Characterization and overexpression of RHO1 from Cryptococcus laurentii ZJU10 activates CWI signaling pathway on enhancing the inhibition of blue mold on pears

Results from this study explored the inhibitory effect of RHO1 gene (GenBank accession number KY859864) from the antagonistic yeast, Cryptococcus laurentii ZJU10, on the control of Penicillium expansum in pear fruit and its possible mechanism involved. The RHO1 gene was successfully cloned and overexpressed in Saccharomyces cerevisiae. Sequence analysis showed high similarity with Rho family proteins, implying a primary role of Rho1 in the cell wall integrity (CWI) signaling pathway. Gene expression of RHO1 and other five CWI-related genes (including Pkc1, Rlm1, Fks1, Fks2 and Chs3) were significant up-regulated in the treatment of SC/Rho1-induced strain (Saccharomyces cerevisiae transformed with RHO1 and induced by galactose). Meanwhile, SC/Rho1-induced treatment reduced about 61.5% of disease incidence and almost 5-times lower lesion diameter compared to the control. In addition, the growth of transformed strains was slightly lower in contrast to the wild Saccharomyces cerevisiae and the induction of fruit resistance was significantly enhanced, which was tightly linked with triggering stronger host defensive responses by priming activation. This is the first study that Rho1 has a potential function of suppressing fungal disease in harvested fruit by activating CWI signaling pathway and indicates an alternative strategy for postharvest disease management.