1.4-β-Galactanases and 1.3-β-Glucanases of Botrytis cinerea Isolate Infecting Apple

Abstract

It was shown that Botrytis cinerea , an isolate infecting apple secreted 1,4-β-galactanase and 1,3-β-glucanase in culture on apple homogenate as well as during growth on intact apples. Isoelectric focusing (IEF) of enzymes from the culture on apple homogenate showed the presence of two forms of 1,4-β-galactanase with isoelectric points (pI) of 7,3 (Gal I) and 6,2 (Gal II) and two forms of 1,3-β-glucanase with pl of 5,7 (Glu I) and 4,1 (Glu II). After IEF of enzymes from infected apple two 1,4-β-galactanases with pI identical with those from apple homogenate and one of 1,3-β-glucanase with pI identical with that of Glu II from homogenate were obtained. Gal I, Gal II and Glu II attacked their substrate in endo-manner, Glu I in exo-manner. Both galactanases and glucanases were capable of apple cell wall hydrolysis, though the latter hydrolyzed walls poorly. Glycoprotein fraction from apple was hydrolyzed by the galactanases but not by the glucanases. The results indicate that the 1,4-β-galactanases and the endo-1,3-β-glucanase are likely to be involved in degradation of host cell walls in development of Botrytis rot of apples, but the participation of the last one is not important. We suggest that the secretion of glucanases might be mostly connected with lysis of the fungal cells.