The present invention concerns a method for increasing plant yield and/or increased stress resistance by decreasing the level of activity of a DEL1 polypeptide. One such method comprises introducing into a plant a nucleic acid comprising a variant DEL1 nucleic acid. Another method comprises downregulating expression of a DEL1 gene. The invention also relates to transgenic plants having introduced therein a variant DEL1 nucleic acid thereof, which plants have increased yield and/or increased stress resistance relative to control plants. The present invention also concerns a novel DEL1 protein and its encoding sequence, and constructs useful in the methods of the invention.