GhHB12 negatively regulates abiotic stress tolerance in Arabidopsis and cotton

Homeodomain-leucine zipper (HD-ZIP) is a plant-specific transcription factor family that in particularly important in plant development and stress tolerance. Our previous studies identified a cotton (Gossypium hirsutum) HD-ZIP subfamily I gene (GhHB12), which was induced by abscisic acid (ABA), methyl jasmonate (MeJA), salinity stress, and Verticillillm dahliae infection. Moreover, it regulated the cotton resistance to V. dahliae, development of its architecture, and flowering time. The present study reports that GhHB12 can be induced by polyethylene glycol 6000 (PEG-6000). Overexpression of GhHB12 in cotton and Arabidopsis resulted in decreased sensitivity to ABA and decreased salt/drought tolerance by suppressing the expressions of ABA-responsive genes and stress-related genes (ABI2, DREB2A, RD29A, RD22, RD26, RD28, SOS1, SOS2, NHX1, and HKT1). Downregulation of GhHB12 increases the tolerance to abiotic stress in cotton. Additionally, an expansion of GhHB12 homologous genes was found in G. hirsutum. Thus, GhHB12 and homologous genes can be simultaneously edited by the CRISPR/Cas9 genome editing system to generate early maturing cotton lines with strong environmental adaptability.