Convergence of signaling pathways in the control of differential cell growth in Arabidopsis.
Seedling apical hook development involves a complex interplay of hormones and light in the regulation of differential cell growth. However, the underlying molecular mechanisms that integrate these diverse signals to control bending of the embryonic stem are poorly understood. The Arabidopsis ethylene-regulated HOOKLESS1 (HLS1) gene is essential for apical hook formation. Herein, we identify two auxin response regulators that act downstream of HLS1 to control cell elongation in the hypocotyl. Extragenic suppressors of hls1 were identified as mutations in AUXIN RESPONSE FACTOR 2 (ARF2). The level of ARF2 protein was decreased by ethylene, and this response required HLS1. Exposure to light decreased HLS1 protein levels and evoked a concomitant increase in ARF2 accumulation. These studies demonstrate that both ethylene and light signals affect differential cell growth by acting through HLS1 to modulate the auxin response factors, pinpointing HLS1 as a key integrator of the signaling pathways that control hypocotyl bending.
Li
Hai
H
Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037 USA.
Johnson
Phoebe
P
Stepanova
Anna
A
Alonso
Jose M
JM
Ecker
Joseph R
JR
D020727:ADP-Ribosylation Factors / Q000235:genetics; D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D002455:Cell Division; D003001:Cloning, Molecular; D005030:Ethylenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D015151:Immunoblotting; D017403:In Situ Hybridization; D007210:Indoleacetic Acids / Q000378:metabolism; D008954:Models, Biological; D008957:Models, Genetic; D016296:Mutagenesis; D009154:Mutation; D010641:Phenotype; D010940:Plant Proteins / Q000502:physiology; D030821:Plants, Genetically Modified; D010957:Plasmids / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic
D005030:Ethylenes; C448325:HLS1 protein, Pisum sativum; D007210:Indoleacetic Acids; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; C036216:ethylene; C116686:ARF2 protein, S cerevisiae; D020727:ADP-Ribosylation Factors