Abstract
Stems of higher plants offer support to the aerial portion of the plant body and serve as conduits for the translocation of nutrients and water. Using gene-specific oligonucleotide microarray system, we identified a set of genes that play important roles in specific aspects of cell wall construction in basal of the inflorescence stem of Arabidopsis. Some of the genes are involved in secondary wall deposition of xylem cells during vascular development. The expression of these genes sharply decreased when the inflorescence stem are placed horizontally. The results suggest that the weight carried by the upper part of the stem may be a signal for the induction of cell wall rigidification in basal of the stem. Reverse genetics analysis for function of the genes indicated that glycine-rich protein modifies mechanical strength of the cell wall in protoxylem in basal of the stem, thereby providing a conduit for the translocation of water.
