Developmental and seasonal expression of PtaHB1, a Populus gene encoding a class III HD-Zip protein, is closely associated with secondary growth and inversely correlated with the level of microRNA (miR166)

New Phytol. 2006;169(3):469-78. doi: 10.1111/j.1469-8137.2005.01623.x.


In contrast to our knowledge of the shoot apical meristem, our understanding of cambium meristem differentiation and maintenance is limited. Class III homeodomain leucine-zipper (HD-Zip) proteins have been shown to play a regulatory role in vascular differentiation. The hybrid aspen (Populus tremulaxPopulus alba) class III HD-Zip transcription factor (PtaHB1) and microRNA 166 (Pta-miR166) family were cloned from hybrid aspen using a combination of in silico and polymerase chain reaction methods. Expression analyses of PtaHB1 and Pta-miR166 were performed by Northern blot analysis. The expression of PtaHB1 was closely associated with wood formation and regulated both developmentally and seasonally, with the highest expression during the active growing season. Also, its expression was inversely correlated with the level of Pta-miR166. Pta-miR166-directed cleavage of PtaHB1 in vivo was confirmed using modified 5'-rapid amplification of cDNA ends (RACE). The expression of Pta-miR166 was much higher in the winter than in the growing seasons, suggesting seasonal and developmental regulation of microRNA in this perennial plant species.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Cloning, Molecular
  • Conserved Sequence
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Plant*
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • MicroRNAs / chemistry
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Molecular Sequence Data
  • Phylogeny
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plant Stems / anatomy & histology
  • Plant Stems / growth & development
  • Plant Stems / metabolism
  • Populus / genetics*
  • Populus / growth & development*
  • Populus / metabolism
  • RNA, Messenger / metabolism
  • Seasons*
  • Sequence Alignment
  • Structural Homology, Protein


  • Arabidopsis Proteins
  • Homeodomain Proteins
  • IFL1 protein, Arabidopsis
  • MicroRNAs
  • Plant Proteins
  • RNA, Messenger