植物内生细菌在棉花体内的定殖动态及对棉花黄萎病的生物防治效果
Colonization trends of endophytic bacteria in cotton and their biological control effect on cotton Verticillium wilt

为明确植物内生细菌在棉花体内的定殖规律及对棉花黄萎病防治效果的影响,采用对峙培养法筛选对大丽轮枝菌Verticillium dahliae Kleb.抑菌活性强的植物内生细菌,通过形态及生理生化特征并结合16SrDNA和gyrB基因分析鉴定菌株;利用抗生素标记法及盆栽试验研究其在棉花体内的定殖动态及对棉花黄萎病的防治效果。结果表明:共筛选到3株对大丽轮枝菌具有强抑菌活性的菌株SZ5、DP10和CCM9,其中SZ5为蜡样芽胞杆菌Bacillus cereus,定殖在棉花根部、茎部和叶部,DP10和CCM9为枯草芽胞杆菌B.subtilis,定殖在棉花根部和茎部,3株菌在棉花根部的定殖数量均在103CFU/g以上;棉花苗沾根分别接入3株内生细菌10d后再接种大丽轮枝菌孢子悬浮液,对棉花黄萎病的防治效果达79.52%~89.79%,而3株内生细菌沾根接种后立即移栽到含有大丽轮枝菌的土壤中对棉花黄萎病的防治效果为23.77%~36.03%。表明不同内生细菌菌株在棉花体内的定殖规律不同;且在棉苗中定殖一定数量后,才能对棉花黄萎病产生较高的防治效果。
In order to study the colonization of endophytic bacteria and their control effect on cotton Verticillium wilt, the endophytic bacterial strains were screened based on their efficiency of growth inhibition against Verticillium dahliae Kleb. by using agar disk diffusion, and the isolates were identified by using morphological and physiological tests combined with 16S rDNA and gyrB-based molecular analysis. The colonization dynamics and the control effect on cotton Verticillium wilt of the isolates were studied with the label of streptomycin and pot trials, respectively. The results showed that strains SZ5, DP10 and CCM9 had a notable antagonistic effect on the pathogens of V. dahliae. Strain SZ5 was identied as Bacillus cereus, and it could colonize the root, stem and leaves of the cotton plants. Strains DP10 and CCM9 were B. subtilis, and they could colonize the root and stem of the cotton plants. The quantity of colonization of the three strains in cotton roots were above 103 CFU/g. Inoculation with V. dahliaespore suspension 10 d after inoculation with endophytic bacterial strains in sterile soils showed that the control effect against cotton Verticillium wilt was 79.52%-89.79%. However, inoculation of the three endophytic bacteria strains into soils containing V. dahliaespores had a control effect against cotton Verticillium wilt of approximately 23.77%-36.03%. Different strains of endophytic bacteria had different colonization patterns in cotton, and colonizing a certain quantity of endophytic bacteria in cotton seedlings could provide greater control against cotton Verticillium wilt.