Role of carbohydrates in early metabolic reactions of germinating lupin seeds infected with Fusarium oxysporum f.sp. lupini

Abstract

Soluble carbohydrates, particularly oligosaccharides, can take pan in defense responses preventing and restricting fungal pathogen invasion. Morphological changes were observed and ß-glucosidase activity was studied in yellow lupin embryo-axes infected and uninfected with <i>F.oxysporum</i> and cultured for 24 to 96 hours under conditions of a varying carbohydrate supply. The first disease symtoms - necrotic pathological changes were observed 48 hours after the inoculation. A higher intensity of the disease changes as well as growth restriction were found in 72- and 96-h embryo axes growing under carbohydrate deficiency. The activity of â-glucosidase increased during 24 - 96 hours after inoculation. An especially high increase of the activity was noted in 72- and 96-h embryo axes cultured under carbohydrate deficiency. We suggest that sugars are involved in the mechanisms of yellow lupin embryo axis tissues resistance, since they constitute the source of precursors for the synthesis of antimicrobial factors of plant defense response.