Potential Role of Po-milR-1 and Its Target Po-3KAT in the Growth, Development and Stress Response of Pleurotus ostreatus

Pleurotus ostreatus is an important edible mushroom, and its growth and development are affected by genetic and epigenetic mechanisms. miRNAs play an important role in fungal epigenetic mechanisms. In previous studies, Po-3KAT was identified as a candidate target of Po-milR-1, and its product was a substrate for ergosterol synthesis. However, the potential relationship between Po-milR-1 and Po-3KAT has not been studied in P. ostreatus. Therefore, this study aims to explore the potential role of Po-milR-1 and Po-3KAT in P. ostreatus. By integrating the Po-milR-1 interference vector into the genome of P. ostreatus, it was found that the mycelial growth rate was accelerated and the fruiting body phenotype changed in the Po-STTM transformants. The expression analysis during development suggested an inverse expression pattern between Po-milR-1 and Po-3KAT. The analysis of qRT-PCR and HPLC showed that 2 mmol/L H2O2 promoted the expression of Po-3KAT, and the content of ergosterol increased to 1.17-fold, while 5 mmol/L H2O2 inhibited the expression of Po-3KAT, and the content of ergosterol decreased to 0.82-fold. In contrast to oxidative stress, 100 mmol/L and 250 mmol/L salt stress inhibited the expression of Po-3KAT, and the content of ergosterol decreased to 0.87-fold and 0.94-fold, respectively. These results suggest that Po-milR-1 and Po-3KAT may be involved in the regulation of growth, development, and stress responses in P. ostreatus, and may be associated with the change in ergosterol content.