Daniel Cosgrove, a professor of biology at Pennsylvania State University, University Park, says that this paper breaks new ground in that it gives the first insights into "the biochemical basis of one of the key processes in plant-cell growth; namely, the extension of the cell walls.
"We identified proteins that make cell walls grow in surface area," he adds.
Plant-cell walls are composed of large units of polysaccharides (such as cellulose fibers), held together by hydrogen bonds, with different proteins embedded in this matrix.
The newly discovered proteins, explains Cosgrove, "act on the polysaccharide component of the cell wall to cause slippage between units so as to enable extension. "For more than 50 years, people had hypothesized the presence of such 'wall loosening'...