EVALUATION OF THE SUSCEPTIBILITY OF DIFFERENT PRUNUS ROOTSTOCKS TO NATURAL INFECTION OF PLUM POX VIRUS-T

Abstract

SUMMARY Plum pox virus (PPV) has been observed in Turkey since 1968, but was not widespread except in apricot and plum trees in home gardens and ornamental parks in restricted areas. Susceptibility of six different Prunus rootstocks to strain PPV-T was assessed under natural inoculum pressure in the Izmir-Aegean region during 2010-2011. Aphid populations were monitored from the first week of April to the middle of June by the stickyplant method one year after the rootstock plantation was established. Aphids collected from different rootstocks were tested individually by squash real-time RT-PCR and all rootstocks were regularly tested by DASI-ELISA. The largest aphid populations were observed at the end of May and the most abundant aphid species as averages over the two years were Myzus persicae (20.15%), Hyalopterus pruni (18.64%), Aphis craccivora (9.04%) and Aphis gossypii (8.36%). In 2011, the highest percentage of viruliferous aphids was found in M. persicae (34.78%), followed by H. pruni (32.50%), Macrosiphum euphorbiae (25.00%), A. gossypii (23.80%), A. spiraecola (12.50%) and A. craccivora (10.00%). Of the six Prunus rootstocks tested, only Nemaguard and Myrobalan 29C were infected by PPV-T, infection rate in 2010 being 6.0% (Nemaguard) and 4.0% (Myrobalan 29C). The infection rate increased to 16.0% for Nemaguard and 14.0% for Myrobalan 29C in 2011. However, the other rootstocks, Prunus marianna GF8.1, Docera6, GF677 and Garnem tested negative for PPV-T throughout 2011. PPV isolates obtained from naturally infected apricot trees (inoculum source) and from infected rootstocks in the experimental plot were characterized as PPV-T and had more than 99.5% nucleotide sequence identity.