典型生境巨菌草根内生固氮菌的群落多样性

【目的】探究不同生境巨菌草内生固氮菌群落组成多样性及其分异规律。【方法】采用高通量测序固氮酶nif H标靶基因方法,研究了我国6个典型地区的巨菌草内生固氮菌群,包括福建闽侯县、新疆墨玉县、内蒙古阿拉善左旗、青海贵德县、甘肃安定区、海南那大镇,结合地理气候因子统计,分析了固氮菌多样性的环境驱动机制。【结果】共获得64122条nif H基因的有效序列,640个OTUs,归属于6个门、10个纲、17个目、24个科、33个属和39个种。不同地区巨菌草中优势内生固氮菌群的种类和丰度存在较大的差异。在门水平上,福州闽侯县、甘肃安定区、新疆墨玉县、内蒙古阿拉善左旗和青海贵德县5个地区的优势菌门均为变形菌门,海南那大镇的优势菌门为变形菌门和蓝藻菌门;属水平上,不同地区巨菌草最优势内生固氮菌类群分别为:福州闽侯县(变形菌门中未定属,80.56%);新疆墨玉县(变形菌门中未定属,33.14%);内蒙古阿拉善左旗(变形菌门中未定属,76.23%);甘肃安定区(α-变形菌纲中的未定属,53.78%);海南那大镇(变形菌门中未定属,38.37%);青海贵德县(变形菌门中未定属,46.12%)。Alpha多样性和Beta多样性分析表明,不同地区巨菌草内生固氮菌群落的多样性存在较大的差异,海南那大镇样本中巨菌草各类内生固氮菌群的多样性及丰富度最高,福建闽侯县样本中巨菌草各类内生固氮菌群的多样性及丰富度最低。典范对应分析(CCA)结果表明,年均降雨量和年均气温是影响巨菌草内生固氮菌群变化的主要因素,其次是土壤有机质、土壤全氮和土壤p H。【结论】不同地区巨菌草内生固氮菌群落的组成及丰度存在着较大的差异,海南那大镇巨菌草内生固氮菌群的种类及相对丰度较高,本研究可为巨菌草内生固氮菌群的资源开发及其固氮微生物肥料的菌种选育和生产应用提供理论支持。

Diversity of endophytic nitrogen-fixing bacteria community in the roots of Pennisetum sp. of typical habitats

Objective] To explore the diversity and differentiation of endophytic nitrogen-fixing bacteria community in Pennisetum sp. in different habitats. Methods] High-throughput sequencing of nitrogen-fixing enzyme nifH target gene method was used to study the endophytic nitrogen-fixing bacteria in Pennisetum sp. in 6 typical areas of China, including Fujian Minhou County, Xinjiang Moyu County, Inner Mongolia Alashan Zuoqi, Qinghai Guide County, Gansu Anding District, and Hainan Nada Town. The environmental driving mechanism of nitrogen-fixing bacteria diversity was analyzed by combining geographical and climatic factor statistics. Results] A total of 64122 valid sequences of nifH genes were obtained, 640 OTUs belonging to 6 phyla, 10 classes, 17 orders, 24 families, 33 genera and 39 species. The species and abundance of predominant endophytic nitrogen-fixing bacteria in Pennisetum sp. from different regions were quite different. At the phylum level, Proteobacteria were the dominant bacteria in the five areas of Fuzhou Minhou County, Gansu Anding District, Xinjiang Moyu County, Inner Mongolia Alashan Zuoqi and Qinghai Guide County, whereas Proteobacteria and Cyanobacteria were the dominant phylum in Hainan Nada town. At the genus level, the most dominant endogphytic nitrogen-fixing bacteria groups in Pennisetum sp. in different regions as below:Minhou County of Fuzhou province (undetermined genus of Proteobacteria, 80.56%), Moyu County of Xinjiang province (undetermined genus of Proteobacteria, 33.14%), Alashan Zuoqi of Inner Mongolia (undetermined genus of Proteobacteria, 76.23%), Anding District of Gansu Province (undetermined genus of Alphaproteobacteria, 53.78%), Nada Town of Hainan (undetermined genus of Proteobacteria, 38.79%), Guide County of Qinghai (undetermined genus of Proteobacteria, 46.12%). The analysis of alpha-diversity and beta-diversity showed that the diversity of endophytic nitrogen-fixing bacteria communities in Pennisetum sp. in different regions was different. The diversity and richness of endophytic nitrogen-fixing bacteria in Pennisetum sp. in Nada Town of Hainan Province were the highest, while those in Minhou County of Fujian province were the lowest. The canonical correspondence analysis (CCA) showed that annual average rainfall and annual average temperature were the main factors affecting the change of endophytic nitrogen-fixing bacteria in Pennisetum sp., followed by soil organic matter, soil total nitrogen and soil pH. Conclusion] The composition and abundance of endophytic nitrogen-fixing bacteria community in Pennisetum sp. in different areas were quite different. The species and relative abundance of endophytic nitrogen-fixing bacteria in Pennisetum sp. in Nada town of Hainan province were relatively high. This research can provide theoretical supports for the development of endophytic nitrogen-fixing bacteria in Pennisetum sp. and the breeding and production of nitrogen-fixing microbial fertilizers.