The origin of the self‐compatible almond ‘Supernova’

The almond cultivar ‘Supernova’ is reported in the literature as a late‐flowering self‐compatible mutant, obtained by the irradiation of the early‐flowering self‐incompatible cultivar ‘Fascionello’. Our work to investigate the molecular basis of this form of self‐compatibility has called into question the origin of ‘Supernova’. Test selfing was performed both on ‘Supernova’ and on the accession of ‘Fascionello’ from which it was derived –‘Fascionello‐Rome’. Both proved self‐compatible. Amplification of S ‐ RNase alleles, using consensus primers from the signal peptide region to the second conserved region of the S ‐ RNase gene and primers specific for allele S f , confirmed ‘Supernova’ and ‘Fascionello‐Rome’ indeed have the same (in)compatibility genotype S 1 S f as the self‐compatible cultivar ‘Tuono’. Nine microsatellite markers were used to fingerprint the relevant accessions; ‘Supernova’ and ‘Fascionello‐Rome’ were undistinguishable from ‘Tuono’. Two Sicilian accessions, ‘Fascionello’ and ‘Falso Fascionello’, lacked S f and differed at the SSR level, indicating no close relationship with ‘Supernova’. Therefore we concluded that ‘Fascionello‐Rome’ is actually the same as ‘Tuono’ and that ‘Supernova’ originates from ‘Tuono’ from which it derives its self‐compatibility.