A novel method of imparting stress tolerance, particularly light stress tolerance and oxidation stress tolerance, to a plant is provided. A transporter that transports an ascorbate to a chloroplast was identified and role of the transporter in imparting tolerance to a plant was clarified. The present invention utilizes an ascorbate transporter and a gene encoding the ascorbate transporter, thereby providing a composition and a method that impart stress tolerance, particularly light stress tolerance and oxidation stress tolerance, to a plant.