具防病并提高植物耐旱功能的小链霉菌HS57的筛选

Screening of Streptomyces parvus HS57 with the biocontrol function and ability to enhance the plant’s tolerance to water shortage stress

本研究旨在寻找防治黄瓜枯萎病并提高植物抗逆能力的多功能菌株。从连作田健康黄瓜根际土中分离筛选到1株放线菌HS57。平板对峙法测定菌株HS57对尖孢镰刀菌、茄病镰刀菌和立枯丝核菌的抑制作用,平皿对扣共培养法测定其挥发性物质对尖孢镰刀菌的抑制作用,温室盆栽法测定其对黄瓜枯萎病的防病效果及对小麦耐旱能力的影响,结合菌株形态特征和16S rRNA基因序列分析对其进行鉴定。结果表明,菌株HS57可抑制3种病原菌生长,其中对尖孢镰刀菌的抑制率为52.4%;其挥发性物质对尖孢镰刀菌的抑制率为32.1%。浓度为10^7个/mL的HS57孢子悬浮液浸种对黄瓜枯萎病的防效最好,为51.0%;小麦种子经浓度为10^7、10^8个/mL的HS57孢子悬浮液浸种,麦苗经连续7 d缺水处理后再浇水,比对照恢复得更好。初步鉴定HS57菌株为小链霉菌Streptomyces parvus,是一株非常有潜力的多功能菌株。

The purpose of this study is to find a multifunctional strain to control cucumber wilt disease and enhance the plant’s tolerance to unfavorable conditions. An actinomycete strain HS57 with strong antagonistic effect on Fusarium oxysporum f.sp. cucumerinum(Foc) was isolated from the rhizosphere soil of the healthy cucumber plants. The inhibitive activity of strain HS57 on mycelial growth of F.oxysporum, F.solani and Rhizoctonia solani was determined by using pair-culturing method. In addition, the effect of its volatiles on Foc growth was determined by using an up-down co-culturing method with the plates separately inoculated with HS57 and Foc. The efficacy of strain HS57 in suppressing cucumber wilt disease and its ability to improve the wheat tolerance to water shortage stress were tested in the greenhouse by seed soaking with different concentrations of HS57 spores. Strain HS57 was identified based on the morphological characteristics and 16 S rRNA gene sequence analysis. The results showed that strain HS57 inhibited the mycelial growth of F.oxysporum, F.solani and R.solani. Among the three fungi, F.oxysporum was suppressed with an inhibitive rate of 52.4%. Moreover, the volatiles produced by strain HS57 also had a good ability to inhibit F.oxysporum growth with an inhibitory rate of 32.1%. In the greenhouse assay, strain HS57 showed good control efficacy(51.0%) against cucumber fusarium wilt at the concentration of 10^7 spores/mL. Seed treatments with 10^7 and 10^8spores/mL of strain HS57 also enhanced the wheat tolerance to water shortage stress, demonstrated by better recovery of the seedlings than the control after 7 d-non-irrigation and re-irrigation. Strain HS57 was identified as Streptomyces parvus based on its morphological characteristics and its 16 S rRNA gene sequence analysis. As a multifunctional strain, HS57 showed a great potential for practical application.