Multi-resistance of apricot cultivars to the most important diseases in Spain

Spain is one of the most important producers of fresh apricots. Traditional production was based on several local cultivars of good quality and well adapted to industry demands. Nevertheless, most of these cultivars are susceptible to important diseases that affect production and fruit quality. These diseases are sharka (Plum pox virus; PPV), viruela (Apple chlorotic leaf spot virus; ACLSV), and fruit degeneration disease (Hop stunt viroid; HSVd). In the Department of Plant Breeding of CEBAS-CSIC, we study these diseases, looking for sources of resistance to be used in breeding programmes. Using foreign sources of resistance to PPV, our department has released new cultivars with excellent agronomic behaviour that are widely cultivated in our country and abroad today. More recently, we have identified two new sources of resistance to ACLSV. We are combining traditional breeding methods with molecular markers to study the interactions among the resistance to these different pathogens with the objective of accumulating both types of resistance in good-quality cultivars. ACLSV-resistant sources were crossed with PPV-resistant selections homozygous for PGS1.21 and PGS1.24 markers, linked to PPV resistance. Descendants obtained are being evaluated against PPV and ACLSV separately as well as against both diseases simultaneously, in order to detect possible interactions. Despite much work, we have not yet identified sources of resistance to HSVd within apricot species to date, although this deficiency will be addressed by looking for such sources in wild relative apricot species.