Light and abiotic stress both strongly modulate plant growth and development. However, the effect of light-responsive factors on growth and abiotic stress responses in wheat (Triticum aestivum) is unknown. G–box binding factors (GBFs) are blue light-specific components, but their function in abiotic stress responses has not been studied. Here we identified a wheatGBF1gene that mediated both the blue light- and abiotic stress-responsive signaling pathways.TaGBF1was inducible by blue light, salt and exposure to abscisic acid (ABA). TaGBF1 interacted with a G–box light-responsive elementin vitroand promoted a blue-light response in wheat andAradidopsis thaliana. BothTaGBF1over-expression in wheat and its heterologous expression inA. thalianaheighten sensitivity to salinity and ABA, but its knockdown in wheat conferred resistance to high salinity and ABA. The expression ofAtABI5, a key component of the ABA signaling pathway inA. thaliana, and its homologWabi5in wheat was increased by transgenic expression ofTaGBF1. The hypersensitivity to salt and ABA caused byTaGBF1was not observed in theabi5mutant background, showing that ABI5 is the mediator in TaGBF1-induced abiotic stress responses. However, the hypersensitivity to salt conferred byTaGBF1is not dependent on light. This suggests that TaGBF1 is a common component of blue light- and abiotic stress-responsive signaling pathways.Significance Statement
G-box binding factors (GBFs) are blue-light specific components, but their function in abiotic stress response has not been studied. Here, we show that a wheat GBF both promoted the blue-light response and enhanced salt sensitivity by inducing expression of ABI5, a crucial factor in the ABA signalling pathway.