玉米纹枯病生防菌DZSY21的抗病机制

Resistance mechanism of bio-control strain DZSY21 against maize sheath blight

为明确杜仲内生细菌DZSY21对玉米纹枯病的抗病机制,利用抗生素标记法分析了DZSY21菌体在玉米叶鞘组织中的定殖情况,通过小区接种试验,研究不同生育期玉米叶鞘引入DZSY21对玉米抗纹枯病的作用,并采用分光光度法和荧光定量PCR技术检测不同生育期玉米叶鞘组织中的多酚氧化酶(PPO)、过氧化物酶(POD)和苯丙氨酸解氨酶(PAL)的酶活性以及PR-1、PR-2a基因的表达水平变化。结果表明:菌株DZSY21引入玉米叶鞘后,可在其体内定殖,与玉米叶鞘组织形成和谐的共生关系,在一定程度上增强玉米对纹枯病的抗性;DZSY21在玉米叶鞘的定殖能提高玉米叶鞘组织防御酶PPO、POD和PAL的活性,同时诱导防卫基因表达。该研究结果为揭示生防细菌DZSY21的生防机理及应用提供了科学依据。

This study was carried out to explicit the resistance mechanism of endophytic bacteria DZSY21 against maize sheath blight. The colonization property of biocontrol strain DZSY21 in maize leaf sheath was analysed by antibiotic label method,and resistance of maize treated with DZSY21 at different growth stages to sheath blight were assessed through field experiments,then the related enzymes activity and expression of PR-1 and PR-2a gene in maize leaf sheath treated with DZSY21 at different growth stages were detected by spectrophotometry and quantitative realtime PCR. The results indicated that DZSY21 could successfully colonize maize leaf sheath,it had a symbiotic relationship with maize leaf sheath,and colonization of DZSY21 in maize leaf sheath could significantly enhance maize resistance to maize sheath blight. Activities of polyphenol oxidase（PPO）,peroxidase（POD）,phenylalnine ammonialyase（PAL） and expression of defense response genes（PR-1,PR-2a） in maize leaf sheath treated with DZSY21 were significantly higher than those of normal control groups at different growth stages. The results afforded scientific basis for the further research on bio-controlling mechanism and DZSY21 application.