A triple-HLH/bHLH Cascade Controls Cell Elongation Downstream of Multiple Hormonal and Environmental Signaling Pathways

ABSTRACT: The environmental and endogenous signals, light, temperature, brassinosteroid (BR), and gibberellin (GA), regulate cell elongation largely by controlling the expression of the PRE family helix-Loop-helix (HLH) factors, which promote cell elongation by interacting antagonistically with another HLH factor, IBH1. But the molecular mechanism by which PREs and IBH1 regulate gene expression has remained unknown. Here we show that IBH1 interacts with and inhibits a DNA-binding bHLH protein HBI1. Overexpression of HBI1 increased hypocotyl and petiole elongation, whereas dominant inactivation of HBI1 and its homologs caused a dwarf phenotype, indicating that HBI1 is a positive regulator of cell elongation. In vitro and in vivo experiments showed that HBI1 directly bound to the promoters and activat

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Mingyi Bai 

PROVIDER: E-GEOD-41766 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress