PLANT CELL BIOTECHNOLOGY AND MOLECULAR BIOLOGY

Hybrid breeding is an important approach for improving productivity, uniformity, quality, and adaptability in vegetable crops. This review discusses the genetic and genomic mechanisms used to support hybrid development, with emphasis on heterosis, self-incompatibility, male sterility systems, gynoecism, and recent molecular breeding tools. Heterosis provides a practical basis for exploiting superior performance in hybrid progenies, particularly for yield, earliness, stress tolerance, and marketable traits. However, efficient hybrid seed production depends on reliable control of self-pollination and pollen fertility. Self-incompatibility promotes cross-pollination by preventing self-fertilisation and is useful in crops such as Brassica vegetables and radish. Male sterility systems, including genetic, cytoplasmic, and cytoplasmic-genic male sterility, reduce the need for manual emasculation and support large-scale hybrid seed production in several vegetable crops. Gynoecism is especially valuable in cucurbits because the predominance of female flowers improves hybrid seed production efficiency and fruiting potential. The review also highlights the role of marker-assisted selection, genomic analysis, genome-wide association studies, genomic selection, gene editing, tissue culture, doubled haploid technology, and protoplast fusion in improving breeding precision. These tools help identify fertility-related genes, maintain sterile lines, select restorers, and accelerate the development of superior hybrids. Despite these advances, hybrid breeding still faces challenges such as environmental sensitivity of sterility systems, complex inheritance of heterosis, high technology costs, and regulatory concerns related to advanced biotechnological approaches. The integration of conventional breeding with molecular and genomic tools can improve the reliability, efficiency, and sustainability of hybrid vegetable breeding programmes.