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.