity, and CAT activity were tested when the Chinese cabbage with different resistant were inoculated with strong pathogenicity YL-17. The results were as follow:a. After inoculated with crucifers black rot, the O₂^-·content of resistant or susceptible cabbage had similar trend, rose in 36 hours, and before that, kept in a lower level. It demonstrated that both kinds of materials had the same response to the disease, but existed difference at reaction intensity. In the process of inoculation, the O₂^-·was consumed firstly, and then increased because of the resistant reaction by itself. That was, at the time of occuring symptoms, producing ratio of O₂^-·showed linear increase to induce phytoalexin accumulation. In short, O₂^-·content of resistant species Qinbai No.2 was higher than that of susceptible ones, which demonstrated that it was beneficial to accumulate O₂^-·to some extence to raise resistance. b. After inoculated with crucifers black rot, membrane lipid peroxidation aggravated with increasing membrane permeability and oxidative damage. The MDA content of susceptible species was more than that of resistant species, which demonstrated that the MDA content showed negative correlation with resistance.c. POD activity was affected by issue senescence and pathogen infection, however, resistant species had litlle effection, and susceptible ones were opposite with a rising trend, which demonstrated that POD activity negatively correlated to resistance. The changing trend of SOD activity in resistant species was up first, and then down sharply, while down-up-down trand occurred in susceptible species, which demonstrated that resistant species gave a quick reaction to pathogen infection, and kept high level of SOD activity to delay disease course, while for fragile defense system in susceptible species, SOD activity decreased at first, and then rose for a while, decreased sharply with destroyed defense system. In short, SOD activity showed positive correlation with resistance. The correlation of CAT activity and resistance could not be determined because great difference existed between CAT activity changes and disease severity, so it needed further research.3. Changes of cytological structureAfter inoculated Chinese cabbage seedlings with pathogen YL-17, its leaf showed larger mesophyll cells, less cell number, looser cell arrangement especially for palisade tissur. Chloroplasts distribution showed disorder spread from adherent cell, and the number decreased. Grana lamella of chloroplasts changed from expension to disorder, chloroplast membrane changed from fuzziness to rupture, and then thylakoid and matrix exosmosed, vacuolization appeared. Mitochondrial membrane broke, organelles disintegrated finally. The resistant species Qinbai No.2 was less damaged because of regular, tight and multi-layer palisade tissue compared with susceptible species 06J31.更多还原