Metabolic changes in tomato fruits and seeds after viral, bacterial and fungal infections

The metabolic changes in tomato fruits and seeds separately infected with c ucumber mosaic virus, Pseudomonas syringe pv. tomato or Botrytis cinerea we re investigated cytochemically. The changes of peroxidase (E.C. 1.11.1.7) a nd beta-glucosidase (E.C. 3.2.1.21) were investigated biochemically as well . Tomato fruits were involved in the study because of their high economic v alue. Tomato seeds were investigated since they have been used most extensi vely as a model system for studying the physiology and biochemistry of seed development. The diseases caused by the pathogens under study are of speci al importance for yield reduction in tomato. The three pathogens provoked l ocal changes in the activities of enzymes under study that affect the infec ted pericarp tissues and neighboring seeds. It was established non-specific and specific responses. The non-specific responses of invaded tissues were expressed as a local enhancement of peroxidase activity in both pericarp t issues and seeds as well as a decrease in activities of: i. enzymes taking part in aerobic and anaerobic respiration, ii. hydrolases esterase and acid phosphatase involved in the basic metabolism as well as an enhancement of their activities in neighboring tissues. Furthermore. it was observed an en hancement of or-galactosidase activity in infected area was observed. The s pecific responses depending on the type of the pathogen consisted in an enh ancement of glucose-6-phosphate dehydrogenase activity by virus infection a nd an increase of beta-glucosidase activity by fungal invasion.