GAMMA-RAY-INDUCED CHANGES IN THE SYNTHESIS OF TOMATO PERICARP PROTEIN

The application of massive doses of gamma rays (1-8 kGy) to mature gre en cherry-tomato fruits led to a transient fall in pericarp tissue pro tein metabolism within 6 h. A separate 3 kGy treatment resulted in the appearance of certain transcripts and proteins, and a reduction in th e abundance of others. At the same dose, protein synthesis regained th e control level within 24 h, and in addition a new set of proteins was induced. Gamma-induced proteins (referred to as GIPs) were divided in to three groups, depending on the time-course of their induction. Grou p 1 GIPs were synthesized only during the first few hours following tr eatment, whereas group 2 GIPs were synthesized for at least 48 h. Grou p 3 GIPs were progressively induced when the control level of synthesi s was restored. These results demonstrated that, despite its deleterio us effects on DNA and cell structures, irradiation induced an active r esponse in plant tissue. Comparative experiments suggest that the majo rity of group 1 GIPs might belong to the heat shock protein family. GI Ps might play a role in the protection and repair of cellular structur es, or may be implicated in physiological disorders triggered by irrad iation.