Benedict Catherine, Skinner Jeffrey S, Meng Rengong, Chang Yongjian, Bhalerao Rishikesh, Huner Norman P A, Finn Chad E, Chen Tony H H, Hurry Vaughan
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, S-901 87 Umeå, Sweden.
Plant Cell Environ. 2006 Jul;29(7):1259-72. doi: 10.1111/j.1365-3040.2006.01505.x.
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.
温带木本多年生植物的分生组织必须适应低温才能越冬，并在次年恢复生长。为了确定在一年生草本植物中参与这一过程的C-重复结合因子（CBF）转录因子家族在木本多年生植物中是否也发挥作用，我们研究了组成型表达拟南芥CBF1（AtCBF1）的转基因杨树的表型和转录谱变化。与野生型植株相比，AtCBF1的异位表达足以显著提高未驯化叶片和茎的抗冻性。cDNA微阵列实验鉴定了杨树中由AtCBF1异位表达上调的基因，证明了杨树和拟南芥之间CBF调控子的高度保守性，并鉴定了叶片和茎调控子之间的差异。我们研究了从毛果杨亚种毛果杨基因组序列（PtCBFs）中鉴定出的四个CBF旁系同源物的诱导动力学和组织特异性。所有四个PtCBFs在叶片中都是冷诱导的，但只有PtCBF1和PtCBF3在茎中表现出显著诱导。我们的结果表明，转录激活因子CBF家族在拟南芥冷驯化中所起的核心作用在杨树中得以保留。然而，PtCBFs的差异表达以及一年生（叶片）和多年生（茎）组织中CBF响应基因的不同簇表明，多年生植物驱动的冬季休眠进化可能导致这些“主开关”在木本植物不同的一年生和多年生组织中发挥特定作用。
