NEW DESCRIPTORS TO EVALUATE THE CONSERVATION STATUS OF POSIDONIA OCEANICA MEADOW Proceedings of the 4th Mediterranean Symposium on Marine Vegetation (Yasmine-Hammamet, 2-4 December 2010)

Human activities and natural events are responsible for a widespread regression of the Posidonia oceanica (Magnoliophyta, Liliopsida) meadows. Early warning indicators are necessary to implement coastal management procedures to quikly guide managers in determining recovery actions. We recently proposed an innovative "diagnostic" tool to monitor the plant conservation status: the quantification of the phenols content, as a putative stress indicator, coupled to the 2-D electrophoresis analysis of proteins from rhizomes. The increased concentration of total phenols in Posidonia rhizome represents a generic response to different kinds of environmental stress and phenols determination is an easy and rapid assay for the screening of the meadows health state. The pattern of protein expression, the proteome, is the entire set of proteins expressed in a given moment. It is a dynamic entity varying in response to endogenous or exogenous stimuli, such as changing environmental conditions. In this work, by analysing 2005-2010 samples from S. Marinella (Roma, Italy) meadow, we demonstrate that the decreasing plant density has been physiologically marked by the increase of total phenols content. Peculiar 2D-electrophoresis protein maps are associated to the different phenols content, i.e. protein spots were differentially expressed at high or low phenols content. These data superimpose to an increased anthropic pressure in the area where a new harbor is under construction not so far (Civitavecchia, since 2005) and agricultural practices are continuously intensifying. Hence, the combined approach, based on phenols content determination and 2-D electrophoresis protein pattern analysis, is confirmed as a promising tool to monitor the health state of Posidonia meadows.