极端干旱条件对不同生长季内蒙古典型草原丛枝菌根真菌群落组成的影响

Effects of extreme drought on community composition of arbuscular mycorrhizal fungi in the typical grasslands in Inner Mongolia during different growing seasons

在全球气候变暖和降水格局改变的背景下,极端干旱事件频繁发生,影响植物群落组成,导致草原逐渐退化。丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)与大多数陆生植物形成菌根共生体,在植物适应各种逆境胁迫中发挥重要作用。为揭示极端干旱对AMF群落结构的影响,本研究以位于内蒙古自治区锡林浩特市毛登牧场的极端干旱模拟试验平台为研究对象,利用Illumina测序技术对极端干旱处理下不同生长季节土壤生态系统中AMF群落组成及其与环境因子间的相互关系进行研究。结果表明:1)在所有土壤样品中共鉴定到8属5科144个OTU,其中球囊霉属(Glomus)在所有处理中均为优势属;2)与生长季前、中期的极端干旱处理相比,生长季后期的极端干旱处理显著降低了AMF的根系侵染率和根外菌丝密度(P<0.05);3)极端干旱条件对不同生长季节的AMF物种丰富度没有显著影响,香农-威纳指数在生长季后期极端干旱中显著升高(P=0.01),同时NMDS和PERMANOVA分析显示AMF群落结构发生显著变化(P=0.022);4)土壤有机碳、C/N和pH是影响AMF群落结构差异的主要因素。

Global climate warming and precipitation variability is expected to increase both the frequency and the intensity of climate extremes,such as severe drought.As a result,the composition of plant community changed and grassland gradually degenerated.Arbuscular mycorrhizal fungi(AMF)can from symbiotic association with the majority of terrestrial plants,which play an important role in plant resistance to environmental stresses.In order to explore the effects of extreme drought on AMF community structure,the experimental platform for simulating extreme drought,Maodeng pasture in Xilin city in Inner Mongolia,was selected as the research area in this study.Based on Illumina sequencing analysis,we measured the composition of AMF community and its relationship with environmental factors in soil ecosystem during different growing seasons under extreme drought.The results showed that:1)144 OTUs belonging to 8 genera and 5 families were identified in all samples,among which Glomus was the dominant genus in all treatments.2)Compared with other extreme drought treatments,the extreme drought at the late growth season significantly reduced AMF colonization and extraradical hyphal length density(P<0.05).3)Extreme drought in different periods of the growing season did not significantly change the species richness of AMF,but Shannon-wiener index of AMF community was significantly increased under extreme drought in the late growing season(P=0.01).Meanwhile,NMDS and PERMANOVA analysis showed that the community structure of AMF changed significantly(P=0.022).4)Soil organic carbon,C/N and pH were the main factors contributing to the difference ofchanged AMF community structure.