Region-based differences in the diversity and abundance of fungal community in cotton soils

Abstract

Fungi are ubiquitous and account for more than 60% of microbial abundance in Australian soils including those under intensive cotton cropping. Plant associated fungal communities not only assist with crop nutrition but can also function as an important line of defence against fungal pathogens e.g. species-rich communities are more resistant to pathogen invasions. Their many roles in ecosystem processes, both beneficial and deleterious, have been identified but the determinants of their diversity and abundance in cotton soils as influenced by the biographical habitat are poorly understood. Surface 0-10 cm soils from farmer fields, monitoring cotton performance and disease incidence in 5 cotton growing regions in Queensland and New South Wales, collected during 2016 cotton season were analysed for the genetic diversity (ITS region sequencing) and abundance (qPCR) of fungi. Samples were also analysed for microbial catabolic diversity, microbial biomass and soil chemical properties.
Briefly, Ascomycota are the most dominant group of fungi in all the soils accounting for 68 to 78% of total fungi followed by Basidiomycota (12 to 19%) and Zygomycota (1-9%). Fungal genera belonging to the Classes Sordariomycetes (43 to 53%), Agaricomycetes (9-21%) and Dothideomycetes (5 to 17%) were the major groups that showed distinct differences between locations. Members of Glomeromycetes fungi (mycorrhizal fungi) accounted for 2.2%), probably due to the P fertilization in cotton crops. Results also indicated significant differences in the abundance & diversity of fungal community, e.g. Shannon diversity index was lower in the soils from St. George and Emerald regions compared to that in the Darling Downs and Namoi region soils. Overall, these results suggest that soil ecological and environmental factors and management-related filtering processes related to substrate quality and availability play a significant role in shaping fungal communities and their functionality in cotton soils.