关键词: 大丽轮枝菌, 棉花黄萎病, 入侵, 棉田土壤, 真菌群落, 高通量测序

Abstract:

【Objective】 Fungus is an important part of soil microbial system, which can obviously indicate the change of soil environment. The objective of this study is to analyze the characteristics of fungal communities in cotton-field soil with different incidences of Verticillium wilt, determine the effect of Verticillium dahliae on the diversity and community structures of fungi in cotton fields, and to reveal the ecological function of fungi community in soil during the occurrence of Verticillium wilt.【Method】 Cotton fields with different incidences of Verticillium wilt in Aksu and Shihezi, and artificially inoculated cotton field in Korla were chosen as research objects. Six soil samples collected from serious diseased fields in Aksu (AD), Korla (KD), Shihezi (SD) and their controls were tested, respectively. Illumina Hiseq high-throughput sequencing technique was used to study the diversity and community structure of fungi in soil. The correlation between fungal community structure and soil nutrients was clarified with redundancy analysis (RDA).【Result】 At the similarity level of 97%, the OTU number, Chao1 and Ace richness index of fungi in AD and SD samples were higher than those of ACK and SCK samples, while the Simpson index was lower than that of control. There was no significant difference in OTU number, Chao1 and Ace richness index and Simpson index between artificially inoculated KD and control KCK samples. NMDS analysis showed that the soil samples of AD and SD had spatial tendency first and then temporal tendency, while the soil samples in Korla had temporal tendency first and then spatial tendency. In terms of community composition, at the phylum level, the abundance of Ascomycota in soil was dominant, followed by Basidiomycota and Mortierellomycota. The abundance differences of the three phylum groups between KD and KCK samples and between SD and SCK samples were relatively small, while those between AD and ACK samples were relatively larger. At the genus level, Sporobolomyces had the highest abundance, and the abundances of both Sporobolomyces and Mortierella were higher than those of the control in the soils of seriously diseased field in different regions, but Wardomyces was lower than that of the control. In addition, the abundance of Pyrenochaetopsis, Microdochium and Fusarium in AD samples was lower than that of ACK samples, while the abundance of these three genera in SD samples was higher than that of SCK samples. The significant difference analysis among groups indicated that the significant difference markers in Korla and Shihezi soils were mainly concentrated in the seriously diseased fields, while in Aksu soils they were mainly concentrated in disease-free fields. Correlation and RDA analysis showed that soil organic matter and total nitrogen content were positively correlated with OTU number and abundance of fungi, but had low correlation with Simpson index. The pH, total phosphorus and total potassium were positively correlated with Simpson index, while total salt was negatively correlated with Simpson index.【Conclusion】 The OTU number and abundance of fungi in the soil of natural seriously diseased cotton fields are higher than those in the control, but the diversity of fungi is low. In the short term, artificial inoculation does not have significant effects on the abundance, diversity and community structure of the fungi in the soil. The diversity, abundance and composition of fungi in soil are significantly affected by the indexes of organic matter, total nitrogen and salt content. The sampling period also has significant effects on the community structure of fungi in soil.

Key words: Verticillium dahliae, cotton Verticillium wilt, invasion, cotton-field soil, fungal community, high-throughput sequencing