title: Transcriptome profiling of vertical stem segments provides insights into the genetic regulation of secondary growth in hybrid aspen trees.
abstract: In order to better understand the genetic regulation of secondary growth in hybrid aspen (Populus tremula L.xP. alba L.), we carried out a series of cDNA-amplified fragment length polymorphism (AFLP)-based transcriptome analyses in vertical stem segments that represent a gradient of developmental stages with regard to secondary growth. This approach allowed us to screen >80% of the transcriptome expressed in six samples and identify genes differentially expressed with the progress of secondary growth, in a tissue-specific manner. Of the 76,800 transcript-derived fragments (TDFs) analyzed, 271 TDFs were selected and sequenced based on their differential expression patterns. Many of the xylem-up-regulated genes were involved in cell wall and lignin biosynthesis, while the bark-up-regulated genes had diverse functional roles. About 25% of the xylem-up-regulated TDFs analyzed were involved in the phenylpropanoid biosynthesis pathway, which produces the cell wall polymer lignin and various wood extractives. In addition, many of the TDFs showing secondary xylem-specific expression were annotated as genes not previously reported in Populus, including novel cell death proteins, cytoskeleton-interacting proteins, transporters and putative transcription factors.
authors.affiliation: Department of Forestry, Michigan State University, 126 Natural Resources, East Lansing, MI 48824-1222, USA.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Prassinos
authors.forename: Jae-Heung
authors.initials: JH
authors.lastname: Ko
authors.forename: Jaemo
authors.initials: J
authors.lastname: Yang
authors.forename: Kyung-Hwan
authors.initials: KH
authors.lastname: Han
mesh_terms: D015152:Blotting, Northern; D018076:DNA, Complementary; D020869:Gene Expression Profiling; D017343:Genes, Plant; D008969:Molecular Sequence Data; D032107:Populus / Q000235:genetics / Q000254:growth & development*; D012333:RNA, Messenger / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger