The present invention relates to methods for controlling hybridization in plants and producing hybrid plants. The present invention also relates to nucleic acids encoding amino acid sequences for self-incompatibility (SI) proteins in plants, and the use thereof for the manipulation of SI, including seed production, in plants, particularly of the Poaceae family. The present invention also relates to kits, compositions, constructs and vectors including such nucleic acids, and related polypeptides, regulatory elements and methods. The present invention also relates to expression of self-gamete recognition genes in plants and to related nucleic acids, constructs, molecular markers and methods.