Overexpressing ZOS7 confers drought tolerance through mediating stomatal density and wax crystal deposition in rice

Abstract

Abstract The Cys2/His2-type zinc finger proteins have been implicated in different cellular processes involved in plant development and abiotic stress responses. Our previous study identified a drought-responsive zinc finger protein gene ZOS7 with high expression in Shanlan upland rice line possessing drought tolerance. In this study, we further found that overexpressing ZOS7 induces up to eudicots 30% increase in biomass together with 14% increase in yield relative to WT under moderate drought stress (DS) in the field. Stomatal density was increased 33% in ZOS7 knockout line with 12% water loss compared to WT exposed to DS. Transcriptome and qPCR analysis reveal significant increase in the expression of genes related to stomatal density and wax biosynthetic process. We observed that ZOS7 could bind to the C2H2 binding motif of a wax biosynthetic gene, CER4, resulting in co-transcriptional activation of CER4 and its a chaperone expression, MYB60. Interestingly, MYB60 but not ZOS7 could target to the W-box motif of a STOMAGEN like gene, EPFL9, leading to its transcriptional suppression. We hence concluded that ZOS7 and MYB60 forms a combined module that confers to drought tolerance through regulating stomatal density and wax biosynthetic process. We highlighted the importance of potential use of ZOS7-MYB60 towards drought molecular breeding in rice in the field.