Fuente: WIPO "tomato" Provided is a method for generating a plant having improved growth and/or yield. The method comprises selectively increasing the size of one or more guard cells in a plant wherein the guard cell size is increased compared to guard cell size in an independent wild type control plant of the same species under the same environmental conditions. The ratio of guard cell size to leaf epidermal cell size in the plant is increased as compared to the ratio in the control plant. Also provided is a plant obtainable by the method; a gene construct; a transformed plant part or plant progeny; and a plant part, plant tissue, plant organ, plant cell, plant protoplast, embryo, callus culture, pollen grain or seed, derived or obtained from the plant.