RAPD markers for self-incompatibility in Corylus avellana L.

We used a bulked segregant analysis approach in a population of 84 hazelnut (Corylus avellana L.) seedlings of the cross OSU 316.139 (S1S6) x OSU 265.096 (S3S4) in an attempt to identify random amplified polymorphic DNA (RAPD) markers linked to incompatibility alleles. DNA samples from five trees each were pooled to form bulks for the four S-allele combinations. Superbulks of 10 trees, each devoid of a single allele, were then created. Initial screening of the DNA from parents and superbulks with 460 random primers identified five possible S-allele markers. When the entire population was screened, only one marker, OPN20(1300), was linked to an S-allele. OPN20(1300) was present in all 52 S-3 progeny, and absent in 28 of the 31 non-S-3 individuals, giving a recombination rate of 3.75% in this population. However, OPN20(1300) was not linked to the S-3 allele outside the original population. Work with previously identified RAPD marker OPI07(750) showed that it is an excellent marker for the S-2 allele. This marker was cloned and two pairs of sequence characterized amplified region (SCAR) primers were made. Each pair identified one monomorphic 700 by band in all individuals and another 750 by DNA fragment that co-segregated with the S-2 allele. Attempts to sequence both bands consistently resulted in identical nucleotide sequences. Searches in the Databank revealed 28% identity at the amino acid level to a putative reverse transcriptase from Oryza sativa and to a reverse transcriptase domain from Arabidopsis thaliana. Efforts are underway to characterize the S-2 marker and determine its usefulness in cloning the self-incompatibility locus.