Incompatibility Alleles in Portuguese Hazelnut Landraces

In many higher plants, selffertilization and genetically related individuals are prevented by pollen-stigma incompatibility. In the genus Corylus, incompatibility is of the sporophytic type and controlled by a single locus with multiple alleles. The objective of this study is to identify the S-alleles present in a collection of Portuguese landraces in order to select the most appropriate landraces for establishment of future orchards and for breeding programmes. Ten major Portuguese hazelnut landraces were submitted to controlled pollinations in the field, with 18 genotypes whose S-alleles are known. The pollen tubes were observed at 100X under a florescence microscope to evaluate their development. Three landraces were revealed to have S2 allele, two have S5, and four have one of the S3, S5, S10, and S18 alleles. One landrace was compatible with the 18 S-alleles tested and for two landraces, it was possible to identify both alleles. The information of the self-incompatibility relationship between these old cultivars is obviously useful for selecting the most suitable pollinators for planning new orchards and for new cultivars development.