SPATULA links daytime temperature and plant growth rate.
Plants exhibit a wide variety of growth rates that are known to be determined by genetic and environmental factors, and different plants grow optimally at different temperatures, indicating that this is a genetically determined character. Moderate decreases in ambient temperature inhibit vegetative growth, but the mechanism is poorly understood, although a decrease in gibberellin (GA) levels is known to be required. Here we demonstrate that the basic helix-loop-helix transcription factor SPATULA (SPT), previously known to be a regulator of low temperature-responsive germination, mediates the repression of growth by cool daytime temperatures but has little or no growth-regulating role under warmer conditions. We show that only daytime temperatures affect vegetative growth and that SPT couples morning temperature to growth rate. In seedlings, warm temperatures inhibit the accumulation of the SPT protein, and SPT autoregulates its own transcript abundance in conjunction with diurnal effects. Genetic data show that repression of growth by SPT is independent of GA signaling and phytochrome B, as previously shown for PIF4. Our data suggest that SPT integrates time of day and temperature signaling to control vegetative growth rate.
Sidaway-Lee
Kate
K
Department of Biology, University of York, P.O. Box 373, York YO10 5YW, UK.
Josse
Eve-Marie
EM
Brown
Alanna
A
Gan
Yinbo
Y
Halliday
Karen J
KJ
Graham
Ian A
IA
Penfield
Steven
S
D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000502:physiology*; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005875:Gibberellins / Q000494:pharmacology; D008027:Light; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000528:radiation effects; D013696:Temperature
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D005875:Gibberellins; D012333:RNA, Messenger; C426006:SPT protein, Arabidopsis; C007842:gibberellic acid