不同根际细菌对南方根结线虫抑制效果的研究

Effect of different rhizobacteria on suppression root-knot nematode(Meloidogyne incognita)of tomato

采用稀释平板涂布方法从番茄根结土壤中初步筛选出对明胶有水解作用的菌株。通过各菌株发酵上清液对南方根结线虫二龄幼虫死亡率和虫卵孵化率抑制作用,以及拮抗菌悬浮处理番茄根系30 d后观察番茄根结数量变化,进一步筛选获得高效菌株。通过16S rDNA基因序列分析,对能显著抑制根结线虫生长的2株菌株进行了鉴定。结果表明:筛选出了10株对明胶有明显水解圈的细菌,其中菌株BTG和X5具有较强的明胶水解能力。菌株BTG和X5发酵的上清液处理二龄幼虫24 h后的死亡率比无菌上清液处理死亡率提高了72.13%和62.14%;而用菌株上清液处理14 d后的虫卵孵化率比无菌上清液处理的孵化率降低了38.62%和30.73%。菌株BTG和X5的菌悬液处理的番茄根结数比不加菌悬液对照处理根结数分别降低了80.49%和73.17%。经16S rDNA基因序列分析表明,菌株BTG和X5都属于芽孢杆菌。通过比较各株细菌对二龄幼虫(J2)死亡率,虫卵孵化率及番茄根结数量的影响,筛选出了2株可用于生物防治作物根结线虫的芽孢杆菌。

Using dilution-plate method,hydrolyzing gelatin of bacteria strains were isolated from rhizosphere soil of tomato.The mortality rate of second-stage juvenile（J2）and the eggs hatching rate of root-knot nematode were assayed for rhizosphere bacterial supernatant solutions.And tomato root-knot numbers were counted after treated with bacterial suspensions for 30 days.Two strains were identifed combined with 16S rDNA sequence analysis and biochemical and physiologic characteristics.The results indicated that ten bacterial strains had strong ability to hydrolyze gelatin,especially,BTG and X5 strains.Compared with the control treatment,after treated with BTG and X5 strain supernatant,the second-stage juvenile nematode（J2）mortality rate increased by 72.13%,62.14% within 24 h;the hatching rates of nematode eggs reduced by 38.62% and 30.73% within 14 days,respectively.Moreover,with inoculation strain BTG and strain X5,the number of tomato root-knots was reduced by 80.49% and 73.17%,respectively,compared with the non-inoculation treatment.The analysis of 16S rDNA gene sequence showed that strain BTG and strain X5 belonged to Bacillus sp.The results of second-stage juvenile mortality,egg hatching rates and tomato root-knot numbers showed that the strains BTG and X5 had potential to control root-knot nematodes.