Microarray gene expression profiling of developmental transitions in Sitka spruce (Picea sitchensis) apical shoots

J Exp Bot. 2007;58(3):593-614. doi: 10.1093/jxb/erl246. Epub 2007 Jan 13.


The apical shoot drives the yearly new stem growth of conifer trees, is the primary site for the establishment of chemical and physical defences, and is important in establishing subsequent perennial growth. This organ presents an interesting developmental system, with growth and development progressing from a meristematic tip through development of a primary vascular system, to a base with fully differentiated and lignified secondary xylem on the inside and bark tissue with constitutive defence structures such as resin, polyphenolic phloem parenchyma cells, and sclereids on the outside. A spruce (Picea spp.) microarray containing approximately 16.7K unique cDNAs was used to study transcript profiles that characterize the developmental transition in apical shoots of Sitka spruce (Picea sitchensis) from their vegetative tips to their woody bases. Along with genes involved in cell-wall modification and lignin biosynthesis, a number of differentially regulated genes encoding protein kinases and transcription factors with base-preferred expression patterns were identified, which could play roles in the formation of woody tissues inside the apical shoot, as well as in regulating other developmental transitions associated with organ maturation. Preferential expression of known conifer defence genes, genes encoding defence-related proteins, and genes encoding regulatory proteins was observed at the apical shoot tip and in the green bark tissues at the apical shoot base, suggesting a commitment to constitutive defence in the apical shoot that is co-ordinated with rapid development of secondary xylem.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Plant / classification
  • Antigens, Plant / genetics
  • Antigens, Plant / metabolism
  • Carbohydrate Metabolism
  • Carrier Proteins / classification
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cell Wall / metabolism
  • Gene Expression Profiling
  • Lignin / biosynthesis
  • Likelihood Functions
  • Oligonucleotide Array Sequence Analysis
  • Phylogeny
  • Picea / anatomy & histology
  • Picea / genetics*
  • Picea / growth & development*
  • Plant Proteins / classification
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plant Shoots / anatomy & histology
  • Plant Shoots / genetics
  • Plant Shoots / growth & development
  • Plant Stems / anatomy & histology
  • Plant Stems / genetics
  • Plant Stems / growth & development
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Xylem / anatomy & histology
  • Xylem / genetics
  • Xylem / growth & development


  • Antigens, Plant
  • Carrier Proteins
  • Plant Proteins
  • Transcription Factors
  • lipid transfer proteins, plant
  • Lignin