番茄内生菌的分离鉴定及菌株FQ-G3抗病促生特性

Isolation and identification of a tomato endophyte FQ-G3 and its disease-resistant and growth-promoting properties

由灰葡萄孢(Botrytis cinerea)引起的灰霉病是番茄生产中最重要的病害之一,当前使用的杀菌剂因药物残留、病原菌抗药性及食品安全等原因逐渐受到限制。因此,利用拮抗微生物的生物防治逐渐成为灰霉病防控的有效策略。【目的】从番茄植株体内筛选具有抗病促生特性内生菌株并对其生防潜力进行评估,为开发番茄灰霉病生物防治新策略提供理论依据。【方法】采用组织分离法在番茄植株不同部位分离出内生细菌、真菌,结合16SrRNA和ITS序列分析,对候选菌株进行初步鉴定;通过菌株对峙培养、果实离体接种筛选对灰葡萄孢具有拮抗活性的内生菌;进一步测定菌株分泌生长素、嗜铁素的能力及其对拟南芥和番茄幼苗生长的促生特性。【结果】从番茄植株不同部位共分离出72株内生细菌和31株内生真菌,通过平板对峙法筛选出1株对多种病原菌具有较好抑菌活性的内生细菌FQ-G3,分子鉴定为Bacillus velezensis。FQ-G3对灰葡萄孢抑菌率达80.93%,并显著抑制灰葡萄孢在番茄果实上的扩展。该菌株能够分泌生长素、蛋白酶和嗜铁素,且对拟南芥、番茄幼苗具有明显的促生效果。【结论】本研究表明分离自番茄植株的内生菌FQ-G3具有抗病促生特性,对番茄灰霉病的防控具有潜在应用价值。研究结果丰富了番茄内生菌资源,为番茄灰霉病的防病促生提供技术和理论支持。

Gray mold caused by Botrytis cinerea is one of the major diseases affecting tomato production.The currently used fungicides are gradually restricted due to residues,pathogen resistance,and food safety.Therefore,screening out antagonistic microorganisms has gradually become an effective approach for the biocontrol of gray mold.[Objective]We screened out endophytic strains capable of endowing plants with disease resistance and promoting plant growth from tomato plants and evaluated their biocontrol potential,aiming to provide a theoretical basis for developing a new approach for the biocontrol of tomato gray mold.[Methods]The endophytic bacteria and fungi were isolated from different parts of tomato plants by the tissue culture method,and the candidate strains were preliminarily identified by 16S rRNA and ITS sequence analysis.The endophytes with antagonistic activity against B.cinerea were screened by confrontation culture and fruit inoculation in vitro.Furthermore,we examined the abilities of the strain to secrete indole-3 acetic acid(IAA),protease,and siderophores and the promoting effects on the growth of Arabidopsis thaliana and tomato seedlings.[Results]A total of 72 endophytic bacterial strains and 31 endophytic fungal strains were isolated from different parts of tomato plants.An endophytic bacterium FQ-G3 with strong inhibitory activities against several pathogens was screened out and was identified as Bacillus velezensis.FQ-G3 showed the inhibition rate of 80.93% against B.cinerea in vitro and inhibited the mycelial expansion on tomato fruits in vivo.The strain could secrete IAA,protease,and siderophores,and promote the growth of A.thaliana and tomato seedlings.[Conclusion]The endophytic strain FQ-G3 isolated from tomato plants endows plants with disease resistance and promotes plant growth,and thus can serve as a candidate for the prevention and control of gray mold.The findings enrich the tomato endophyte resources and provide support for the control of gray mold and the growth promotion of tomato.