Effect of tobamovirus infection on thermoluminescence characteristics of chloroplasts from infected plants

Changes of thermoluminescence characteristics as well as the O-2-evolving c apacity was analysed in chloroplasts isolated from Nicotiana benthamiana in fected with pepper and paprika mild mottle viruses and their chimeric hybri ds. The electron transport activity in thylakoids of virus-infected plants was inhibited and could be restored by adding DPC or Ca2+ which indicated t hat the virus infection altered the oxygen-evolving complex. In thermolumin escence characteristics of plants infected with either viruses, the first w ell defined response was a shift in the peak position of the B band from 20 degrees C to 35 degrees C corresponding to S-3(S-2)Q(B)(-) and S(2)Q(B)(-) charge recombinations, respectively, which showed an inhibition in the for mation of higher S states in the water splitting system. Simultaneously, a new band appeared around 70 degrees C due to chemiluminescence of lipid per oxidation. Further progress of the viral infection dramatically decreased t he intensity of bands originated from charge recombinations with a concomit ant increase of the band at 70 degrees C indicating the general oxidative b reakdown of injured thylakoids.