Aggressiveness and production of cell-wall degrading enzymes by Pythium violae, Pythium sulcatum and Pythium ultimum, responsible for cavity spot on carrots

摘要: This study investigated the relationships between pathogenesis, types of symptoms and in vitro production cell-wall degrading enzymes by P. violae, sulcatum ultimum. The three pathogens, considered as Pythium species principally responsible for cavity spot on carrot roots, secreted only low levels fatty acid esterases activity, suggesting they have limited ability to degrade suberin walls outer cell layers tissues. Among that polysaccharides, pectate lyases cellulases were produced these late small amounts: caused violae typical spot. Conversely, ultimum maceration tissues, polygalacturonases β-1,4-glucanases earlier larger amounts than violae. also a large diversity proteins cellulase isoenzymes. Although secreting all monitored higher quantity two previous species, was spot, with brown colouring. role plant reactions induced response early pectinolytic enzyme may account this apparent inconsistency.