Unraveling the contribution of GASA gene family in sunflower under diverse stress conditions.

BACKGROUND

The gibberellic acid-stimulated Arabidopsis (GASA) gene family plays a critical role in plant growth, development, and responses to abiotic and biotic stresses. The GASA gene family has been extensively examined across several plant species; however, its functional role in Helianthus annuus (sunflower) remains inadequately characterized. There exists a lack of information regarding their expression profiles and regulatory mechanisms under stress conditions.

METHODS AND RESULTS

A genome-wide analysis was conducted to identify GASA genes in Sunflower, followed by phylogenetic classification, motif And gene structure Analysis, And synteny examination. Cis-regulatory elements were analyzed, and RNA-Seq data along with qRT-PCR were used to assess tissue-specific and drought-responsive expression patterns. We identified 27 HanGASA genes distributed across 11 chromosomes, which contain conserved domains. Phylogenetic and structural analyses revealed three main groups and distinct motif patterns. The modelled HanGASA proteins exhibited high structural similarity (70.53-100%), with GMQE (0.61-0.91) and QMEAND (0.60-0.87) scores confirming reliability. The validated 3D structures showed predominant random coil content (50-95.36%) and variable α-helix (3.25-48.36%) and β-turn (0-4.17%) proportions. Several genes exhibited tissue-specific expression, with HanGASA1, HanGASA10, HanGASA11, and HanGASA24 upregulated in roots, while HanGASA17 was upregulated in leaves under drought stress.

CONCLUSION

The findings elucidate the multifaceted roles of HanGASA genes in tissue-specific expression and response to drought stress. This study establishes a critical framework for subsequent functional analyses and the genetic enhancement of drought tolerance in sunflower.