Role of phi cells and the endodermis under salt stress in Brassica oleracea
Article first published online: 5 NOV 2008
© The Authors (2008). Journal compilation © New Phytologist (2008)
Volume 181, Issue 2, pages 347–360, January 2009
How to Cite
Fernandez-Garcia, N., Lopez-Perez, L., Hernandez, M. and Olmos, E. (2009), Role of phi cells and the endodermis under salt stress in Brassica oleracea. New Phytologist, 181: 347–360. doi: 10.1111/j.1469-8137.2008.02674.x
- Issue published online: 16 DEC 2008
- Article first published online: 5 NOV 2008
- Received: 4 July 2008; Accepted: 14 September 2008
- broccoli (Brassica oleracea);
- phi thickenings;
- salt stress
- • Phi cell layers were discovered in the 19th century in a small number of species, including members of the Brassicaceae family. A mechanical role was first suggested for this structure; however, this has never been demonstrated. The main objective of the present work was to analyse the ultrastructure of phi cells, their influence on ion movement from the cortex to the stele, and their contribution to salt stress tolerance in Brassica oleracea.
- • Transmission electron microscopy and X-ray microanalysis studies were used to analyse the subcellular structure and distribution of ions in phi cells and the endodermis under salt stress. Ion movement was analysed using lanthanum as an apoplastic tracer.
- • The ultrastructural results confirm that phi cells are specialized cells showing cell wall ingrowths in the inner tangential cell walls. X-ray microanalysis confirmed a build-up of sodium. Phi thickenings were lignified and lanthanum moved periplasmically at this level.
- • To the best of our knowledge, this is the first study reporting the possible role of the phi cells as a barrier controlling the movement of ions from the cortex to the stele. Therefore, the phi cell layer and endodermis seem to be regulating ion transport in Brassica oleracea under salt stress.