Protocol for conditional gene expression in Magnaporthe oryzae via fungal nitrate reductase promoter replacement

Functional genomic studies rely on controlled gene expression, which is challenging for essential genes or those active only under specific conditions. We provide a protocol for generating Magnaporthe oryzae (synonym of Pyricularia oryzae) with conditional BUF1 gene expression. We describe steps for using targeted promoter replacement to substitute the native BUF1 promoter with the nitrogen-responsive promoter. This approach enables nitrogen source-dependent control of expression in M. oryzae, leading to observable pigmentation changes that facilitate easy phenotypic screening.