Detalle de: Abscisic acid signaling is controlled by a BRANCHED1/HD-ZIP I cascade in Arabidopsis axillary buds

Significance Shoot-branching patterns affect key aspects of plant life and are important targets for crop breeding. However, we are still ignorant of the genetic mechanisms controlling locally an important decision during branch development: whether the axillary bud grows out to give a lateral shoot or remains dormant. Here we show that the TEOSINTE BRANCHED1, CYCLOIDEA, PCF (TCP) transcriptional regulator BRANCHED1 (BRC1), which acts inside axillary buds, binds and activates three genes encoding Homeodomain leucine zipper (HD-ZIP) transcription factors. These factors, together with BRC1, trigger a cascade leading to local abscisic acid (ABA) accumulation and response, essential for bud dormancy under light-limiting conditions. This finding demonstrates a direct relationship between BRC1 and ABA signaling and places ABA downstream of BRC1 in the control of axillary bud dormancy.