A novel maize F-bZIP member, ZmbZIP76, functions as a positive regulator in ABA-mediated abiotic stress tolerance by binding to ACGT-containing elements

Abstract

The group F-bZIP transcription factors (TFs) in Arabidopsis are involved in nutrient deficiency or salt stress responses. Nevertheless, our learning about the functions of group F-bZIP genes in maize remains limited. Here, we cloned a new F-bZIP gene (ZmbZIP76) from maize inbred line He344. The expression of ZmbZIP76 in maize was dramatically induced by high salt, osmotic stress and abscisic acid. Accordingly, overexpression of ZmbZIP76 increased tolerance of transgenic plants to salt and osmotic stress. In addition, ZmbZIP76 functions as a nuclear transcription factor and upregulates the expression of a range of abiotic stress-responsive genes by binding to the ACGT-containing elements, leading to enhanced reactive oxygen species (ROS) scavenging capability, increased abscisic acid level, proline content, and ratio of K⁺/Na⁺, reduced water loss rate, and membrane damage. These physiological changes caused by ZmbZIP76 ultimately enhanced tolerance of transgenic plants to salt and osmotic stress.

Keywords: ABA; BZIP transcription factor; Gene expression regulation; Maize; ROS; Stress resistance.