S-genotyping of sweet cherry varieties from Spain and S-locus diversity in Europe

Sweet cherry is a traditional fruit crop in Spain. The introduction of modern cultivars is replacing the local varieties and genetic diversity is lost. To conserve this plant material, local varieties are being collected and characterized. As part of this objective we investigated the S-genotype of 73 local varieties. S-locus analysis was carried out by PCR analysis of S-RNase and SFB genes. PCR was done using conserved primers and fragments detection was carried out by capillary electrophoresis. Fifty-six cultivars were S-genotyped for first time and 17 had been S-RNase typed previously. The S-genotype of the 73 varieties was unambiguously determined. Ten different S-haplotypes were identified: S (1) , S (2) , S (3) , S (4) , S (5) , S (6) , S (9) , S (13) , S (16) and S (22) . The varieties were assigned to 17 incompatibility groups, to Group '0' of universal donors, and to Group 'SC' of self-compatible varieties. The results provide cross-compatibility information for cross design and orchard management. The results also reveal the S-locus diversity of this plant material. S-haplotypes S (3) , S (6) and S (22) were the most frequent and S (16) was only found in the Balearic Islands. Comparison of S-haplotype frequencies worldwide and within Europe showed that S (22) is almost exclusive of southern Europe. Other S-haplotypes that are common in northern Europe, like S (2) , S (4) , S (5) , were rare in the southern plant material. This geographic distribution of S-haplotypes across Europe may indicate a common origin or genetic relationship of varieties from close areas. Alternatively, there may be an association of certain S-haplotypes with adaptive traits correlated to climatic conditions in the different areas.