The ARF2-ANT-COR15A gene cascade regulates ABA-signalingmediated resistance of large seeds to drought in Arabidopsis

Abstract

Seedlings of large-seeded plants are considered to be able towithstand abiotic stresses efficiently. Themolecularmechanisms that underlie the involved signaling crosstalk between the large-seeded trait and abiotic tolerance are, however, largely unknown. Here, we demonstrate the molecular link that integrates plant abscisic acid (ABA) responses to drought stress into the regulation of seed mass. Both loss-of-function mutants of the Auxin Response Factor 2 (ARF2 encoding a transcription factor) and lines overexpressing AINTEGUMENTA (ANT; a transcription factor) under the 35S promoter exhibited large seed and drought-tolerant phenotypes as a result of abnormal ABA- auxin crosstalk signaling pathways in Arabidopsis. The target gene COLD-REGULATED15A (COR15a) was identified as participating in the regulation of seed development with ABA signaling through a negative regulationmechanismthat ismediated byANT. Themolecular and genetic evidence presented indicate that ARF2, ANT andCOR15A form an ABA-mediated signaling pathway to link modulation of seed mass with drought tolerance. These observations indicate that the ARF2 transcription factor serves as amolecular link that integrates plant ABA responses to drought stress into the regulation of seed mass.