Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida
Article first published online: 27 APR 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 191, Issue 3, pages 662–677, August 2011
How to Cite
Zenoni, S., Fasoli, M., Tornielli, G. B., Dal Santo, S., Sanson, A., de Groot, P., Sordo, S., Citterio, S., Monti, F. and Pezzotti, M. (2011), Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida. New Phytologist, 191: 662–677. doi: 10.1111/j.1469-8137.2011.03726.x
- Issue published online: 20 JUL 2011
- Article first published online: 27 APR 2011
- Received: 18 January 2011, Accepted: 11 March 2011
- axillary meristem;
- cell expansion;
- cell wall;
- Petunia hybrida
- •Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants.
- •PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein’s subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers.
- •The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed.
- •These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism.