Incompatibility in European Hazelnut Meleksen Akin

Hazelnut (Corylus) Fagales order, Betulaceae family 8 shrub species and 5 tree species European hazelnut (Corylus avellana L.) is most suited to cultivation and crop production

• Monoecious • Dichogamous • Wind pollinated (Corylus avellana L.) • Monoecious • Dichogamous • Wind pollinated

(Corylus avellana L.) Self-incompatible Cross-pollination enforced Sporophytic incompatibility (rejection of self-pollen depends on the diploid genotype of the pollen controlled by a single locus with multiple alleles)

Sporophytic Incompatibility Controlled by S-locus Linkage group 5 33 alleles controlling self-incompatibility Each allele is defined by a number

Sporophytic Incompatibility Dominance or co-dominance in pollen Co-dominance in stigmas If the same allele is expressed by the stigma and the pollen, the cross is incompatible

Sporophytic Incompatibility Example: ‘Lewis’ has S3S8 Female flowers express both of the alleles Male flowers express one of the alleles If the expressed allele by the pollen matches any of the alleles by the female flower, the cross is incompatible

Incompatibility Testing using Fluorescence Microscopy Compatible • Excellent germination • Long parallel tubes Incompatible • Poor germination • Short tubes, bulbs

Self-incompatibility Very low nut sets Blank nuts (shell without a nut) Compatible pollinizer variety required

References S. A. Mehlenbacher References S.A. Mehlenbacher. Geographic distribution of incompatibility alleles in cultivars and selections of European hazelnut. J Amer Soc Hort Sci. 139. 191–212 (2014). J. Olsen. Pollination and nut development. In: Growing hazelnuts in the Pacific Northwest. Oregon State University Extension Service Corvallis (2013). http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/43809/em9074.pdf M.M. Thompson. Genetics of incompatibility in Corylus avellana L. Theor Appl Genet. 54. 113-116 (1979).