【作者】 李萌；

【导师】 侯明生；

【作者基本信息】 华中农业大学 ， 植物病理学， 2009， 硕士

【摘要】 水稻稻瘟病(Magnaporthe grisea Sacc.)是水稻三大病害中流行情况最复杂、潜在威胁最大的病害,对稻谷产量和品质影响都非常大。目前认为最有效的的防治方法是培育抗病品种,但是由于其生理小种变异较快,运用传统的育种方法不能满足生产的需求,而利用稻瘟菌粗毒素作为选择压的突变体筛选法具有很好的发展前景。本文参照刘文萍等人的方法提取稻瘟菌粗毒素,测定粗毒素对水稻和大麦种子萌发和根系生长的影响,在此基础上对粗毒素理化性质及其对水稻叶片叶绿素含量和防御酶活性的影响进行初步研究,同时在室内测定了几种化学药剂对稻瘟菌的抑制效果。研究结果为了解稻瘟菌的致病机理及水稻抗病育种奠定基础。论文主要结果如下:1.稻瘟菌粗毒素相关理化特性研究表明:稻瘟菌粗毒素对水稻和大麦种子萌发和根系生长具有显著的抑制作用,并且浓度越高抑制作用越强。其中对种子萌发的抑制率达到83%以上,对根系生长的抑制率达到89%。进一步对其相关特性进行测定表明稻瘟菌粗毒素有效成分主要为蛋白质,蛋白质含量达68.35 ug/ml,且该粗毒素是一种酸碱稳定性较高,耐热性、紫外线稳定性较强的物质。2.不同培养条件对稻瘟菌产毒素能力的影响研究结果表明:培养7d、培养基pH6.5且在光照交替条件下最有利于稻瘟菌毒素的产生,而对毒素的产生最有利的C源为葡萄糖和蔗糖,最有利的N源为硝酸铵。3.稻瘟菌粗毒素对水稻叶绿素含量的影响研究结果表明:稻瘟菌粗毒素对水稻叶片叶绿素有很大破坏作用或对叶绿素的合成有明显抑制作用。将粗毒素稀释2倍,与水稻叶片共培养48 h后,叶片叶绿素含量比对照减少85%以上,并且毒素浓度越高,处理时间越长,水稻叶绿素含量越低。4.稻瘟菌粗毒素对几种防御酶活性的影响研究结果表明:稻瘟菌粗毒素对水稻叶片体内多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)和超歧氧化物酶(SOD)等寄主防御酶活性都有一定的促进作用。当粗毒素稀释2-4倍时,POD、PPO、PAL、SOD酶活性均明显高于对照;当稀释8倍时,这些酶的活性则变化很小,说明毒素含量比较低的时候对酶活性的影响也较小。防御酶的活性与毒素处理的时间密切相关,通常随着处理时间的延长,酶活性不断升高;毒素处理36-72 h后,酶活性达最高值,抗病品种中几种防御酶的活性均高于感病品种。5.室内测定不同化学药剂对稻瘟菌毒力的抑制效果表明:稻病一次清、春雷霉素的抑菌效果最好,对菌丝生长的相对抑制率为分别为14.07%-89.07%和17.99%-88.45%,其次为5%瘟枯病杀和稻病康,多菌灵抑菌效果最差。更多还原

【Abstract】 Rice blast (Magnaporthe grisea Sacc) are the three major diseases of rice in the prevalence of the most complex, the biggest potential threat to the diseases, the impact on rice yield and quality are very great. At present, the most effective prevention method is cultivate disease-resistant varieties. However, due to its relatively rapid physiological variations, using traditional breeding methods can not meet the production requirements. The use of Magnaporthe grisea Crude toxins for the selection of mutants pressure screening applications has great potential and prospects for development. In this paper, reference method of Liu WenPing to extract the crude toxin of rice blast fungus, crude toxin was determined on rice and barley seed germination and root growth. On the basis, the physical and chemical properties of the crude toxin and its impact on Magnaporthe grisea crude toxin on the chlorophyll content of rice and rice defense enzyme activity for a preliminary study, simultaneous determination of several chemical agents on the virulence of pathogenic effects. The findings lay the foundation for understand the results of the pathogenicity of Magnaporthe grisea and rice breeding .The main findings are as follows:1.The relevant characteristics of Crude toxin showed that: the crude toxin of Magnaporthe grisea to rice and barley seed germination and root growth are significantly inhibited, and the higher the concentration, the stronger the inhibition. Which inhibit seed germination rate of more than 83% , and root growth inhibition reached 89%. Further determination of its relevant characteristics of the crude toxin of Magnaporthe grisea showed that the main active ingredient for the toxin is protein, and its content is 68.35 ug / ml. Further study of its physical and chemical properties .The results showed that the rice blast fungus toxin is a material of higher pH stability, thermal stability and strong ultraviolet stability.2. Different conditions on the rice blast fungus in the impact of crude toxin production results show that: the number of days training 7d, pH6.5, alternating light most favorable to rice blast fungus producing crude toxin. The most favorable C source is glucose and sucrose, the most favorable N source is the Ammonium nitrate.3. Magnaporthe grisea on rice chlorophyll crude toxin and the effects of several defense enzymes results show that: The crude toxin of Magnaporthe grisea have obvious damage to rice leaves. In addition, the crude toxin could significantly interfere with the chlorophyll synthesis. Dilutes 2 times the thick toxin, and the rice leaves 48 h after co-culture, the chlorophyll cotent in the rice plants was reduced by over 85%. The higher the toxin concentration was and the longer the treatment time was, the lower the chlorophyll cotent was.4 .After the treatment of Magnaporthe grisea crude toxin, the activity of defensive enzymes such as polyphenol oxidase (POD), peroxidase (POD), phenylalanie ammonialyase (PAL) and superoxide dismutase (SOD) in rice leaves was stimulated to some intension. When rice plants were treated with the crude toxin diluted 2 to 4 times, the activity of these enzymes were significantly increased, while treated with the crude toxin diluted 8 times, the enzyme activity was little changed. It noted when relatively low toxin content the impact of the activity are also less. Defense enzymes and toxins are closely related to the processing time . Also, the results showed that the higher the toxin concentration was and the longer the treatment time was, the higher the enzyme activity in rice plants was. When treated with the crude toxin for 36 to 60 hours, the enzyme activity reached the maximum, the resistant varieties enhance fast than Susceptible varieties.5 .Different chemicals on the rice blast fungus Toxicity results showed that: The inhibitory effect of daobingyiciqing and adriamycin is best. Average Inhibition of mycelial growth rate are 14.07%-89.07% and 17.99%-88.45%, Followed by are 5% wenkubisha and daobingkang, the worst inhibited effects is carbendazim.更多还原