Characterization and Variation of the Rhizosphere Fungal Community Structure of Cultivated Tetraploid Cotton

AbstractRhizosphere fungal communities exert important influential forces on plant growth and health. However, information on the dynamics of the rhizosphere fungal community structure of the worldwide economic crop, cotton (Gossypium spp.), is limited. Next-generation sequencing of nuclear ribosomal internal transcribed spacer-1 (ITS1) was used to characterize the rhizosphere fungal communities of worldwide cultivated tetraploid cotton using G. hirsutum cv. TM-1 (upland cotton) and G. barbadense cv. Hai 7124 (island cotton). Plants were grown in field soil (FS) that had been continuously cropped with cotton and nutrient-rich soil (NS) that had not been cropped. Fungal species richness, diversity, and community composition were analyzed and compared among soil resources, cotton genotypes, and developmental stages. We found that the fungal community structure between the rhizosphere and bulk soil of cotton were different and the rhizosphere fungal communities were significantly varied between FS and NS. These results suggest that cotton rhizosphere fungal community structure variation was primarily determined by the interaction of cotton roots with different soil resources. We also found that the community composition of cotton rhizosphere fungi varied significantly during different developmental stages, suggesting that developmental stages were also important factors in the dynamics of rhizosphere fungal communities for the varying dominant fungal genera of the rhizosphere. In addition, we also observed that fungal pathogens were clearly increased at certain developmental stages, suggesting a higher infection rate and a high incidence of corresponding soil-borne disease in each stage. This research illustrates the characteristics of cotton rhizosphere fungal communities and provides important information for understanding the potential influences of rhizosphere fungal communities on cotton growth and health.