Bifunctional trehalase FsTreA coordinates intracellular mobilization and extracellular utilization of trehalose to modulate virulence in <i>Fusarium sacchari</i>

ABSTRACT Fusarium sacchari causes devastating Sugarcane Pokkah Boeng Disease by infecting tissues through conidia that enter via micro-wounds or stomata on the leaf surface, making conidial germination a critical step in its pathogenicity. Here, we identified a trehalase, FsTreA, which contains not only the essential trehalase structural domain characteristic of neutral trehalases but also features an N-terminal signal peptide. FsTreA exhibits the highest transcriptional level among all trehalases during conidial germination. Disruption of FsTreA significantly elevated intracellular trehalose accumulation in conidia, confirming its role in intracellular mobilization. However, ΔFsTreA showed accelerated trehalose mobilization rates during germination, coinciding with enhanced conidial germination, and increased conidial yield. This was attributed to functional compensation by two other trehalases, FsNth1 and FsAth1. Furthermore, we found that FsTreA predominantly localizes to the cell surface and possesses the ability to mobilize extracellular trehalose. Moreover, the virulence of FsTreA mutant strain was positively correlated with the capability for extracellular trehalose mobilization. In conclusion, our results demonstrate that the bifunctional trehalase FsTreA coordinates intracellular and extracellular trehalose utilization to modulate virulence in F. sacchari . IMPORTANCE Sugarcane Pokkah Boeng Disease, caused by Fusarium sacchari , poses a severe threat to global sugarcane production. This study represents the first identification of the bifunctional trehalase FsTreA in F. sacchari , which breaks the traditional dichotomous classification framework of traditional fungal trehalases. FsTreA harbors both the GH37 catalytic domain characteristic of neutral trehalases and an N-terminal signal peptide conferring the secretory trait of acid trehalases. This enzyme participates in intracellular trehalose mobilization and is simultaneously secreted extracellularly to hijack host-derived trehalose as a carbon source, constituting a distinctive infection strategy that provides new insights into host-pathogen interaction mechanisms. These findings advance the theoretical understanding of fungal metabolic regulation, holding significant scientific and practical value for safeguarding the security of the global sugarcane industry.