Table I.

Genes with known preferential expression in epidermis or in vascular tissues were correctly identified by the microarray experiments using epidermal peels from stems

List of genes whose preferential or specific site of expression is epidermis (top of the list) or vascular tissues (bottom) as shown by techniques other than microarrays. The organ investigated and the reference is given. For known housekeeping genes (middle), only a few randomly selected examples are given. Molecular function of the proteins encoded by the genes: ACR4, putative receptor kinase; ATML1 and PDF2, homeodomain protein; AtPIN1, putative auxin efflux carrier protein; AtPPT1 (=cue1), phosphoenolpyruvate/phosphate translocator; CER2, unknown protein; CER5, ABC transporter; CBP20 and CBP80, nuclear cap binding protein; CER6 (=CUT1) and FDH (FIDDLEHEAD), β-ketoacyl-CoA synthase; LACERATA, fatty acid ω-hydroxylase; LACS2, long-chain acyl-CoA synthetase; L23a, 60S ribosomal protein; PPX1 and PPX2, protein phosphatase; UBQ1, ubiquitin extension protein; XCP1 and XCP2, cysteine peptidase; WAX2 (=YORE-YORE), unknown.

Gene LocusGene NameExpression RatioaPreferential ExpressionReference
TopBase
Epidermal
At3g59420ACR424.819.1    Epidermis (all organs)Tanaka et al. (2002)
At4g21750ATML16.25.5    L1 layer of shoot apexSessions et al. (1999)
At4g04890PDF26.05.9    L1 layer of shoot apexAbe et al. (2003)
At4g24510CER24.16.0    EpidermisXia et al. (1997)
At2g26250FDH4.03.9    EpidermisYephremov et al. (1999); Pruitt et al. (2000)
At1g51500CER53.53.1    Epidermis (stem)Pighin et al. (2004)
At1g68530CER63.13.1    Shoot epidermisMillar et al. (1999)
At2g45970LACERATA3.12.2    Epidermis-specificWellesen et al. (2001)
At5g57800WAX22.62.2    L1 layer of shoot apexChen et al. (2003); Kurata et al. (2003)
At1g49430LACS22.51.2    Epidermis (leaf)Schnurr et al. (2004)
Ubiquitous
At5g55260PPX21.61.6    All tissuesPujol et al. (2000)
At3g52590UBQ11.11.6    Most tissuesHoltorf et al. (1995)
At4g26720PPX11.01.2    All tissuesPujol et al. (2000)
At3g18780Actin 20.90.7    Vegetative tissuesAn et al. (1996)
At2g13540CBP800.80.8    Most tissuesKmieciak et al. (2002)
At5g44200CBP200.71.0    Most tissuesKmieciak et al. (2002)
At1g49240Actin 80.60.7    Vegetative tissuesAn et al. (1996)
At3g55280L23a0.61.4    Most tissuesVolkov et al. (2003)
Vascular
At5g33320AtPPT10.41.0    Stem vasculatureKnappe et al. (2003)
At1g73590AtPIN10.20.2    Xylem and cambiumGälweiler et al. (1998)
At4g35350XCP10.10.5    XylemFunk et al. (2002)
At1g20850XCP20.10.3    XylemZhao et al. (2000)
  • a Mean ratio calculated from four epidermis-to-stem gene expression ratios, i.e. ratio of transcripts in epidermis versus transcripts in stems, determined by microarray experiments (Affymetrix ATH1 GeneChip) using the epidermis of a stem section (top or base) and the whole-stem section (top or base) as a reference.