GTPase Rho1 regulates the expression of xyl3 and laccase genes in Fusarium oxysporum.

The Rho1 protein is a GTPase that participates in cell wall biogenesis. We analyzed the transcript levels of laccase genes (lccl, lcc2, lcc3, lcc4, lcc5, and lcc9), and a xylanase gene (xyl3) in Fusarium oxysporum f. sp. lycopersici strain 4287 (wild type) and two mutant strains; rhol::hyg that lacks a functional Rho1, and rho1::hyg + rho1 (G14V) that has a constitutively active Rho1. The transcript levels of lcc2, lcc3, lcc5, and xyl3 differed among the three strains, but those of lcc1 and lcc9 did not. Xylanase activities were higher in rho1::hyg than in both the wild type and rho1::hyg + rho1 (G14V) . Laccase activities were significantly higher in the two mutants than in the wild type. Rho1 thus plays a role in regulating xyl3, lcc2, lcc3, and lcc5 at the transcriptional and/or translational level.