Response of antioxidative enzymes to plum pox virus in two apricot cultivars

Recent evidence has indicated that activated oxygen species (AOS) may funct ion as molecular signals in the induction of defence genes. In the present work, the response of antioxidative enzymes to the plum pox virus (PPV) was examined in two apricot (Prunus armeniaca L.) cultivars, wh ich behaved differently against PPV infection, In the inoculated resistant cultivar (Goldrich), a decrease in catalase (CAT) as well as an increase in total superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) act ivities were observed, Ascorbate peroxidase (APX), glutathione reductase (G R) and monodehydroascorbate reductase (MDHAR) did not change significantly in relation to non-inoculated (control) plants, In the susceptible cultivar (Real Fine), inoculation with PPV brought about a decrease in CAT, SOD and GR, whereas a rise in APX, MDHAR and DHAR activities was found in comparis on to non-inoculated (control) plants, Apricot leaves contain only CuZn-SOD isozymes, which responded differently to PPV depending on the cultivar, Goldrich leaves contained 6 SODs and both SOD 1 and SOD 2 increased in the inoculated plants, In leaves from Real Fi ne, 5 SODs were detected and only SOD 5 was increased in inoculated plants, The different behaviour of SODs (H2O2-generating enzymes) and APX (an H2O2- remover enzyme) in both cultivars suggests an important role for H2O2 in th e response to PPV of the resistant cultivar, in which no change in APX acti vity was observed, This result also points to further studies in order to d etermine if an alternative H2O2-scavenging mechanism takes place in the res istant apricot cultivar exposed to PPV, On the other hand, the ability of t he inoculated resistant cultivar to induce SOD 1 and SOD 2 as well as the i mportant increase of DHAR seems to suggest a relationship between these act ivities and resistance to PPV, This is the first report about the effect of PPV infection on the antioxida tive enzymes of apricot plants, It opens the way for the further studies, w hich are necessary for a better understanding of the role of antioxidative processes in viral infection by PPV in apricot plants.