Molecular and biological assessment reveals sources of resistance to Plum pox virus - Turkey strain in Turkish apricot (Prunus armeniaca) germplasm

Plum pox virus (PPV) is an important threat to apricot (Prunus armeniaca) production globally, including in Turkey and Iran, the world's leading producers of dried apricots. Although most apricot cultivars are susceptible and host resistance is the most promising approach to managing the disease. A few cultivars carrying the resistance locus PPVres have been used in breeding programs. Additional sources of resistance are highly desirable. The PPV susceptibility of cultivars in the Irano-Caucasian eco-geographical group, considered a secondary center of apricot diversity, has been little studied. We surveyed the response of 227 apricot accessions to PPV strain 'Turkey' (PPV-T) and, in parallel, scored molecular markers linked to PPVres. Four accessions ('Cebir', 'Lifos' 'Karum', and 'Zard') were identified as resistant to PPV-T and carried molecular markers for PPVres. Two additional accessions ('Kanis', and Italian Cultivar 'Fracasso') were resistant but did not carry any of the PPVres resistance markers, indicating possible new sources of resistance. Their novelty was also supported by previously published molecular diversity analyses. The new resistance sources will be particularly useful for breeding new cultivars of apricot for drying. The marker ZP002 is more reliable and easy to use in selecting for the resistance allele at the PPVres locus. PPV resistance in apricot is not likely strain-specific