The present invention is directed to transcription factor protein AP37 (APETELA 37) originating from rice which is related to tolerance of a plant to stress, a gene which encodes the protein, a recombinant vector comprising the gene, a host cell transformed with the recombinant vector, a method of producing a transgenic plant by using the recombinant vector, a method of improving tolerance of a plant to stress or increasing grain yield by transforming a plant cell with the recombination vector, a plant having improved tolerance to stress or increased grain yield produced according to said method, and a composition for improving tolerance of a plant to stress or for increasing grain yield under drought condition comprising the gene encoding AP37 protein as an effective component.
