Breaking self-incompatibility for diploid hybrid potato breeding: advances, mechanisms, and emerging technologies

Potato (Solanum tuberosum L.) is a staple food crop vital to global food security. Conventional tetraploid potato breeding is severely constrained by tetrasomic inheritance, long breeding cycles, low propagation efficiency, and accumulated genetic load. Diploid hybrid breeding based on homozygous inbred lines represents a promising strategy to restructure potato improvement. However, most diploid potatoes exhibit strong gametophytic self-incompatibility, which blocks the development of inbred lines and limits hybrid breeding. In recent years, remarkable progress has been made in elucidating the molecular basis of potato self-incompatibility, including the S-locus, S-RNase, SLF/SFB genes, and the pivotal S-locus inhibitor gene. Meanwhile, innovative strategies including S-locus inhibitor gene introgression, genome editing, haploid induction and apomixis have facilitated the development of homozygous inbred lines and hybrid breeding and the development of homozygous inbred lines. This mini review systematically summarizes recent advances in the molecular mechanisms of potato self-incompatibility, key technologies to overcome self-incompatibility, and innovative diploid hybrid breeding paradigms. We further propose integrated strategies combining precision genome editing, speed breeding, and apomixis to accelerate hybrid variety development, offering a practical guide for diploid hybrid potato improvement.