Proline as a biochemical marker in relation to the ecology of two halophytic Juncus species

Osmolytes, used for maintaining osmotic balance and as ‘osmoprotectans’, are synthesised in plants as a general, conserved response to abiotic stress, although their contribution to stress tolerance mechanisms is still unclear. Proline, the most common osmolyte, accumulates in many plant species in parallel with an increase in external salinity, and is considered as a reliable biochemical marker of salt stress. We have measured proline levels in two halophytic, closely related Juncus species, under laboratory and field conditions, to assess the possible relevance of proline biosynthesis for salt tolerance and therefore for the ecology of these two taxa.
This work has been supported by grants from the Spanish Ministry of Science and Innovation – with contribution from the European Regional Development Fund – to O. Vicente (project CGL2008-00438/BOS), and from the Polytechnic University of Valencia to M. Boscaiu (programme PAID-06-09).