油菜内生细菌多样性分析及菌株CanL-30生防潜力评估

为筛选防病促生的内生性细菌菌株，提高油菜的抗病性，对武汉地区甘蓝型冬油菜内生细菌进行了分离鉴定和多样性分析，同时对分离的内生细菌进行了拮抗菌株和促生菌株的筛选。结果表明：从采集到的油菜样本中共分离得到134株内生细菌，基于16S rDNA序列分析，发现这些菌株属于18个细菌属中的33个种，其中芽孢杆菌属、假单胞菌属和寡养单胞菌属占优势，分别占分离物总数的46.27%、15.67%和11.94%。油菜根、茎和叶内生细菌分离物的香农多样性指数分别为2.847、2.808和2.356，辛普森指数分别为0.956、0.939和0.907。经过平板筛选、离体叶片筛选以及活体油菜接种筛选，发现枯草芽孢杆菌（Bacillus subtilis）菌株CanL-30对灰葡萄孢（Botrytis cinerea）、立枯丝核菌（Rhizoctonia solani）和油菜黑胫病菌（Leptosphaeeria biglobosa）有拮抗作用，还具有稳定的抑制核盘菌的效果。进一步试验表明，菌株CanL-30主要通过产生抗真菌物质抑制核盘菌生长。研究还发现CanL-30能促进拟南芥和油菜生长。上述结果说明冬油菜存在丰富的内生细菌资源，从中可以筛选得到防病促生的细菌菌株。

Diversity of endophytic bacteria in Brassica napus and biocontrol potential of Bacillus subtilis CanL-30

 To investigate the biocontrol efficacy of rapeseed (Brassica napus) endophytic bacteria, bacteria were isolated from rapeseed seedlings in Wuhan, and their diversity was studied. Results showed that the obtained 134 strains included 33 genera and 18 species based on their 16S rDNA sequences. Among them, 3 genera Bacillus, Pseudomonas and Stenotrophomonas accounted for 46.27%, 15.67% and 11.94% respectively, of the total. The endophytic bacteria in roots, stems and leaves had Shannon diversity indices of 2.847, 2.808 and 2.356 respectively, and had Simpson’s indices of 0.956, 0.939 and 0.907 respectively. Bacillus subtilis strain CanL-30 was selected based on dual culturing screening using in vitro and in vivo screenings on leaves. It showed that CanL-30 inhibited Botrytis cinerea, Rhizoctonia solani and Leptosphaeeria biglobosa on plates. It’s suppression had high antifungal efficacy on Sclerotinia sclerotiorum on rapeseed leaves. Furthermore CanL-30 promoted plant growth of both rapeseed and Arabidopsis thaliana inside the plates possibly through volatiles. This study suggested that rapeseed endophytic bacteria were highly diverse, and could be the important biological resource of bacteria on both biocontrol and plant-growth promoting.