The histidine phosphotransfer AHP4 plays a negative role inArabidopsisplant response to drought

Abstract

Cytokinins play an important role in plant stress responses via a multistep signaling pathway, involving the histidine phosphotransfer proteins (HPs). Here, the AHP4 possesses a negative regulatory role in drought response in Arabidopsis thaliana as evidenced by higher survival rates of ahp4 than wild-type (WT) plants under drought, and the down-regulated AHP4 expression in WT during dehydration. Transcriptome analysis of ahp4 and WT plants revealed AHP4-mediated expression of dehydration- and/or abscisic acid (ABA)-responsive genes important for plant drought acclimation. ahp4 plants showed increased wax crystal accumulation in stems, thicker cuticles in leaves, greater sensitivity to exogenous ABA, narrower stomatal apertures, higher leaf temperatures during dehydration, and longer root length under osmotic stress. Additionally, ahp4 plants showed greater photosynthetic efficiency, lower levels of reactive oxygen species, reduced electrolyte leakage and lipid peroxidation, and increased anthocyanin contents under drought. Findings could make editing of AHP4 a promising approach for generating drought-tolerant crops.