基于根际土壤真菌和代谢物的广东梧桐山金线兰垂直分布驱动因子分析

Analysis on driving factors for the vertical distribution of Anoectochilus roxburghii in Wutong Mountain of Guangdong Province based on fungi and metabolites in rhizosphere soil

采用高通量测序和非靶向代谢组学技术,对广东梧桐山金线兰〔Anoectochilus roxburghii(Wall.)Lindl.〕核心分布区根际土壤和非分布区土壤中真菌和代谢物进行研究。结果显示:海拔875 m的金线兰核心分布区根际土壤中注释到15门401科905属真菌,海拔775 m金线兰非分布区土壤中注释到13门385科860属真菌,海拔675 m金线兰非分布区土壤中注释到15门407科890属真菌。金线兰核心分布区根际土壤与非分布区土壤真菌群落的物种丰富度和均匀度无显著差异,但群落结构与物种组成差异显著。除未知菌属外,金线兰核心分布区根际土壤中绿僵菌属(Metarhizium Sorokīn)、隔指孢属(Dactylella Grove)、被孢霉属(Mortierella Coem.)、酵母属(Saccharomyces Meyen ex E.C.Hansen)、树粉孢属(Oidiodendron Robak)、粗糙孔菌属(Trechispora P.Karst.)和Pseudophacidium P.Karst.的相对丰度高于金线兰非分布区土壤。共发生网络分析结果显示:绿僵菌属、青霉属(Penicillium Link)和弯颈霉属(Tolypocladium W.Gams)对维持金线兰核心分布区根际土壤真菌群落的结构和功能可能具有重要作用。金线兰核心分布区根际土壤和非分布区土壤中得到1886种代谢物,正离子模式鉴定到1089种代谢物,其中561种代谢物得到注释;负离子模式鉴定到935种代谢物,其中528种代谢物得到注释。金线兰核心分布区根际土壤中显著上调的差异代谢物主要有N 6,N 6,N 6-三甲基-L-赖氨酸、茯苓酸、14,15-脱氢萜烯酸、3-异丙基苹果酸、4-胆甾烯-3-酮、乙酸香茅酯和正癸酸,这些差异代谢物富集的代谢通路主要与氨基酸和脂质代谢有关,可为金线兰及其菌根真菌提供碳源和氮源。相关性分析结果显示:金线兰核心分布区根际土壤显著差异代谢物含量与主要菌属相对丰度存在密切的正相关作用。综上表明:金线兰根际土壤中非菌根真菌与菌根真菌间存在密切的相互作用,并通过碳源、氮源的营养流动影响金线兰的生长发育,进而驱动其垂直分布。

The fungi and metabolites between rhizosphere soil of core distribution area and soil of non-distribution area of Anoectochilus roxburghii(Wall.)Lindl.in Wutong Mountain of Guangdong Province were studied by the high-throughput sequencing and non-targeted metabolomics technologies.The results show that 905 genera of fungi in 401 families of 15 phyla are annotated from rhizosphere soil of core distribution area of A.roxburghii at an altitude of 875 m,860 genera of fungi in 385 families of 13 phyla are annotated from soil of non-distribution area of A.roxburghii at an altitude of 775 m,and 890 genera of fungi in 407 families of 15 phyla are annotated from soil of non-distribution area of A.roxburghii at an altitude of 675 m.There are no significant differences in species richness and evenness of fungal communities between rhizosphere soil of core distribution area and soil of non-distribution area of A.roxburghii,but there are significant differences in community structure and species composition.Except for unknown fungal genera,the relative abundances of Metarhizium Sorokīn,Dactylella Grove,Mortierella Coem.,Saccharomyces Meyen ex E.C.Hansen,Oidiodendron Robak,Trechispora P.Karst.,and Pseudophacidium P.Karst.in rhizosphere soil of core distribution area of A.roxburghii are higher than those in soil of non-distribution area of A.roxburghii.The co-occurrence network analysis result shows that Metarhizium,Penicillium Link,and Tolypocladium W.Gams may play important roles in maintaining the structure and function of the fungal community in rhizosphere soil of core distribution area of A.roxburghii.A total of 1886 metabolites are obtained from rhizosphere soil of core distribution area and soil of non-distribution area of A.roxburghii,and 1089 metabolites are identified by positive ion mode,among which 561 metabolites are annotated;935 metabolites are identified by negative ion mode,among which 528 metabolites are annotated.The significantly up-regulated differential metabolites in rhizosphere soil of core distribution area of A.roxburghii mainly include N 6,N 6,N 6-trimethyl-L-lysine,pachymic acid,14,15-dehydrocrepenynic acid,3-isopropylmalic acid,cholest-4-en-3-one,citronellyl acetate,and decanoic acid,and the metabolic pathways enriched by these differential metabolites are mainly related with amino acid and lipid metabolism,which can provide carbon and nitrogen sources for A.roxburghii and its mycorrhizal fungi.The correlation analysis result shows that there is a closely positive correlation between contents of significantly differential metabolites and relative abundances of major fungal genera in rhizosphere soil of core distribution area of A.roxburghii.In summary,there is a close interaction between non-mycorrhizal fungi and mycorrhizal fungi in rhizosphere soil of A.roxburghii,which affects the growth and development of A.roxburghii through the nutritional flow of carbon and nitrogen sources,thereby driving its vertical distribution.