Fungi diversity analysis of rhizosphere under drought conditions in cotton

Abstract

Plant rhizosphere microorganisms play important roles in plant growth and the adaptability of plants to adverse environmental stresses. In this study, cotton rhizosphere fungal communities were analyzed under drought conditions, aiming to explore the effects of drought stress on the diversity and community structures of cotton rhizosphere fungi, and to provide a theoretical basis for improving cotton water use efficiency by using beneficial microorganisms. Drought stress was applied to upland cotton (Gossypium hirsutum cv. Jin 668) at flowering stage (SDP), while the soil without plants was also subjected to drought (SOPD). Simultaneously, the plants (SPN) and pots without plants (SNPN) regularly watered were used as controls. The soil samples were collected, the microbial DNA was isolated, and Illumina Miseq was conducted for a high-throughput sequencing of fungi ITS1 regions to study the diversity of the rhizosphere fungal communities. As a result, a total of 970 OTUs were identified, and the numbers of fungal OTUs in the samples of SNPN, SOPD, SPN, and SDP were 481, 528, 743, and 752, respectively, among which 288 OTUs were shared by all samples. The OTUs were classified to different levels of phyla, class, order, family, and genus of fungi. The rhizosphere fungal community of cotton was predominantly consisted of the phyla Ascomycota (82.70%) and Basidiomycota (10.15%). The abundance of Sordariomycetes, Sordariales, and Chaetomiaceae decreased, while the abundance of Eurotiales, Trichocomaceae, Aspergillus, and Penicillum increased significantly under drought stress. Moreover, the diversity of fungal community in the soil with cotton plants significantly higher than that in the soil without cotton plants. Meanwhile, the fungi community structures of SPN and SDP resembling each other and differing greatly from SNPN and SOPD. These results revealed that the cotton rhizosphere had a rich pool of fungal communities, and drought stress had a significant effect on the abundances and diversity of fungi in cotton rhizosphere. This study provided new insights for the researches of improving drought tolerance of cotton in terms of soil microorganisms.