盐碱胁迫对染内生菌和不染菌苇状羊茅根系丛枝菌根真菌群落多样性和组成的影响

Effects of soil saline-alkali stress on arbuscular mycorrhizal fungal community diversity and composition of roots of endophyte-infected and endophyte-free tall fescue

香柱菌属Epichlo?内生真菌存在于宿主植物地上部组织,不仅能提高宿主植物对生物与非生物逆境的抗性,而且能对周围环境中的微生物产生影响。该研究以染内生菌(endophyte-infected,EI)和不染菌(endophyte-free,EF)苇状羊茅Festucaarundinacea为实验材料,探究内生真菌和不同水平盐碱胁迫处理对宿主根系丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落多样性和组成的影响。结果表明,内生真菌和盐碱胁迫处理对苇状羊茅根系AMF多样性影响存在交互作用。EF苇状羊茅根系AMF多样性随盐碱胁迫处理水平的增加而降低,内生真菌的存在缓解了这一效应,在200和400 mmol/L盐碱胁迫处理下,内生真菌感染增加了苇状羊茅根系AMF多样性;此外,内生真菌感染改变了苇状羊茅根系AMF群落组成,降低了优势属Funneliformis相对多度,增加了Claroideoglomus、Glomus和unclassified AMF相对多度。结构方程模型结果表明,内生真菌通过间接增加土壤总磷浓度对苇状羊茅根系AMF多样性产生影响。本研究为筛选盐碱污染区生态修复的植物-微生物共生体提供基础。

Epichlo?endophytes are widespread symbionts of plants that asymptomatically inhabit aerial host tissues,and not only confer tolerance to biotic and abiotic stresses,but also affect soil microbes.Endophyte-infected(EI)and endophyte-free(EF)Festuca arundinacea are used as experimental materials to investigate the effects of endophyte Epichlo?and soil saline-alkali stress on the arbuscular mycorrhizal fungal(AMF)diversity and community composition in roots of tall fescue.A pot experiment under endophyte infection(EI and EF)and saline-alkali stress treatments(0,200,400 and 600 mmol/L)was conducted.There are five replicates per treatment.AMF diversity in roots of tall fescue is determined by high throughput sequencing.The diversity of AMF in EF tall fescue roots decreased with the increase of saline-alkali stress treatment level,and the presence of the endophytes alleviated this effect.Under the 200 and 400 mmol/L saline-alkali stress treatments,the endophytes increased the diversity of AMF in tall fescue roots;in addition,the endophytes caused a shift in AMF community composition,reducing the relative abundance of Funneliformis and increasing the relative abundance of Claroideoglomus,Glomus and some unclassified AMF.The results of structural equation model(SEM)showed that the endophytes increased the AMF diversity of tall fescue roots by increasing the concentration of soil total phosphorus under saline-alkali stresses.This study provides reference for selecting the plant-microbial symbionts during ecological restoration in areas with saline-alkali pollution.