Activation of Ustilaginoidin Biosynthesis Gene in Albino Strain LN02 Influences Development, Stress Responses, and Inhibition of Rice Seed Germination.

(anamorph: ) is the pathogen of rice false smut (RFS), which is a destructive rice fungal disease. The albino strain LN02 is a natural white-phenotype mutant of due to its incapability to produce toxic ustilaginoidins. In this study, three strains including the normal strain P1, albino strain LN02, and complemented strain -1 of the LN02 strain were employed to investigate the activation of the ustilaginoidin biosynthesis gene in the albino strain LN02 to influence sporulation, conidia germination, pigment production, stress responses, and the inhibition of rice seed germination. The activation of the ustilaginoidin biosynthesis gene increased fungal tolerances to NaCl-induced osmotic stress, Congo-red-induced cell wall stress, SDS-induced cell membrane stress, and HO-induced oxidative stress. The activation of also increased sporulation, conidia germination, pigment production, and the inhibition of rice seed germination. In addition, the activation of was able to increase the mycelial growth of the albino strain LN02 at 23 °C and a pH from 5.5 to 7.5. The findings help in understanding the effects of the activation of in albino strain LN02 on development, pigment production, stress responses, and the inhibition of rice seed germination by controlling ustilaginoidin biosynthesis.