The CBF1-dependent low temperature signalling pathway, regulon and increase in freeze tolerance are conserved in Populus spp.
The meristematic tissues of temperate woody perennials must acclimate to freezing temperatures to survive the winter and resume growth the following year. To determine whether the C-repeat binding factor (CBF) family of transcription factors contributing to this process in annual herbaceous species also functions in woody perennials, we investigated the changes in phenotype and transcript profile of transgenic Populus constitutively expressing CBF1 from Arabidopsis (AtCBF1). Ectopic expression of AtCBF1 was sufficient to significantly increase the freezing tolerance of non-acclimated leaves and stems relative to wild-type plants. cDNA microarray experiments identified genes up-regulated by ectopic AtCBF1 expression in Populus, demonstrated a strong conservation of the CBF regulon between Populus and Arabidopsis and identified differences between leaf and stem regulons. We studied the induction kinetics and tissue specificity of four CBF paralogues identified from the Populus balsamifera subsp. trichocarpa genome sequence (PtCBFs). All four PtCBFs are cold-inducible in leaves, but only PtCBF1 and PtCBF3 show significant induction in stems. Our results suggest that the central role played by the CBF family of transcriptional activators in cold acclimation of Arabidopsis has been maintained in Populus. However, the differential expression of the PtCBFs and differing clusters of CBF-responsive genes in annual (leaf) and perennial (stem) tissues suggest that the perennial-driven evolution of winter dormancy may have given rise to specific roles for these 'master-switches' in the different annual and perennial tissues of woody species.
Benedict
Catherine
C
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, S-901 87 Umeå, Sweden.
Skinner
Jeffrey S
JS
Meng
Rengong
R
Chang
Yongjian
Y
Bhalerao
Rishikesh
R
Huner
Norman P A
NP
Finn
Chad E
CE
Chen
Tony H H
TH
Hurry
Vaughan
V
D000040:Abscisic Acid / Q000378:metabolism; D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016000:Cluster Analysis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004190:Disasters; D005615:Freezing; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D018745:Genome, Plant / Q000235:genetics; D046228:Microarray Analysis; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000502:physiology; D018547:Plant Stems / Q000502:physiology; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D018085:Regulon / Q000235:genetics*; D020218:Response Elements / Q000235:genetics; D015398:Signal Transduction; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000235:genetics
D029681:Arabidopsis Proteins; C104387:CBF1 protein, Arabidopsis; D004268:DNA-Binding Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000040:Abscisic Acid