Incompatibility in fruit tree species: S-locus structure and molecular mechanism of pistil and pollen determinants.

Fruit tree species in the Rosaceae family have a gametophytic self-incompatibility system mediated by S-RNase; this mechanism provides specific recognition between pollen and pistil, mediated by female proteins (S-RNase) and male proteins (F-box proteins) codified by the single multigenic S locus. In recent years, above all due to developments in molecular biology, research in this sector has clarified many aspects relating to the structure and functioning of the S locus. The additional understanding has important applications, including molecular assays to determine the S genotype and assisted selection to obtain self-fertile varieties, already possible for many fruit tree species.