HaNAC146 from sunflower overexpression enhances plant growth and stress tolerance.

Key message: This study mined a gene, HaNAC146, holds promise as a valuable candidate gene for developing crops with improved stress tolerance and high production potential. NAC (NAM/ATAF/CUC) is one of the largest transcription factor families. They play important roles in regulating plant development, aging, morphogenesis, as well as biotic and abiotic stress. There is a delicate balance between stress resistance and plant growth and development. To date, few genes have been identified in crops that can simultaneously enhance resistance and increase production. Sunflower, as a pioneering crop in saline-alkali soils, exhibit a certain level of tolerance to drought, barren, and saline-alkali stress. In this study, we identified a transcription factor gene, HaNAC146, which can improve both the growth and abiotic stress tolerance in transgenic Arabidopsis thaliana. Our main findings indicated that HaNAC146 is induced in sunflower by various abiotic stress and some plant hormones. It is localized in the nucleus and has transcriptional activation activity. HaNAC146 can promote growth, and increase seed production by enhancing photosynthesis in transgenic Arabidopsis. Utilizing a transient transformation system in sunflower and a stable transformation platform in Arabidopsis, we demonstrated that HaNAC146 can enhance the resistance of both sunflower seedlings and Arabidopsis to salt and drought stress. This enhancement is achieved through multiple pathways, including increasing antioxidant capacity, accumulating osmotic modulating substances, improving photosynthetic efficiency, activating the expression of downstream stress-responsive genes and promoting stomatal closure with plant sensitivity to abscisic acid (ABA). These results also indicated that robust growth is a key factor in plant resistance to abiotic stress. This unique stress-responsive transcription factor, HaNAC146, holds promise as a valuable candidate gene for developing crops with improved stress tolerance and high production potential.