Hybrid proline-rich proteins and cell elongation

The growth of plant cells is generally related to loosening of the cell wall, which allows cell expansion driven by osmotic water uptake. Dvorakova et al. demonstrate a correlation between over-expression of genes encoding members of the family of hybrid proline-rich proteins (HyPRPs) and enhanced elongation of tobacco BY-2 cells. The results suggest that HyPRPs, more specifically their C-terminal domains related to lipid transfer proteins, represent a novel group of proteins involved in cell-wall loosening.