拮抗线虫的花生根瘤内生细菌筛选及鉴定

Identification of endophytic bacteria strains in peanut nodules of Meloidogyne hapla

用拮抗内生细菌控制根结线虫具有重要意义。于全国范围内选择不同生境的地块采集土样,室内诱集花生根瘤,获得了丰富的根瘤内生细菌种群。利用半根瘤法从花生根瘤中分离内生细菌,以北方根结线虫为靶标,筛选其中对根结线虫二龄幼虫具有高毒力的内生细菌菌株。在诱集获得的637个根瘤样本中,有19个处理二龄幼虫致死率达80%以上的高效根瘤样本,其中2个根瘤样本处理24h时致死率可达94%。通过对19个根瘤样本的内生菌进行分离纯化,获得123株内生菌,通过对其发酵液杀线虫活性进行研究获得活性较高的9个菌株,其中Sneb1706处理二龄幼虫24h致死率达到91.4%,Sneb1872对卵的孵化抑制率可达到59.4%,Sneb1773对植物表现出明显的促生作用。经16S RNA序列分析和生理生化鉴定,这9个高杀线虫活性的根瘤内生菌菌株属于假单胞菌属(Pseudomonas)、寡氧单胞属(Stenotrophomonas)和根瘤菌属(Rhizobium)。

It is of great importance to make use of endophytes in antagonism controlling on Meloidogyne. In order to obtain a wide variety of endophytic bacteria strains,soil samples were collected from different ecological environment to trap peanut nodules. Endophytes were separated from peanut nodule by using half- of- a- nodule method,and endophytic bacteria strains with higher toxicity to 2- year- old larva（ J2） of root knot nematodes were selected. Among 637 nodule samples,19 efficient nodule had higher lethal rate over 80%. The highest lethal rate was over 94% after 24 h. 123 endophytic bacteria strains were separated and purified from above 19 nodule samples,and their fermentation nematicidal activities were compared. Results showed that,9 bacterial strains had higher activity,especially Sneb 1706 could cause 91. 4% mortality of J2 after 24 h,and Sneb1872 had an incubation inhibition ratio of 59. 4%. Meanwhile,Sneb1773 showed obvious growth promoting effect on plants. 16 S RNA sequence analysis,and their physiological and biochemical identification indicated that these 9 strains of nodule endophytes belonged to Pseudomonas,Rhizobium and Stenotrophomonas.