A cinnamyl alcohol dehydrogenase required for sclerotial development in Sclerotinia sclerotiorum

Abstract

Sclerotial development is a vital stage in the life cycles of many fungal plant pathogens. In this study, the protein Ss-CAD, which contains three conserved domains of cinnamyl alcohol dehydrogenase (CAD), was found to be required for sclerotial development in Sclerotinia sclerotiorum . Ss-CAD was significantly upregulated during early stage of sclerotial development. In Ss-CAD- silenced strains, sclerotial development was abnormal. In these silenced strains, formation of sclerotia was delayed or sclerotia yield was reduced, whereas hyphal growth and virulence were normal. Nox1 , Nox2 , and NoxR , which encode reactive oxygen species (ROS)-generating NADPH oxidases, were downregulated in Ss-CAD -silenced strains. NoxR- silenced strains displayed similar defects during sclerotial formation as Ss-CAD -silenced strains. Treatment of Ss-CAD -silenced strains with exogenous oxidants or NADPH restored normal sclerotial development. Sclerogenesis in Ss-CAD -silenced strains could also be recovered through Nox1 overexpression. The results suggest that Ss-CAD is linked to the NADPH oxidase pathways to affect sclerotial development in S. sclerotiorum .