A color-selectable and site-specific integrative transformation system for gene expression studies in the dematiaceous fungus Wangiella (Exophiala) dermatitidis.

To explore potential virulence factors in the dematiaceous (melanized) fungus Wangiella dermatitidis, we established a gene expression system with properties of homologous transformation and color identification. Using a polyketide synthase gene (WdPKS1) fragment for targeting, we found that 52% of transformants became albinos easily distinguishable from nonspecific transformants. Southern analysis confirmed that the integrations were at the WdPKS1 locus, which however did not affect transformant growth. With a heterologous promoter, P-glaA, enhanced expression of lacZ was found at 37 degrees C. Our results indicated that this system allows the efficient production of isogenic strains for gene function analysis in W. dermatitidis.