CHARACTERIZATION OF THE EXTRACELLULAR-MATRIX PRODUCED INVITRO BY UREDINIOSPORES AND SPORELINGS OF UROMYCES-VICIAE-FABAE

The composition and pattern of temporal release of extracellular matri x produced in vitro by urediniospores and sporelings of Uromyces vicia e-fabae is presented. In shake culture, proteins, neutral sugars and u ronic acids are released in a diphasic manner which correlates with st ages of the germination process and decrease in culture pH. During the initial phase, prior to germ tube emergence, predominantly low-molecu lar-weight carbohydrates are liberated with some high-molecular-weight polypeptides. These probably originate from solubilization of the spo re surface matrix and lysis of the germ pore plug. The second phase of release, concurrent with germ-tube emergence and elongation, is chara cterized by increasing concentrations of high-molecular-weight polypep tides, some of which may be glycosylated. Phosphatase, glycosidase, es terase and proteolytic activity is present in the matrix prior to germ ination and during both subsequent phases. The pattern of polymer rele ase and the pH changes recorded may reflect differing mechanisms of sy nthesis and liberation which may be important both for the adhesion of sporelings to substrata and for the localization and activity of extr acellular enzymes.