Three Genes Related to Trehalose Metabolism Affect Sclerotial Development of Rhizoctonia solani AG-1 IA,Causal Agent of Rice Sheath Blight

Trehalose metabolism is related to the sclerotial development of Rhizoctonia solani AG-1 IA,the causal agent of rice sheath blight(RSB).Here,we further elucidated the functions of three genes Rstre,Rstps1 and Rstpp that encode three key enzymes trehalase(TRE),alpha,alpha-trehalosephosphate synthase(TPS1)and trehalose 6-phosphate phosphatase(TPP)in the sclerotial development of R.solani AG-1 IA.Due to the lack of a stable genetic transformation system for R.solani,the heterologous expression of these three genes in Pichia pastoris GS115 was performed.The results showed that reactive oxygen species(ROS)contents and enzyme activities in R.solani decreased significantly in the treatments of the fermentation broths of Rstps1 and Rstpp transformants,and that in the treatment of the fermentation broth of Rstre transformant visibly increased.Furthermore,the fermentation broths of the transformants of all the three genes were added to potato dextrose agar(PDA)medium for the cultivation of R.solani,as a result,the dry weight of sclerotia in each PDA plate containing the fermentation broths of Rstps1 and Rstpp transformants significantly increased compared with the control,and that of Rstre transformant obviously decreased.Finally,178 proteins were found to interact with RSTPS1,and 16 of them were associated with ROS.Taken together,the findings suggest that all these three genes related to trehalose metabolism play important roles in the sclerotial development of R.solani AG-1 IA,and can be used as new targets for the development of novel high-efficiency fungicides for the controlling of RSB.

Atmospheric humidity regulates same-sex mating in Candida albicans through the trehalose and osmotic signaling pathways

Sexual reproduction is prevalent in eukaryotic organisms and plays a critical role in the evolution of new traits and in the generation of genetic diversity.Environmental factors often have a direct impact on the occurrence and frequency of sexual reproduction in fungi.The regulatory effects of atmospheric relative humidity(RH)on sexual reproduction and pathogenesis in plant fungal pathogens and in soil fungi have been extensively investigated.However,the knowledge of how RH regulates the lifecycles of human fungal pathogens is limited.In this study,we report that low atmospheric RH promotes the development of mating projections and same-sex(homothallic)mating in the human fungal pathogen Candida albicans.Low RH causes water loss in C.albicans cells,which results in osmotic stress and the generation of intracellular reactive oxygen species(ROS)and trehalose.The water transporting aquaporin Aqy1,and the G-protein coupled receptor Gpr1 function as cell surface sensors of changes in atmospheric humidity.Perturbation of the trehalose metabolic pathway by inactivating trehalose synthase or trehalase promotes same-sex mating in C.albicans by increasing osmotic or ROS stresses,respectively.Intracellular trehalose and ROS signal the Hog1-osmotic and Hsf1-Hsp90 signaling pathways to regulate the mating response.We,therefore,propose that the cell surface sensors Aqy1 and Gpr1,intracellular trehalose and ROS,and the Hog1-osmotic and Hsf1-Hsp90 signaling pathways function coordinately to regulate sexual mating in response to low atmospheric RH conditions in C.albicans.

A Single Active Trehalose-6-P Synthase （TPS） and a Family of Putative Regulatory TPS-Like Proteins in Arabidopsis

Higher plants typically do not produce trehalose in large amounts, but their genome sequences reveal large families of putative trehalose metabolism enzymes. An important regulatory role in plant growth and development is also emerging for the metabolic intermediate trehalose-6-P （T6P）. Here, we present an update on Arabidopsis trehalose me- tabolism and a resource for further detailed analyses. In addition, we provide evidence that Arabidop$is encodes a single trehalose-6-P synthase （TPS） next to a family of catalytically inactive TPS-like proteins that might fulfill specific regulatory functions in actively growing tissues.