Pgmiox mediates stress response and plays a critical role for pathogenicity in Pyrenophora graminea, the agent of barley leaf stripe.

Barley leaf stripe is an important disease caused by Pyenophora graminea that affects barley yields in the world. Ascorbic acid (AsA) interacts with key elements of a complex network orchestrating plant defense mechanisms, thereby influencing the outcome of plant-pathogen interaction. Myo-inositol oxygenase (MIOX) is a pivotal enzyme involved in plants development and environmental stimuli. However, MIOX has described functions in plants but has not been characterized in fungi. In this study, we characterized the Pgmiox gene in P. graminea pathogenesis through annotated on the metabolic pathway of ascorbic acid aldehyde. Our analysis suggested that the Pgmiox protein had a typical conserved MIOX domain. Multiple alignment analysis indicated that the P. graminea MIOX orthologue clustered with MIOX proteins of Pyrenophora species. RNA interference successfully reduced transcript abundance of Pgmiox in six transformant lines compared to wild type, and the transformants were further less virulent on the host plant barley. Transformants of Pgmiox had significant reductions in vegetative growth and pathogenicity, which had increased resistance to tebuconazole and carbendazim. In addition, Pgmiox is associated with ionic, drought, osmotic, oxidative, and heavy metal stress tolerance in P. graminea. In conclusion, our findings reveal that Pgmiox may be widely utilized by fungi to enhance pathogenesis and holds significant potential for the development of durable P. graminea resistance through genetic modifications.