The Tin2 effector determines the pathogenic lifestyle in smut fungi
S. TANAKA (1), R. Kahmann (1) (1) Max Planck Institute for Terrestrial Microbiology, Germany

The secreted Tin2 effector protein of the corn smut fungus Ustilago maydis is responsible for anthocyanin induction. Anthocyanin induction by Tin2 is thought to rewire metabolic precursors away from the lignin pathway to promote virulence, resulting in the effective colonization of vascular bundles. On the other hand, the related smut fungus S. reilianum f.sp. zeae which causes head smut disease of corn does not induce anthocyanin, although the genome of S. reilianum encodes a Tin2 homologue (SrTin2). We have now shown that Δtin2 strain of U. maydis expressing SrTin2 could not induce anthocyanin and SrTin2 does not interact with the maize protein kinase ZmTTK1, which is stabilized by Tin2 of U. maydis for anthocyanin induction. This indicates that SrTin2 has lost the ability for anthocyanin induction. On the other hand, S. reilianum f.sp. zeae expressing Tin2 of U. maydis could fully induce anthocyanin in the infected maize leaves. Microscopic observation revealed that these strains show more effective colonization and growth along with the vascular bundles compared to the wild-type S. reilianum f.sp. zeae. These results suggest that, through the course of evolution, U. maydis Tin2 has specifically acquired the function for anthocyanin induction to promote virulence and conceivably contributes to tumor formation.

Abstract Number: P9-310
Session Type: Poster