ZxABCG11 from the xerophyte Zygophyllum xanthoxylum enhances drought tolerance in Arabidopsis thaliana through modulating cuticular wax accumulation

Abstract

Cuticular waxes, a waterproofing hydrophobic barrier that coats the aerial surfaces of all terrestrial plants, protects plants from various environmental stresses, particularly drought stress. The molecular basis of cuticular wax deposition in xerophytes (e.g. desert plants), including transport mechanisms of waxes to the cell wall, is poorly understood. Here, ZxABCG11 encoding an ATP binding cassette (ABC) transporter was isolated from the xerophyte Zygophyllum xanthoxylum, since we found it was predominantly expressed in young leaves and induced by salt, drought, heat, and combined drought and heat stresses. To ascertain the function of ZxABCG11, we introduced ZxABCG11 into Arabidopsis thaliana and found an increased abundance of cuticular wax on stems and leaves of the transgenic plants, which also exhibited a thickened cuticle and reduced cuticle permeability. Transcript expression analysis revealed that many genes related to wax biosynthesis and transport were up-regulated in these ZxABCG11 transgenic plants. Furthermore, compared with wild type Arabidopsis, ZxABCG11 transgenic plants displayed a higher biomass and survival rate under drought conditions. Taken together, we propose that the expression of ZxABCG11 in Arabidopsis promotes cuticular wax accumulation and thicker cuticle formation, thereby enhancing drought tolerance.