黄瓜枯萎病拮抗菌的分离鉴定及其生物防效

从黄瓜根际土壤和根、茎中分离出对黄瓜枯萎病病原菌——尖孢镰刀菌黄瓜专化型具有较强拮抗作用的细菌菌株7株,这些细菌在平板上对尖孢镰刀菌的抑菌效果最高可达46%。经济福平抗生素诱导抗性后,这7株菌株共得到具有抗性的菌株4株:GJ-9、NH-1、P_7、XX_2J_7。检测有利福平标记的菌株在黄瓜苗根系和植株内的定殖能力,结果显示菌株在黄瓜苗具有良好的定殖能力,并且能通过根部运输进入茎中,从而显著提高黄瓜苗的PAL、POD和PPO防御酶活性。盆栽试验结果表明:将筛选到的7株拮抗菌的发酵液对黄瓜苗进行处理,其中拮抗菌NH-1的发酵液对黄瓜枯萎病具有显著的防治效果,其处理后的黄瓜苗病情指数为26.00,防治效果达到66.03%。根据其生长形态特征及对其进行gyrb基因序列分析,鉴定其为贝莱斯芽胞杆菌(Bacillus velezensis)。

Isolation and identification of antagonistic bacteria and biological control efficiency on cucumber Fusarium wilt

Seven bacterial strains with strong antagonistic effect on the pathogen of cucumber Fusarium oxysporum were isolated from the rhizosphere soil,root and stem of cucumber,and the inhibition rate of these bacteria on the plate was up to 46%. Four strains including GJ-9,NH-1,P7 and XX2J7 with resistance to rifampicin were obtained. The results showed that these strains had good colonization ability in the cucumber seedling and could be transported into the stem through the root,which could significantly improve the activity of defense-related enzyme such as PAL,POD and PPO in the cucumber seedlings. The results showed that the fermentation broth of the antagonistic bacteria NH-1 had significant effect on the control of the cucumber Fusarium wilt,the disease index of the treated cucumber seedlings was 26.00,and its control effect reached 66.03%. According to the growth morphological characteristics and its gyrb gene sequence analysis,this bacteria was identified as Bacillus velezensis.