Functional characterization of promoter conferring hormone- and stress-induced expression: a potential tool to improve growth and stress tolerance in cotton.

Unlabelled: The GhNAC2 transcription factor identified from improves root growth and drought tolerance through transcriptional reprogramming of phytohormone signaling. The promoter of such a versatile gene could serve as an important genetic engineering tool for biotechnological application. In this study, we identified and characterized the promoter of to understand its regulatory mechanism. transcription factor increased in root tissues in response to GA, ethylene, auxin, ABA, mannitol, and NaCl. In silico analysis revealed an overrepresentation of -regulatory elements associated with hormone signaling, stress responses and root-, pollen-, and seed-specific promoter activity. To validate their role in function/regulation, an 870-bp upstream regulatory sequence was fused with the GUS reporter gene () and expressed in and cotton hairy roots for characterization. Histochemical GUS staining indicated localized expression in root tips, root elongation zone, root primordia, and reproductive tissues under optimal growth conditions. Mannitol, NaCl, auxin, GA, and ABA, induced the promoter-driven GUS expression in all tissues while ethylene suppressed the promoter activity. The results show that the 870 nt fragment of the promoter drives root-preferential expression and responds to phytohormonal and stress signals. In corroboration with promoter regulation, GA and ethylene pathways differentially regulated root growth in -expressing . The findings suggest that differential promoter activity governs the expression of in root growth and stress-related functions independently through specific promoter elements. This multifarious promoter can be utilized to develop yield and climate resilience in cotton by expanding the options to control gene regulation.

Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01411-2.