Interspecific Hybridization and Resistance Breeding in Vegetables: Genetic Bases, Methods, and Applications of Gene Transfer from Wild Relatives

Abstract

Interspecific hybridization in vegetables is an indispensable breeding strategy for broadening the genetic base of cultivars and transferring valuable resistance genes from wild relatives. In the face of global climate change, increasing population, and food security pressures, developing vegetable cultivars resistant to biotic and abiotic stresses has become one of the most critical goals of modern breeding. However, intensive breeding programs and selection pressure have led to a narrowing of the genetic base in many vegetable species; the absence of resistance genes against diseases and pests in cultivars has caused serious losses in production. In this chapter, the genetic and taxonomic foundations of interspecific hybridization in vegetables, the concept of the gene pool, pre- and post-fertilization hybridization barriers, methods for overcoming these barriers (embryo rescue, somatic hybridization, bridge crossing, ploidy manipulation, and amphiploidy), and concrete application examples from different vegetable families (Solanaceae, Brassicaceae, Cucurbitaceae, Alliaceae, Asteraceae, Fabaceae) are discussed. Qualitative and quantitative resistance mechanisms, the role of molecular markers and the GISH technique, the problem of linkage drag, and solution strategies are examined in detail. In addition, perspectives are presented on the integration of next-generation sequencing technologies, genome editing tools (CRISPR/Cas9), and genomic selection into interspecific hybridization programs and on the future development of new vegetable cultivars resistant to climate change, diseases, and pests.