A genomic approach to suberin biosynthesis and cork differentiation.
Cork (phellem) is a multilayered dead tissue protecting plant mature stems and roots and plant healing tissues from water loss and injuries. Cork cells are made impervious by the deposition of suberin onto cell walls. Although suberin deposition and cork formation are essential for survival of land plants, molecular studies have rarely been conducted on this tissue. Here, we address this question by combining suppression subtractive hybridization together with cDNA microarrays, using as a model the external bark of the cork tree (Quercus suber), from which bottle cork is obtained. A suppression subtractive hybridization library from cork tree bark was prepared containing 236 independent sequences; 69% showed significant homology to database sequences and they corresponded to 135 unique genes. Out of these genes, 43.5% were classified as the main pathways needed for cork biosynthesis. Furthermore, 19% could be related to regulatory functions. To identify genes more specifically required for suberin biosynthesis, cork expressed sequence tags were printed on a microarray and subsequently used to compare cork (phellem) to a non-suberin-producing tissue such as wood (xylem). Based on the results, a list of candidate genes relevant for cork was obtained. This list includes genes for the synthesis, transport, and polymerization of suberin monomers such as components of the fatty acid elongase complexes, ATP-binding cassette transporters, and acyltransferases, among others. Moreover, a number of regulatory genes induced in cork have been identified, including MYB, No-Apical-Meristem, and WRKY transcription factors with putative functions in meristem identity and cork differentiation.
Soler
Marçal
M
Laboratori del suro, Department of Biology, Facultat de Ciències, Universitat de Girona, Campus Montilivi s/n, 17071 Girona, Spain.
Serra
Olga
O
Molinas
Marisa
M
Huguet
Gemma
G
Fluch
Silvia
S
Figueras
Mercè
M
D001692:Biological Transport / Q000235:genetics; D002454:Cell Differentiation; D002473:Cell Wall / Q000378:metabolism; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D023281:Genomics / Q000379:methods*; D008055:Lipids / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D029963:Quercus / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014934:Wood / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism
D008055:Lipids; D010940:Plant Proteins; C065875:suberin