不同苦瓜品系的抗白粉病能力及其与防御酶活性的相关性

Correlation of Bitter Melon's Resistance to Powdery Mildew and Activities of Defense Enzymes

为筛选抗白粉病的苦瓜种质开展抗病育种,探讨苦瓜抗白粉病的生理生化机制,以21份来源不同的苦瓜种质资源为试材,连续2年鉴定白粉病抗病性,并从中选出4份抗性不同的材料,分别测定接种白粉病菌前及接种后不同时期的5种防御酶活性,结合病情指数做一元线性相关分析,研究防御酶的动态变化与白粉病抗性之间的关系。结果表明:不同来源的苦瓜品系之间白粉病发病程度表现出较大的差异和多样性,28.57%的苦瓜种质资源表现为抗病,28.57%表现为中抗,33.33%表现为感病,9.53%表现为高感;健康植株的过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)5种防御酶活性差异不大,接种白粉病菌后,抗感品系植株体内除CAT外,各种酶的活性均升高,抗病品系的酶活及酶活增幅高于或显著高于感病品系,抗病品系在接种白粉病菌后的第10天POD和PAL活性最高,PPO在接种后第5天活性最高,感病和高感品系则一直保持较低的酶活性,因此POD、PAL和PPO可以作为衡量苦瓜抗白粉病的指标;相关分析表明,5种酶的酶活和酶活增幅均与病情指数呈负相关或显著负相关关系,说明酶活或酶活增幅越高,抗病性越强。

For selecting the bitter melon germplasm resource in disease resistant breeding, the physiological and biochemical mechanism of bitter melon's resistance to powdery mildew. Four materials with different resistances to powdery mildew were chosen from 21 bitter melon germplasms from different origins according to two consecutive years' identification of resistance to powdery mildew. Five defense enzymes activities were measured respectively in different periods before and post-inoculation and a simple linear regression analysis associated with the disease index was made to study the relationship between the dynamic change of defense enzyme activities and the resistance to powdery mildew. The results showed: The powdery mildew morbidity degree of bitter melon germplasms from different sources showed greater difference and diversity, 28.57% resistant, 28.57%moderate resistance, 33.33% susceptible and 9.53% more susceptible. The difference of peroxidase(POD), superoxide dismutase(SOD), catalase(CAT), phenylalanine ammonia lyase(PAL) and polyphenol oxidase(PPO) activities among resistant varieties was not significant, the activities of different enzymes of resistant varieties were higher than those of control and the susceptible varieties after inoculated with powdery mildew. The activities of PPO of resistant strains appeared peak at 5d after inoculation, the peak for POD and PAL was 10 d after inoculation; the enzyme activity of susceptible and highly susceptible strains remained low,therefore the activities of POD, PAL, and PPO could be used as indicators of bitter gourd resistance to powdery mildew. Theresults revealed that the higher enzyme activities and the increase rate of activities, the stronger resistance to powdery mildew,therefore they could be used as the references in identification of the bitter melon germplasm resistance to powdery mildew.