De novo transcriptome analysis of Rhizoctonia solani AG1 IA strain early invasion in Zoysia japonica root Transcriptome

Zoysia japonica brown spot was caused by necrotrophic fungus Rhizoctonia solani invasion, which led to severe financial loss in city lawn and golf ground maintenance. However, little was known about the molecular mechanism of Rhizoctonia solani pathogenicity in Zoysia japonica. In this study we examined interaction between Rhizoctonia solani AG1 IA strain and Zoysia japonica cultivar “Zenith” root by cell ultra-structure analysis, pathogenesis-related proteins assay and transcriptome analysis to explore molecular clues for AG1 IA strain pathogenicity in Zoysia japonica. That no obvious cell structure damage found in infected roots and most pathogenesis-related protein activities in roots showing a downward trend especially in 36h post inoculation exhibits AG1 IA strain stealthy invasion character. Up-regulated fungal resistance related unigenes of “Zenith” root were involved in ligin biosynthesis, phytoalexin synthesis, oxidative burst, wax biosynthesis, while two down-regulated unigenes encoding leucine-rich repeat receptor protein kinase and subtilisin-like protease might be important for host-derived signal perception and result in AG1 IA strain invasion vulnerable root. Up-regulated unigenes of AG1 IA strain participating in signal transduction, secondary metabolites biosynthesis transport and catabolism and amino acid transport and metabolism shows its delicate invasion mechanisms in “Zenith” root cell wall degration, which is similar to rice sheath blight symptome. Interestingly, rare expressing unigenes encoding cutinases in sheath blight symptome were found in Zoysia japonica brown spot. This research uncovered transcriptional profiling during the early phase interaction between Rhizoctonia solani AG1 IA strain and Zoysia japonica, and will greatly help identify key pathogenicity of AG1 IA strain.