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

The metabolic changes in tomato fruits and seeds separately infected with cucumber mosaic virus, Pseudomonas syringe pv. tomato or Botrytis cinerea were investigated cytochemically. The changes of peroxidase (E.C. 1.11.1.7) and 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 value. Tomato seeds were investigated since they have been used most extensively as a model system for studying the physiology and biochemistry of seed development. The diseases caused by the pathogens under study are of special importance for yield reduction in tomato. The three pathogens provoked local changes in the activities of enzymes under study that affect the infected 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 tissues 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 enhancement of or-galactosidase activity in infected area was observed. The specific responses depending on the type of the pathogen consisted in an enhancement of glucose-6-phosphate dehydrogenase activity by virus infection and an increase of beta-glucosidase activity by fungal invasion.