AUTHOR=Sun Shuquan , Deng Yizhen , Cai Enping , Yan Meixin , Li Lingyu , Chen Baoshan , Chang Changqing , Jiang Zide 

TITLE=The Farnesyltransferase β-Subunit Ram1 Regulates Sporisorium scitamineum Mating, Pathogenicity and Cell Wall Integrity

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00976

DOI=10.3389/fmicb.2019.00976

ISSN=1664-302X

ABSTRACT=<p>The basidiomycetous fungus <italic>Sporisorium scitamineum</italic> causes a serious sugarcane smut disease in major sugarcane growing areas. Sexual mating is essential for infection to the host; however, its underlying molecular mechanism has not been fully studied. In this study, we identified a conserved farnesyltransferase (FTase) β subunit Ram1 in <italic>S. scitamineum</italic>. The <italic>ram1</italic>Δ mutant displayed significantly reduced mating/filamentation, thus of weak pathogenicity to the host cane. The <italic>ram1</italic>Δ mutant sporidia showed more tolerant toward cell wall stressor Congo red compared to that of the wild-type. Transcriptional profiling showed that Congo red treatment resulted in notable up-regulation of the core genes involving in cell wall integrity pathway in <italic>ram1</italic>Δ sporidia compared with that of WT, indicating that Ram1 may be involved in cell wall integrity regulation. In yeast the heterodimeric FTase is responsible for post-translational modification of Ras (small G protein) and a-factor (pheromone). We also identified and characterized two conserved Ras proteins, Ras1 and Ras2, respectively, and a <italic>MAT-1</italic> pheromone precursor Mfa1. The <italic>ras1</italic>Δ, <italic>ras2</italic>Δ and <italic>mfa1</italic>Δ mutants all displayed reduced mating/filamentation similar as the <italic>ram1</italic>Δ mutant. However, both <italic>ras1</italic>Δ and <italic>ras2</italic>Δ mutants were hypersensitive to Congo red while the <italic>mfa1</italic>Δ mutant was the same as wild-type. Overall our study displayed that <italic>RAM1</italic> plays an essential role in <italic>S. scitamineum</italic> mating/filamentation, pathogenicity, and cell wall stability.</p>