Suppression of SlDREB3 increases leaf ABA responses and promotes drought tolerance in transgenic tomato plants.

Drought susceptibility is a major yield limiting factor in agricultural crops especially in hybrids/varieties that have been bred for high yields. We show that manipulation of the SlDREB3 gene in tomato alters ABA responses and thereby sensitivity of stomatal closure to ABA. SlDREB3 suppression lines show ABA hypersensitivity and rapid stomatal closure in response to ABA while over-expression lines show reduced sensitivity to ABA and open stomata even at high ABA levels with rapid water loss after 10 days of water stress.

SlDREB3, a negative regulator of ABA responses, controls seed germination, fruit size and the onset of ripening in tomato.

SlDREB3 was identified as a ripening up-regulated gene of the AP2/ERF-domain family of transcription factors. Its manipulation affects processes primarily governed by ABA. It negatively regulates ABA responses in tomato by altering ABA levels/signaling and is, in turn, negatively regulated by ABA.