Arsenic-induced galactinol synthase1 gene, AtGolS1, provides arsenic stress tolerance in Arabidopsis thaliana

Combating stress conditions and maintaining cellular homeostasis are integral to plant growth and development. To maintain cellular integrity, defence mechanisms against abiotic stresses often work by accumulating molecules, including antioxidants, secondary metabolites, and soluble sugars. The Raffinose Family of Oligosaccharide (RFO) biosynthesis is an extension of sucrose metabolism involving galactinol synthase (GolS). GolS transfers galactosyl moieties to myo-inositol to generate Galactinol, followed by the formation of Raffinose and Stachyose. GolS, being the rate-limiting enzyme, is often targeted to understand this pathway's role under different stress conditions; however, till now, the involvement of GolS1 in heavy metal stress remains unknown. This study demonstrates an increase in AtGolS1 expression and Galactinol accumulation in response to arsenic (As) stress in Arabidopsis thaliana. Analysis of transgenic lines over-expressing AtGolS1 revealed an improved growth under As stress. Contrasting sensitivity by Arabidopsis mutant under As further validated the role of AtGolS1 in combating As stress. Response of transgenic lines expressing a reporter gene, GUS, under the AtGolS1 promoter suggests responsiveness of GolS1 to As stress. This study implies that AtGolS1 is inducible by As stress at the transcriptional and metabolic levels, possibly to mitigate excessive ROS production and provide tolerance under As stress in plants.