不同毒性玉米大斑病菌侵染对感病玉米叶片PAL活性的影响

Effects of Infection with Different Virulent Isolates of Setosphaeria turcica on PAL Activity of Susceptible Corn Leaves

利用从自然界中分离纯化的156株玉米大斑病菌菌株中筛选得到的强毒菌株YC和弱毒菌株01—23T分别接种感病玉米叶片，测定玉米叶片苯丙氨酸解氨酶（PAL）活性的动态变化。结果表明，与不接种对照相比，接种强毒菌株YC1～2d时，玉米叶片PAL活性显著降低；接种3～4d时，PAL活性略有上升但差异不显著；接种5d时，PAL活性又显著降低。接种弱毒菌株01-23T1-2d时，玉米叶片PAL活性略有降低但差异不显著，接种3～5d时，PAL活性上升但差异仍不显著。PAL是玉米抵抗玉米大斑病的一种重要防御酶，在侵染初期，只有降低玉米叶片的PAL活性玉米大斑病菌才能达到成功定殖的目的，可为明确玉米大斑病菌致病性的生化机制提供一定理论依据。

Screened from 156 natural isolates of Setosphaeria turcica, the hyper-virulent isolate YC and ny- po-virulent isolate 01-23T were inoculated onto susceptible corn leaves and the dynamics of phenylalanine ammonia lyase（PAL） activity in corn leaves were analyzed. The results showed that compared to un-inoculated corn leaves（CK）, the PAL activity decreased significantly after 1-2 days, increased non-significantly after 3-4 days, and decreased significantly after 5 days when inoculated by hyper-virulent isolate YC. However, PAL activity decreased non-signifi- cantly after 1-2 days and increased non-significantly after 3-5 days when inoculated by hypo-virulent isolate 01-23T. The results showed that PAL was an important defense enzyme for maize to resist Northern Corn Leaf Blight, and the pathogen could successfully colonize in corn leaves only by reducing PAL activity in early infection stage. The results will provide the basis for clarifying the biochemical mechanisms of the pathogenicity in Setosphaeria turcica.