非洲哈茨木霉LMNS-M9的鉴定、生物学特性及其对藜麦的促生作用

Trichoderma afroharzianum LMNS-M9: identification, biological characteristics, and growth-promoting effect on quinoa

摘要:

【背景】藜麦作为风靡全球的功能性食品，其种子内生非洲哈茨木霉的研究尚未见报道。【目的】从藜麦种子中筛选出有抑菌活性的内生真菌，分析其抑菌和促生作用。【方法】通过形态学及ITS、tef1和rpb2基因序列等方法对筛选出的内生真菌进行鉴定；采用平板对峙和平板倒扣等方法测定内生真菌的抑菌活性；利用盆栽试验测定内生菌株对藜麦生长的影响。【结果】综合形态学特征和系统发育分析结果，确定菌株LMNS-M9为非洲哈茨木霉(Trichoderma afroharzianum)。30 ℃、pH 5.0和镁离子适宜菌株LMNS-M9菌丝生长和产孢；葡萄糖、乳糖、蛋白胨、磷酸二氢钾适宜菌株LMNS-M9菌丝生长；葡萄糖、硝酸铵、磷酸氢二钾适宜菌株LMNS-M9产孢。菌株LMNS-M9对Botrytis cinerea、Ascochyta caulina、Fusarium citri、Alternaria alternata和Trichothecium roseum的抑制率分别为12.53%、51.96%、52.38%、59.25%和62.04%，挥发物的抑制率分别为35.86%、61.54%、33.33%、41.95%和59.09%。菌株LMNS-M9可接触或缠绕病原菌(B. cinerea、A. caulina、F. citri、A. alternata)的菌丝，致使其断裂、消解。盆栽试验发现，菌株LMNS-M9可促进藜麦种子提前2 d萌发，并使幼苗根长、地下部鲜重和地下部干重分别增加71.88%、104.66%和68.89%。【结论】从藜麦种子中分离的内生真菌鉴定为非洲哈茨木霉(T. afroharzianum)，能抑制5种病原菌，同时可促进藜麦出苗和根系生长，具有较好的生防潜力。

Abstract:

[Background] Quinoa is an example of functional food that is popular all over the world, while little has been reported about the endophyte Trichoderma afroharzianum of quinoa seeds. [Objective] To determine the antimicrobial activity and growth-promoting effect of endophytic fungi isolated from quinoa seeds. [Methods] The isolated endophytic fungi were identified based on morphology and the ITS, tef1, and rpb2 gene sequences characteristics. The antimicrobial effects of endophytic fungi were determined by plate confrontation method and plate culture method. The growth-promoting effect of the strain on quinoa was determined by pot experiment. [Results] The strain LMNS-M9 was identified as T. afroharzianum. The mycelial growth and sporulation of strain LMNS-M9 were promoted at 30 ℃, pH 5.0, and the presence of magnesium ion. Glucose, lactose, peptone, and potassium dihydrogen phosphate were suitable for mycelial growth of strain LMNS-M9, and glucose, ammonium nitrate, and dipotassium hydrogen phosphate were suitable for sporulation. LMNS-M9 showed inhibitory activity against Botrytis cinerea, Ascochyta caulina, Fusarium citri,Alternaria alternata, and Trichothecium roseum, with the inhibition rates of 12.53%, 51.96%, 52.38%, 59.25%, and 62.04%, respectively. The volatiles showed the inhibition rates of 35.86%, 61.54%, 33.33%, 41.95%, and 59.09%, respectively. LMNS-M9 could contact or entangle the mycelia of pathogens (B. cinerea, A. caulina, F. citri, and A. alternata) to rupture or lyse the mycelia. The pot experiment showed that LMNS-M9 advanced the germination of quinoa seeds by 2 days. Furthermore, LMNS-M9 increased the root length, underground fresh weight, and underground dry weight of quinoa seedlings by 71.88%, 104.66%, and 68.89%, respectively. [Conclusion] The endophytic fungus isolated from quinoa seeds was identified as T. afroharzianum. It inhibited the growth of five pathogens and promoted the root growth of quinoa, demonstrating good biocontrol potential.