Transcriptional profiling of ERF027 in Gossypium hirsutum L. under salt stress and calcium treatment

Salinity is one of the major abiotic stresses limiting cotton productivity worldwide, particularly in irrigated arid and semi-arid regions. Calcium ions (Ca²⁺) function as key secondary messengers in the salt stress signaling network, potentially modulating the expression of stress-responsive transcription factors. This study investigated the expression dynamics of the ethylene response factor ERF027 in upland cotton cultivar Garabagh-11 under sodium chloride (NaCl), calcium chloride (CaCl₂), and combined NaCl+CaCl₂ treatments. Using quantitative real-time PCR, we show that ERF027 is significantly upregulated in response to NaCl, suggesting its involvement in salt-induced transcriptional reprogramming. In contrast, CaCl₂ alone induced only a modest increase in ERF027 expression, while combined NaCl+CaCl₂ treatment reduced ERF027 expression by ~20% compared to NaCl alone, indicating that calcium may attenuate salt-triggered gene activation. These findings imply a buffering effect of Ca²⁺ signaling, possibly via improved ion homeostasis and modulation of ethylene-associated stress pathways. ERF027, a member of the AP2/ERF transcription factor family, appears to be a salt-inducible regulator that is sensitive to ionic interactions and calcium-mediated suppression. The study highlights a potential regulatory interface between salt and calcium signaling in cotton, offering insights into the transcriptional control of stress responses. These results lay the foundation for future efforts to manipulate calcium signaling pathways or ERF gene networks to enhance salt tolerance in cotton breeding programs. Keywords: Upland cotton, ethylene response factor, salinity, calcium signaling, gene expression