大豆品种Maple Arrow耐菌核病生化机制

Biochemical resistance mechanism of soybean cultivar Maple Arrow to Sclerotinia sclerotiorum

以世界公认的菌核病抗性品种Maple Arrow以及感病品种合丰25为材料,在大豆V1期进行活体接种,比较不同抗感材料在接种核盘菌后的72h内6个时间点的菌丝扩展速度和4种生化酶活性,旨在明确MapleArrow抗菌核病的生化机制,为抗病育种提供依据.扫描电镜结果表明,抗感品种在侵染后0～72h对病原菌的抗性差异明显,接种前期病原菌在Maple Arrow叶片上的扩展速度明显低于合丰25.接种后期,Maple Arrow叶片病健交界明显,菌丝体周围寄主组织结构保持相对完整;合丰25叶片布满菌丝体,叶片结构崩溃.动态生化指标测定结果表明抗感品种在过氧化物酶（POD）、多酚氧化酶（PPO）、超氧化物歧化酶（SOD）和苯丙氨酸解氨酶（PAL）活性均不同程度的高于对照组.接种后24h Maple Arrow的PPO活性显著高于感病品种;接种后48h Maple Arrow的POD和PAL的活性增加幅度显著高于合丰25.由此得出结论,抗病品种Maple Arrow的保护酶系统对核盘菌侵染的响应比感病品种合丰25更为活跃,四种保护酶中的PPO、POD和PAL是两种抗性差异的关键因子,其中PPO主要作用于感染前期,POD和PAL主要作用于后期.

To clarify the biochemical mechanism of Sclerotinia sclerotiorum disease- resistance of Maple Arrow,a resistant cultivar to S. sclerotiorum,mycelia growth rate on leaf and protective enzyme changes were investigated in2 soybean cultivars Hefeng 25( susceptible) and Maple Arrow at 0- 72 h post inoculation. Results showed that leaf tissue of the cultivars had significant divergence at 0- 72 h after inoculated by S. sclerotiorum. Mycelium growth rate on leaves of Maple Arrow was significantly lower at preliminary stages of infection. At the later periods of infection,leaf structures of Maple Arrow was relatively integrated,but Hefeng 25 leaves were covered with mycelium,and the leaf structure collapsed. The activity of peroxidase( POD),polyphenol oxidase( PPO),superoxide dismutase( SOD) and phenylalanine ammonia lyase( PAL) were tested in inoculated and non- inoculated leaves at 6 time points post inoculation. Results showed that the activity of the 4 protective enzymes in resistant cultivar were higher than that in susceptible cultivar in different degrees. PPO activity in Maple Arrow was significantly higher at 24hpi;POD and PAL activity in inoculated Maple Arrow was increased and significantly higher than that in inoculated Hefeng 25 after 48 hpi. In summary the protective enzyme system of the resistant cultivars Maple Arrow was more active than Hefeng 25 in response to infection. The PPO,POD and PAL might have played key roles in resistance of Maple Arrow,PPO mainly worked at preliminary stage of infection,POD and PAL mainly worked at the middle and later periods of infection.