Two cotton Cys2/His2-type zinc-finger proteins, GhDi19-1 and GhDi19-2, are involved in plant response to salt/drought stress and abscisic acid signaling

Cotton (Gossypium hirsutum) often encounters abiotic stress such as drought and high salinity during its development, and its productivity is significantly limited by those adverse factors. To investigate the molecular adaptation mechanisms of this plant species to abiotic stress, we identified two genes encoding Di19-like Cys2/His2 zinc-finger proteins in cotton. GFP fluorescence assay demonstrated that GhDi19-1 and GhDi19-2 are two nuclear-localized proteins. Quantitative RT-PCR and Northern blot analyses revealed that mRNA accumulation of both GhDi19-1 and GhDi19-2 was significantly promoted by salinity and drought. Expression of GUS gene driven by the GhDi19-1 and GhDi19-2 promoters, respectively, was intensively induced in cotyledons under NaCl and mannitol stresses. Overexpression of GhDi19-1 and GhDi19-2 in Arabidopsis resulted in the seedlings displaying hypersensitivity to high salinity and abscisic acid (ABA). Seed germination and seedling growth of the transgenic Arabidopsis were dramatically inhibited by salinity and ABA, compared with wild type. In addition, expression levels of the ABA-responsive genes ABF3, ABF4, ABI5 and KIN1 were also remarkably altered in the transgenic plants under ABA treatment. Collectively, our results suggested that both GhDi19-1 and GhDi19-2 may be involved in response to salt/drought stress and ABA signaling during early stages of plant development.