Evaluation of some Prunus rootstocks to natural infection to Plum pox virus in endemic area

L.A. Zagrai, I. Zagrai, G. Guzu
Plum pox virus (PPV), which causes Sharka disease, is considered the most detrimental viral pathogen affecting Prunus spp. Rootstock resistance is very important for PPV containment strategies, given that rootstock suckers represent gateways for the virus inoculum, mediated by aphid vectors. Different types of myrobalan rootstocks are frequently used for some Prunus spp. Myrobalan BN 4Kr is a mutant of Prunus cerasifera developed as resistant to PPV, and hence it has great potential for reducing the impact of PPV. The aim of this study was to evaluate the response of BN 4Kr in comparison with two commonly-used plum rootstocks, Myrobalan 29C and St. Julien, to high natural infection pressure in a PPV-endemic area. Two field trials were established in an experimental nursery with nearby PPV inoculum sources, and without any phytosanitary treatments. The first field trial with BN 4Kr and St. Julien rootstocks was established in 2014 and a second one, with BN 4Kr and Myrobalan 29C, in 2016. Plants were grown in pots and prior to field planting were tested to check their PPV free status. PPV symptoms on leaves were evaluated twice every vegetative period. Serological and molecular tools were used to evaluate the rate of infections with PPV of the investigated rootstocks. Typical PPV symptoms were observed on Myrobalan 29C and St. Julien, but not on BN 4Kr. DAS-ELISA and IC-RT-PCR tests revealed a high infection rate of PPV on Myrobalan 29C and St. Julien rootstocks, while no BN 4Kr plants became infected during two or four years of field testing. The results suggest that the resistance of BN 4Kr against PPV in field condition of endemic area remained stable and durable, and hence has potential for wider use.
Zagrai, L.A., Zagrai, I. and Guzu, G. (2020). Evaluation of some Prunus rootstocks to natural infection to Plum pox virus in endemic area. Acta Hortic. 1269, 97-104
DOI: 10.17660/ActaHortic.2020.1269.13
DAS-ELISA, IC-RT-PCR, Prunus cerasifera, nursery, resistance, sharka

Acta Horticulturae