Xylem-specific gene expression in loblolly pine.
Two genes preferentially expressed in differentiating xylem of loblolly pine (Pinus taeda L.) were cloned from cDNA and genomic libraries and designated PtX3H6 and PtX14A9. Transcripts of PtX3H6 and PtX14A9 are very abundant in differentiating xylem, less abundant in needles, and very low or non-detectable in embryos and megagametophytes. PtX3H6 contains a putative signal peptide, a threonine-rich region, a proline-rich region, and a hydrophobic tail. Repeats of Pro-Pro-Pro-Val-X-X are similar to repeats found in proline-rich cell wall proteins. The amino acid compositions of PtX3H6 and PtX14A9 are similar to those of arabinogalactan proteins (AGPs). PtX14A9 contains an 8 amino acid sequence similar to amino terminal sequences of ryegrass, carrot and rose AGPs. Upstream sequences have been determined from genomic clones encoding PtX3H6 and PtX14A9. A 7 bp sequence found in the 5' flanking regions of both genes has previously been shown to be involved in the vascular-specific expression of GRP 1.8, a glycine-rich protein found in bean. The sequence is also present upstream of another glycine-rich protein from bean, GRP 1.0, and may be partially responsible for the xylem-specific expression of pTx3H6 and PtX14A9.
Loopstra
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Department of Forestry, North Carolina State University, Raleigh 27695-8008.
Sederoff
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D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001483:Base Sequence; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics; D015698:Genomic Library; D008969:Molecular Sequence Data; D041603:Pinus taeda; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D018547:Plant Stems / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D021382:Protein Sorting Signals / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D018749:RNA, Plant / Q000032:analysis; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000235:genetics
D000596:Amino Acids; D010940:Plant Proteins; D021382:Protein Sorting Signals; C092519:PtX14A9 protein, Pinus taeda; C092518:PtX3H6 protein, Pinus taeda; D012333:RNA, Messenger; D018749:RNA, Plant