THE APOPLAST - ITS SIGNIFICANCE FOR THE NUTRITION OF HIGHER-PLANTS

Since the fundamental work of the botanist Ernst Munch there has been a clear differentiation between a symplastic and an apoplastic compart ment of plants, separated by the plasmalemma. In contrast to the sympl ast, the apoplast was considered as being dead and hence attracted lit tle interest. It is not before the late seventies of this century that plant scientists realised that processes such as growth and different iation as well as signal transduction may not be understood without ac counting for apoplastic processes. Since then growing evidence has sup ported the view that apoplastic properties are of significance for suc h diverse processes as genotypic variation in nutrient efficiency and tolerance against adverse ion relations, for plant/microbe interaction , or for water and nutrient transport. In this contribution we review apoplastic properties and processes in relation to plant mineral nutri tion. Examples are taken from work being conducted in the scope of the special research project of the German Research Foundation ''The apop last of higher plants: compartment for storage, transport and reaction s'' and especially from own work.