The Community Structure and Functional Diversity of Soil Microbes in the Rhizosphere of Different Plants in the Anxi Extreme Arid Desert in China
本研究分别于2015年、2016年和2017年7月在甘肃安西极旱荒漠国家级自然保护区采集膜果麻黄(Ephedra przewalskii)、红砂(Reaumuria songarica)、合头草(Sympegma regelii)、泡泡刺(Nitraria sphaerocarpa)和珍珠猪毛菜(Salsola passerina)5种典型荒漠植物根际土壤样品,利用磷脂脂肪酸(PLFA)法结合Sherlock微生物鉴定系统和BIOLOG分析法研究了不同植物根际土壤微生物群落结构、功能多样性及与土壤因子的相关关系,以期为干旱风沙区植被恢复和生态环境保护提供依据。主要试验结果如下:(1)不同荒漠植物根际土壤微生物群落结构差异显著。总PLFA、革兰氏阴性菌、革兰氏阳性菌和放线菌表现为珍珠猪毛菜≈膜果麻黄>泡泡刺>红砂>合头草,非AMF真菌在合头草根际显著低于其它植物,AM真菌在膜果麻黄和红砂根际显著最低。细菌/总PLFA在合头草根际最高、膜果麻黄根际最低,真菌/总PLFA趋势相反,革兰氏阳性菌/革兰氏阴性菌在合头草根际显著高于其它植物。革兰氏阳性菌17:1 isoω9c在膜果麻黄根际显著最高;革兰氏阳性菌12:0 anteiso、13:0 anteiso,革兰氏阴性菌14:1ω8c在红砂根际有最高值;革兰氏阳性菌15:0 iso,革兰氏阴性菌16:1ω9c,放线菌18:1ω7c10-methyl在珍珠猪毛菜根际显著高于其它植物。(2)平均颜色变化率(AWCD)在膜果麻黄中显著高于其它植物。5种植物根际土壤微生物对碳水化合物、多聚物类利用能力最高,羧酸、氨基酸类次之,酚酸和胺类显著最低。膜果麻黄和合头草对31种碳源均有较高的利用能力,红砂对D-半乳糖醛酸、吐温80、α-丁酮酸、L-精氨酸、L-丝氨酸和腐胺的利用能力较弱,泡泡刺对β-甲基-D-葡萄糖苷、D-木糖/戊醛糖、D-半乳糖酸γ-内酯、α-丁酮酸和D-苹果酸利用较少,珍珠猪毛菜几乎不利用D-半乳糖酸γ-内酯。(3)土壤全氮与非AMF真核生物、AM真菌、厌氧菌显著正相关,与革兰氏阳性菌显著负相关;酸性磷酸酶与革兰氏阳性菌显著负相关;易提取球囊霉素与非AMF真核生物极显著正相关。(4)土壤pH、全磷与与碳水化合物、多聚物类、羧酸类和胺类的利用率显著正相关;全氮、氨氮与羧酸类、酚酸类和氨基酸类利用率显著负相关;酸性磷酸酶与酚酸类、胺类显著负相关;总球囊霉素与羧酸类显著负相关。(5)革兰氏阳性菌与酚酸类、氨基酸类和胺类碳源利用显著正相关,其它碳源利用情况与土壤微生物群落类群无显著相关关系。
In this study,the rhizosphere soils of Ephedra przewalskii,Reaumuria songarica,Sympegma regelii,Nitraria sphaerocarpa and Salsola passerina in Anxi Extreme-arid Desert National Nature Reserve in Gansu Province,China were collected in July 2015,2016 and2017.In order to provide the basis for vegetation restoration and ecosystem conservation in arid areas,we analyzed the community structure and functional diversity of soil microbes in the rhizosphere of the studied five plants and correlation with edaphic variables by using phospholipid fatty acid(PLFA)combined with Sherlock microbial identification system and BIOLOG analysis.The main results are as follows:(1)The community structure of soil microbes in the rhizosphere of different desert plants was significantly different.Total PLFA,gram-negative bacteria,gram-positive bacteria and actinomycetes were shown as E.przewalskii≈S.passerina>N.sphaerocarpa>R.songarica>S.regelii;non-AMF fungi in the rhizosphere of S.regelii was significantly lower than that of other plants;AM fungi was the lowest in the rhizosphere of E.przewalskii and R.songarica.Bacteria/total PLFA was the highest in the rhizosphere of S.regelii and the lowest that of E.przewalskii,and fungi/total PLFA showed a reverse trend;gram-positive/gram-negative bacteria in the rhizosphere of S.regelii was significantly higher than that of other plants.Characterization of gram-positive bacteria 17:1 iso ω9c was the highest in the rhizosphere of E.przewalskii;characterizations of gram-positive bacteria 12:0anteiso and 13:0 anteiso,and 14:1 ω8c indicating gram-negative bacteria had the highest value in the rhizosphere of R.songarica;15:0 iso,16:1 ω9c and 18:1 ω7c 10-methyl characterizing gram-positive bacteria,gram-negative bacteria and actinomycetes,respectively,were significantly higher in the rhizosphere of S.passerina than that of other plants.(2)The average well color development(AWCD)in the rhizosphere of E.przewalskii was significantly higher than that of other plants.The utilization of carbohydrates and polymers were the most,followed by carboxylic acids and amino acids,and amines least in rhizosphere of different desert plants.31 kinds of carbon sources can be well utilized by soilmicrobes in the rhizosphere of E.przewalskii and S.regelii;the utilization of D-galacturonic acid,Tween 80,α-butanone acid,L-arginine,L-serine and putrescine were less than that of other carbon sources in the rhizosphere of R.songarica;the utilization ofβ-methyl-D-glucoside,D-xylose/aldopentose,D-galactoacid γ-lactone,α-butanone acid and D-malic acid were little in the rhizosphere of N.sphaerocarpa,and D-galactoacid γ-lactone was hardly used in the rhizosphere of S.passerina.(3)Total nitrogen was positively correlated with non-AMF eukaryotes,AM fungi and anaerobe,and negatively correlated with gram-positive bacteria;acid phosphatase was negatively correlated with gram-positive bacteria,and easily extracted glomalin was positively correlated with non-AMF eukaryotes.(4)Soil pH and total phosphorus were positively correlated with the utilization of carbohydrates,polymers,carboxylic acids and amines;total nitrogen and ammonia nitrogen were negatively correlated with the utilization of carboxylic acids,phenolic acids and amino acids;acid phosphatase was significantly negatively correlated with the utilization of phenolic acids and amines;total glomalin was negatively correlated with the utilization of carboxylic acids.(5)Gram-positive bacteria were positively correlated with the utilization of phenolic acids,amino acids and amines;however,there was no significant correlation between other soil microbial groups and the utilization of other carbon sources.