Systemic low temperature signaling in Arabidopsis.
When leaves are exposed to low temperature, sugars accumulate and transcription factors in the C-repeat binding factor (CBF) family are expressed, which, together with CBF-independent pathways, are known to contribute to the cold acclimation process and an increase in freezing tolerance. What is not known, however, is whether expression of these cold-regulated genes can be induced systemically in response to a localized cold treatment. To address this, pre-existing, mature leaves of warm-grown Arabidopsis thaliana were exposed to a localized cold treatment (near 10 °C) whilst conjoined newly developing leaves continued only to experience warmer temperatures. In initial experiments on wild-type A. thaliana (Col-0) using real-time reverse transcription--PCR (RT-PCR) we observed that some genes--including CBF genes, certain downstream cold-responsive (COR) targets and CBF-independent transcription factors--respond to a direct 9 °C treatment of whole plants. In subsequent experiments, we found that the treatment of expanded leaves with temperatures near 10 °C can induce cold-associated genes in conjoined warm-maintained tissues. CBF1 showed a particularly strong systemic response, although CBF-independent transcription factors also responded. Moreover, the localized cold treatment of A. thaliana (C24) plants with a luciferase reporter fused to the promoter region of KIN2 indicated that in warm-maintained leaves, KIN2 might respond to a systemic signal from remote, directly cold-treated leaves. Collectively, our study provides strong evidence that the processes involved in cold acclimation are partially mediated by a signal that acts systemically. This has the potential to act as an early-warning system to enable developing leaves to cope better with the cold environment in which they are growing.
Gorsuch
Peter A
PA
Department of Biology, University of York, PO Box 373, York YO105YW, UK.
Sargeant
Alexander W
AW
Penfield
Steven D
SD
Quick
W Paul
WP
Atkin
Owen K
OK
D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D018506:Gene Expression Regulation, Plant; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; C104387:CBF1 protein, Arabidopsis; D015534:Trans-Activators; C075575:KIN 2 protein, Arabidopsis