SbHsp70 overexpression enhances drought and salinity tolerance in wheat through improved cellular stability and stress-associated structural adaptations

Introduction: Drought and salinity are major constraints to wheat productivity worldwide. Heat shock protein 70 (Hsp70) is a conserved molecular chaperone implicated in plant stress responses, but its role in cellular stability and structural adaptation in wheat remains poorly understood.

Methods: To investigate its function, the sorghum-derived SbHsp70 gene was constitutively overexpressed in durum wheat (cv. Kofa) and bread wheat (cv. Bobwhite) via particle bombardment. Transgenic lines were evaluated under controlled drought and salinity stress conditions using physiological, cellular, molecular, and agronomic analyses.

Results: SbHsp70 overexpression enhanced drought and salinity tolerance in both wheat backgrounds. Transgenic plants maintained higher membrane stability, relative water content, and photosynthetic activity under stress. Enhanced interlocking marginal lobe formation, altered actin organization, and modulation of stress-responsive gene expression were also observed. Importantly, transgenic lines maintained agronomic performance under drought without yield penalties under well-watered conditions.

Discussion: These findings suggest that SbHsp70 contributes to abiotic stress tolerance through improved cellular stability and stress-associated structural adaptations. While the observed cytoskeletal and transcriptional changes indicate a coordinated stress response, further studies are required to elucidate the underlying molecular mechanisms.