Assessment of the rhizosphere fungi and bacteria recruited by sugarcane during smut invasion.

Whip smut is one of the most serious and widely spread sugarcane diseases. Plant-associated microbes play various roles in conferring advantages to the host plant. Understanding the microbes associated with sugarcane roots will help develop strategies for the biocontrol of smut. Therefore, the present study explored microbe-mediated sugarcane response to smut invasion via 16S rRNA and ITS metabarcoding survey of the rhizosphere soils of resistant and susceptible sugarcane varieties. The bacterial and fungal diversity in the rhizosphere soils differed between the resistant and susceptible varieties. The bacterial genera Sphingomonas, Microcoleus_Es-Yyy1400, Marmoricola, Reyranella, Promicromonospora, Iamia, Phenylobacterium, Aridibacter, Actinophytocola, and Edaphobacter and one fungal genus Cyphellophora were found associated with smut resistance in sugarcane. Detailed analysis revealed that the majority of bacteria were beneficial, including the actinomycete Marmoricola and Iamia and Reyranella with denitrification activity. Analysis of bacterial network interaction showed that three major groups interacted during smut invasion. Meanwhile, seven of these genera appeared to interact and promote each other's growth. Finally, functional annotation based on the Functional Annotation of Prokaryotic Taxa (FAPROTAX) database predicted that the abundant bacteria are dominated by oxygenic photoautotrophy, photoautotrophy, and phototrophy functions, which may be related to smut resistance in sugarcane. The present study thus provides new insights into the dynamics of the sugarcane rhizosphere microbial community during smut invasion.