Regulation of endopolygalacturonase gene expression in Botrytis cinerea bygalacturonic acid, ambient pH and carbon catabolite repression

The phytopathogenic fungus Botrytis cinerea produces a set of endopolygalac turonases (endoPGs) which are involved in the enzymatic degradation of pect in in plant cell walls. The endoPG-encoding genes of B, cinerea are differe ntially expressed when the fungus is grown in liquid culture on different c arbon sources. A basic constitutive expression level was observed for two g enes, Bcpg1 and Bcpg2, which encode basic isozymes, Galacturonic acid was s hown to induce the expression of Bcpg4 and Bcpg6. Low pH of the culture med ium resulted in induced expression of the Bepg3 gene. Expression of the Bcp g5 gene was inducible, however the inducing factors could not be identified . Finally, galacturonic acid-induced expression of the Bcpg4 gene was repre ssed by the presence of more-favourable carbon sources, such as glucose.