无致病力青枯菌株对烟草青枯病的控制作用

为进一步揭示无致病力菌株对烟草青枯病的控病机理,以无致病力青枯菌株为材料,针对烟草青枯病进行了温室控病及田间小区试验,并通过抗药性标记测定其抗药性突变菌株在烟株体内的定殖状况,同时分析处理后烟株体内苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)的活性变化。结果显示:无致病力菌株Tbw1-7-3在温室盆栽条件下对青枯病的相对防效达89.4%,其田间防效在发病初期10~20 d与药剂农用链霉素处理间无明显差异,且其抗药性突变株在烟株根表和体内可短暂定殖。同时菌株Tbw1-7-3能提高寄主中PAL、POD和PPO 3种酶活性及促进病程相关蛋白(PRP)的积累。无致病力菌株对烟草青枯病具有较好的控制作用,以菌株Tbw1-7-3的防效最优。田间试验也显示Tbw1-7-3菌株在发病初期具有良好的控病效果。无致病力青枯菌株的控病机理可能兼有占位效应及诱导抗病性。 

Control Effects of Avirulent Strain Tbw1-7-3 of Ralstonia Solanacearum on Tobacco Bacterial Wilt

To further reveal the control mechanism of avirulent strains of Ralstonia solanacearum against tobacco bacterial wilt, biocontrol trials were conducted in a greenhouse and field plots. The colonization of drug-resistant mutant strains in tobacco plants was determined via drug resistance marker, and the changes of activities of enzymes PAL, POD, PPO in the treated tobacco plants were analyzed. The results showed that the relative control efficacy of avirulent strain Tbw1-7-3 against tobacco bacterial wilt was up to 89.4% in greenhouse. At the early stage(10-20 days)after disease occurrence, the control efficacy of Tbw1-7-3 was comparable to that of streptomycin in fields, its drug-resistant mutant strain Tbw1-7-3k could colonize on the surface of tobacco roots and in tobacco plants for a short duration. Meanwhile,Tbw1-7-3 promoted the activities of PAL, POD, PPO and the accumulation of pathogenesis-related protein(PRP) in hosts. Avirulent strains possessed better control efficacy against tobacco bacterial wilt,especially strain Tbw1-7-3. The field experiments also indicated that Tbw1-7-3 had good control efficacy at the early stage of disease occurrence. The antagonistic mechanism of avirulent strains against Ralstonia solanacearum might be the results of both position occupying and resistance inducing.