Recent advances in generation of doubled haploid plants for genetic improvement in solanaceous vegetable crops

Genotype-specific protocols and advancements focusing on CRISPR/Cas9-based haploid induction for doubled haploid (DH) production are poised to revolutionize plant breeding for faster genetic improvement in solanaceous crops. The need for swift development of improved cultivars offering greater resilience to biotic and abiotic stresses stems from the emergence of climate change risks. While conventional methods are effective, novel methods for precise crop genome manipulation are required. The in vivo and in vitro protocols leading to fixation of homozygosity and rapid attainment of homozygous DH (doubled haploids) lines have led to a resurgence in research on haploids and DH. The efforts for haploid production have been primarily concentrated on in vitro androgenesis and gynogenesis. The success of these in vitro techniques depends on various parameters, including culture conditions, developmental stage of the microspore, pretreatment, culture medium, growth regulators, and other media additives. Breakthroughs in genome-editing technologies, such as the CRISPR/Cas9 (Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9) system, have provided a new avenue for exploring in vivo haploid embryogenesis for haploid induction by means of haploid inducer factors, such as DMP (DMP domain of unknown function 679 membrane protein), ECS (egg cell-specific), MTL (matrilineal), and BBM (Baby boom). A successful haploid induction system in vegetable crops will be possible through the development of efficient in vivo and in vitro androgenesis and gynogenesis protocols. For genome-editing to be feasible, protocols must be optimized for commercially significant solanaceous crops like pepper, potatoes, eggplant, and tomatoes. The existing protocols for genome doubling need to be further improved for solanaceous crops. These developments are pivotal for the advancement and harnessing of haploid technology to its full potential in crop breeding.