不同根腐病发病率青稞农田根际土壤真菌多样性特征及差异

Characteristics and disparities of fungal diversity in rhizosphere soil of naked barley from fields with different root rot incidences

摘要:

目的 明确不同根腐病发病率青稞农田根际土壤真菌多样性特征及差异，为其精准、高效防控提供理论依据。方法 采集青稞农田内健康及根腐病发病率为5%、10%、15%、20%的根际土壤样品，对真菌18S rRNA基因进行扩增，采用Illumina-MiSeq平台进行高通量测序。数据经质控、分类及注释后，从不同角度及分类水平对物种多样性进行分析。结果 健康与发病率为5%的样本真菌多样性最为丰富，发病率为10%的样本最低。共现网络分析发现，健康与发病率为5%的样本内物种间相互作用更为复杂。发病率越高，子囊菌门(Ascomycota)相对丰度越低，而担子菌门(Basidiomycota)、球囊菌门(Glomeromycota)相对丰度越高。优势真菌集中于伞菌纲(Agaricomycetes)、壶菌纲(Chytridiomycetes)、粪壳菌纲(Sordariomycetes)等。在各样本中，平均相对丰度较高的菌群分布差异更为显著。健康样本中散囊菌目(Eurotiales)相对丰度最高，球囊霉目(Glomerales)相对丰度最低；发病样本中则相反。裸囊菌科(Arthrodermataceae)显著富集于健康样本，粪壳菌科(Sordariaceae)、粘毛菌科(Myxotrichaceae)、油壶菌科(Olpidiaceae)分别显著富集于发病率为10%、15%、20%的样本。在属、种水平上，健康与发病率为5%的样本优势真菌群落构成相近，发病率为10%、15%、20%的样本更为相近。FUNGuild功能预测分析发现，发病率越高，植物病原菌相对丰度越低，而土壤腐生菌相对丰度越高。结论 青稞根腐病的发生蔓延与根际土壤真菌群落结构失衡密切相关，青稞根腐病的精准防控应考虑调控并维持根际优势真菌类群的丰度平衡。

Abstract:

Objective To delineate the fungal diversity characteristics and disparities in the rhizosphere soil of naked barley from fields exhibiting different root rot incidences, thereby informing targeted and effective disease management strategies.Methods Rhizosphere soil samples of naked barley were collected from the healthy field and the fields with root rot incidences of 5%, 10%, 15%, and 20%, respectively. The 18S rRNA gene of fungi from the samples was amplified, and high-throughput sequencing was conducted on the Illumina-MiSeq platform. Following quality control, classification, and annotation, the data were analyzed for fungal diversity from various perspectives and taxonomic levels.Results The healthy sample and the sample with the root rot incidence of 5% had the highest fungal diversity, while the sample with the incidence of 10% exhibited the lowest diversity. Additionally, co-occurrence network analysis revealed more complex species interactions in the healthy sample and the sample with the incidence of 5%. The root rot incidence had a negative correlation with the relative abundance of Ascomycota but a positive correlation with the relative abundance of Basidiomycota and Glomeromycota. Dominant fungal classes were Agaricomycetes, Chytridiomycetes, and Sordariomycetes. Significant variations in the distribution of fungal groups with high average relative abundance were noted across samples. Specially, the healthy sample had the highest relative abundance of Eurotiales and the lowest relative abundance of Glomerales, which were converse in diseased samples. Arthrodermataceae was significantly enriched in the healthy sample, while Sordariaceae, Myxotrichaceae, and Olpidiaceae were preferentially associated with the samples exhibiting incidences of 10%, 15%, and 20%, respectively. At the genus and species levels, the composition of dominant fungal communities in the healthy sample and the sample with the incidence of 5% was similar, and it was similar in the samples with incidences of 10%, 15%, and 20%. FUNGuild predicted a decrease in the relative abundance of plant pathogens and an increase in the relative abundance of saprotrophs with the increase in disease incidence.Conclusion The progression of naked barley root rot is intricately linked to the disruption of the equilibrium within the rhizosphere fungal community. In the context of precision management of naked barley root rot, it is imperative to regulate and sustain the balance of the abundance of dominant fungal taxa in the rhizosphere.