南疆四种盐生植物根际土壤真菌群落结构特征

Abstract

盐生植物特殊的生境孕育了独特的根际微生物群落。为了解南疆干旱区不同盐生植物根际土壤真菌群落结构特征，探讨影响真菌群落结构的土壤环境因子，选取南疆伽师县同一盐碱地盐爪爪（Kalidium foliatum）、黑果枸杞（Lycium ruthenicum）、花花柴（Karelinia caspia）和旱生芦苇（Phragmites australis）四种优势盐生植物，采用Illumina NovaSeq高通量测序技术分析根际土壤真菌群落结构和多样性，并探究其与土壤理化因子的相关性。结果表明，四种盐生植物根际土壤理化特征不尽相同，土壤pH均超过8.0，电导率（EC）由高到低为旱生芦苇 > 盐爪爪 > 花花柴 > 黑果枸杞，黑果枸杞根际土壤的有机质（SOM）、全氮（TN）、全磷（TP）、全钾（TK）、速效氮（AN）和速效磷（AP）含量均最高，旱生芦苇根际土壤的SOM、TN、TP、TK和AN值均最低，但土壤水分含量（SWC）和EC值最高。四种盐生植物共有的操作分类单元（OTUs）数量为153个，各自特有的OTUs数量不尽相同。根际土壤真菌群落丰富度（ACE、Chao 1指数）依次为盐爪爪 > 旱生芦苇 > 黑果枸杞 > 花花柴，Shannons指灵第和Simpson指数大小依次为盐爪爪 > 黑果枸杞 > 旱生芦苇 > 花花柴。从四种盐生植物根际共检测到真菌8门、21纲、44目、89科、124属，子囊菌门（Ascomycota）在四种盐生植物根际土壤中占绝对优势地位。镰孢菌属（Fusarium）、支顶孢属（Acremonium）、曲霉属（Aspergillus）和青霉菌属（Penicillium）是四种盐生植物根际土壤共有优势属，非优势属数量多但相对丰度因植物种类而异。典范对应分析（CCA）显示，土壤速效钾、AP、pH和EC是影响根际土壤真菌群落结构变化的主要驱动因子。研究表明南疆四种盐生植物根际土壤真菌群落具有相似性，但优势菌属丰度差异明显，具有植物种类特异性。;Halophytes harbour unique rhizosphere microbial communities as a result of their unique habitat. The rhizosphere soil fungal diversity and community structures of four halophytes, including Kalidium foliatum, Lycium ruthenicum, Karelinia caspia and Phragmites australis, typically distributed in the arid land of Southern Xinjiang, were studied using the Illumina high-throughput sequencing technology. The study aims to reveal the alpha diversity, species composition, abundance and the differences of rhizosphere soil fungi among the four halophytes, explore their correlation with environmental factors to provide the basis for further investigation of the relationship between rhizosphere soil microbes and salt tolerance of halophytes. The results showed that the physicochemical characteristics of the rhizosphere soil of the four halophytes were different. The soil pH was all over 8.0, and the electronic conductivity (EC) value from high to low was Phragmites australis, Kalidium foliatum, Karelinia caspia, Lycium ruthenicum. The soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN) and available phosphorus (AP) contents in the rhizosphere soil of Lycium ruthenicum were the highest, while the SOM, TN, TP, TK and AN values were the lowest in Phragmites australis, but the SWC and EC value were the highest. The numbers of operational taxonomic units (OTUs) unique to Kalidium foliatum, Lycium ruthenicum, Karelinia caspia, and Phragmites australis were 51, 19, 11, and 53 respectively, as well as their common OTUs number was 153. The fungi community richness (abundance-based coverage estimator, ACE and Chao 1 index) from high to low was Kalidium foliatum, Phragmites australis, Lycium ruthenicum, and Karelinia caspia. The fungal community was different in composition and abundance in the rhizosphere of the four halophytes. A total of 8 phyla, 21 classes, 44 orders, 89 families, and 124 genera fungi were detected in their rhizosphere soil samples. The relative abundance and distribution of fungi varied at phylum level, and the dominant groups were Ascomycota, Basidiomycota, and Chytridiomycota. There were 11, 9, 8, and 6 genera with relative abundance greater than 1% in the rhizosphere soil of Kalidium foliatum, Lycium ruthenicum, Karelinia caspia, and Phragmites australis, respectively, with 4 common dominant genera including Fusarium, Acremoniuma, Aspergillus and Penicillium. The number of non-dominant fungi was large but the relative abundance varied with plant species. Then each plant had its particular or mutual fungal genera with different abundance, some of which were affected greatly by soil physicochemical properties. According to canonical correlation analysis (CCA), we found that the major influence factors that caused the change of soil fungal community structures of the four halophytes were oil available potassium, available phosphorus, pH and electrical conductivity. This study revealed that the rhizosphere soil fungi communities of the four halophytes were similar, but the abundance of dominant bacteria was significantly different, with plant species specificity. The rhizosphere fungi community was correlated with the soil environmental factors.