腾格里沙漠东南缘沙蒿根际与非根际土壤微生物群落结构及其多样性变化特征

Structural characteristics and diversity dynamics of soil microbial communities in the rhizosphere and non-rhizosphere of Artemisia desertorum at the southeastern edge of the Tengger Desert

摘要:

沙蒿(Artemisia desertorum)是腾格里沙漠的优势沙生植物，具有显著的抗旱、耐盐碱和固沙能力。目的 通过探究腾格里沙漠东南缘宁夏沙坡头自然保护区内沙蒿根际与非根际土壤微生物群落多样性，并分析优势菌属与植物之间的潜在关系，为荒漠生态治理提供理论依据。方法 以固沙42年的沙蒿根际和非根际土壤为研究对象，并以20 cm深且无植物覆盖的流沙为对照，运用高通量测序技术分析其真菌和细菌群落特征，并对其土壤理化性质进行分析。结果 根际和非根际土壤的全氮(total nitrogen, TN)、碱解氮(alkali-hydrolyzable nitrogen, AN)、速效钾(available potassium, AK)均显著高于流沙区域(P<0.05)。根际土壤的速效磷(available phosphorus, AP)、速效钾(AK)、有机质(organic matter, OM)和电导率(electrical conductivity, EC)显著高于非根际土壤(P<0.05)；尽管根际土壤的全氮(TN)、全磷(total phosphorus, TP)、碱解氮(AN)和pH (potential of hydrogen)值略高于非根际土壤，但差异不显著。根际土壤的细菌多样性和丰度低于非根际土壤，而真菌多样性和丰度较高。根际与非根际土壤的特有微生物操作分类单元(operational taxonomic unit, OTU)均多于流沙，其中根际土壤的真菌OTUs多于非根际土壤，细菌OTUs则较少。共有优势真菌门包括子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、Unclassified fungal phyla和罗兹菌门(Rozellomycota)，主要优势真菌属为假丝酵母菌属(Candida)、异茎点霉菌属(Paraphoma)、链格孢霉菌属(Alternaria)、未分类菌属Unclassified fungal genera和青霉菌属(Penicillium)；优势细菌门包括放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、拟杆菌门(Bacteroidota)、绿屈挠菌门(Chloroflexi)和酸杆菌门(Acidobacteria)，主要优势细菌属为节杆菌属(Arthrobacter)、类诺卡氏菌属(Nocardioides)、链霉菌属(Streptomyces)、农霉菌属(Agromyces)和鞘氨醇单胞菌属(Sphingomonas)。线性判别分析效应大小(linear discriminant analysis effect size, LEfSe)分析显示，根际土壤中212个细菌类群和25个真菌类群显著区别于非根际土壤，关键类群分别为子囊菌门和变形菌门。冗余分析(redundancy analysis, RDA)表明，有机质(OM)是土壤微生物群落结构的主要影响因子，与担子菌门、酸杆菌门、绿屈挠菌门和Unclassified fungal phyla呈正相关，与子囊菌门、罗兹菌门、放线菌门、变形菌门和拟杆菌门呈负相关。结论 在腾格里沙漠东南边缘，种植沙蒿显著提升了根际土壤养分水平及真菌群落的多样性与丰度，从而增强了土壤生态系统的稳定性。本研究为区域生态修复提供了理论支持，并为沙蒿生态恢复效果的优化与可持续管理提供了科学依据。

Abstract:

Artemisia desertorum, a dominant xerophyte in the Tengger Desert, possesses exceptional drought resistance, salt tolerance, and sand-fixing capabilities.Objective To investigate the diversity of soil microbial communities in the rhizosphere and non-rhizosphere of A. desertorum in the Shapotou Nature Reserve located at the southeastern edge of the Tengger Desert, Ningxia, and the potential interactions between the dominant microbial genera and plants, thus laying a theoretical foundation for ecological restoration in deserts.Methods Soil samples were collected from the rhizosphere and non-rhizosphere of A. desertorum, in the plantation cultivated for 42 years of sand fixation, and the sand was collected as the control. Physicochemical properties of each soil sample were measured, and fungal and bacterial communities were analyzed via high-throughput sequencing.Results Total nitrogen (TN), available nitrogen (AN), and available potassium (AK) in the rhizosphere and non-rhizosphere soil samples were significantly higher than in shifting sands those in the control (P<0.05). Rhizosphere soil samples also had significantly higher levels of available rhizosphere soils also had significantly higher levels of available phosphorus (AP), AK, soil organic matter (OM), and electrical conductivity (EC) than non-rhizosphere soil samples (P<0.05). Rhizosphere soil samples had slightly higher TN, total phosphorus (TP), AN, and pH than non-rhizosphere soil samples, without significant differences. Bacterial diversity and abundance were higher in non-rhizosphere soil samples, while fungal diversity and abundance were greater in rhizosphere soil samples. Both rhizosphere and non-rhizosphere soil samples had more unique microbial operational taxonomic units (OTUs) than the control. Rhizosphere soil samples contained more fungal OTUs but fewer bacterial OTUs than non-rhizosphere soil samples. Dominant fungal phyla included Ascomycota, Basidiomycota, unclassified fungal phyla, and Rozellomycota, with major fungal genera comprising Candida, Paraphoma, Alternaria, unclassified fungal genera, and Penicillium. Dominant bacterial phyla included Actinobacteriota, Proteobacteria, Bacteroidota, Chloroflexi, and Acidobacteria, with key bacterial genera being Arthrobacter, Nocardioides, Streptomyces, Agromyces, and Sphingomonas. Linear discriminant analysis effect size (LEfSe) identified 212 bacterial taxa and 25 fungal taxa significantly distinguishing rhizosphere soil samples from non-rhizosphere soil samples, with Ascomycota and Proteobacteria being the key taxa. Redundancy analysis showed that OM was the main factor affecting the structure of soil microbial community, positively correlating with Basidiomycota, Acidobacteria, Chloroflexi, and unclassified fungal phyla, while negatively correlating with Ascomycota, Rozellomycota, Actinobacteriota, Proteobacteria, and Bacteroidota.Conclusion The cultivation of A. desertorum significantly increased the nutrient levels and fungal diversity and abundance in the rhizosphere soil at the southeastern edge of the Tengger Desert, contributing to soil ecosystem stability. This study offers theoretical insights into regional ecological restoration and provides a scientific basis for restoration scheme optimization and sustainable management of A. desertorum ecosystems.