1. The Jacob Blaustein Desert Research Institute, Ben-Gurion University of the Negev, Sede Boqer 84993, The Institutes for Applied Research, Ben-Gurion University of the Negev, Beer Sheva 84110, 2 Israel, and Equipe Polysaccharides Parietaux des Vegetaux, University of Lille, 59655 Villeneuve d'Ascq, France3