Journal of Plant Pathology Archive

Abstract:

Results of a six-year evaluation carried out in the Czech Republic (CR) for resistance of apricot cvs Harlayne and Betinka to six different strains and isolates of PPV are presented. Two-year-old trees of both cultivars were inoculated by chip budding with PPV-M (type strain), PPV-D (type strain), PPV-Rec (originally recovered in the CR as PPV-W), PPV-M (isolated in the CR from peach), PPV-D (isolated in the CR from Prunus insititia), and PPV-Rec (isolated in the CR from P. insititia). PPV susceptible apricot cvs Karola and Velkopavlovická were used as controls and were chip-bud inoculated with PPV strains. No symptoms appeared in the leaves and fruits of cv. Betinka during six years of observation following inoculation with PPV-D (type), PPV-D (P. insititia), PPV-Rec (PPV-W), PPV-M (peach) and PPVRec strains, and in two trees inoculated with PPV-M (type) strain. Likewise, ELISA did not detect the presence of PPV in the leaves of both cultivars. RT-PCR gave a slight positive reaction from the leaves of a symptomless tree of cv. Harlayne inoculated with PPV-Rec (PPV-W) and from leaves of a symptomless tree of cv. Betinka inoculated with PPV-D (P. insititia). The presence of PPV in these trees is under investigation. Mild diffuse rings and spots appeared occasionally in the leaves and fruits of one tree of cv. Betinka after inoculation of PPV-M (type). The presence of PPV was confirmed by ELISA and RT-PCR. The relative concentration of PPV-M (type) protein in the leaves of a tree of cv. Betinka determined by ELISA was low (2.5×10-1) in comparison with the control (cv. Karola, 1.95×10-3). Severe symptoms appeared in the leaves and fruits of susceptible control cvs Karola and Velkopavlovická. The presence of different PPV strains in control cultivars was confirmed by ELISA and RTPCR. Thus, cvs Harlayne and Betinka displayed durable resistance to the six different strains and isolates of PPV over the six year trial.