Hormonal regulation of temperature-induced growth in Arabidopsis.
Successful plant survival depends upon the proper integration of information from the environment with endogenous cues to regulate growth and development. We have investigated the interplay between ambient temperature and hormone action during the regulation of hypocotyl elongation, and we have found that gibberellins (GAs) and auxin are quickly and independently recruited by temperature to modulate growth rate, whereas activity of brassinosteroids (BRs) seems to be required later on. Impairment of GA biosynthesis blocked the increased elongation caused at higher temperatures, but hypocotyls of pentuple DELLA knockout mutants still reduced their response to higher temperatures when BR synthesis or auxin polar transport were blocked. The expression of several key genes involved in the biosynthesis of GAs and auxin was regulated by temperature, which indirectly resulted in coherent variations in the levels of accumulation of nuclear GFP-RGA (repressor of GA1) and in the activity of the DR5 reporter. DNA microarray and genetic analyses allowed the identification of the transcription factor PIF4 (phytochrome-interacting factor 4) as a major target in the promotion of growth at higher temperature. These results suggest that temperature regulates hypocotyl growth by individually impinging on several elements of a pre-existing network of signaling pathways involving auxin, BRs, GAs, and PIF4.
Stavang
Jon A
JA
Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, N1432 As, Norway.
Gallego-Bartolomé
Javier
J
Gómez
María D
MD
Yoshida
Shigeo
S
Asami
Tadao
T
Olsen
Jorunn E
JE
García-Martínez
José L
JL
Alabadí
David
D
Blázquez
Miguel A
MA
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism*; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development; D007210:Indoleacetic Acids / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000378:metabolism*; D015398:Signal Transduction; D013256:Steroids / Q000378:metabolism; D013696:Temperature
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D018744:DNA, Plant; D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D013256:Steroids; C459466:PIF4 protein, Arabidopsis