Doubled Haploid Rice Breeding

Rice (Oryza sativa L.) is a vital component of global food security, sustaining one-third of the world’s population. The Oryza genus encompasses 24 species, with Oryza sativa and Oryza glaberrima being cultivated. Due to the challenges posed by climate change and the depletion of natural resources, there is an urgent need for extensive research to enhance rice yield and quality. Traditional breeding methods, involving continuous selfing over generations, are labor-intensive and time-consuming, prompting the adoption of Doubled Haploid (DH) technology. DH technology rapidly fixes desired genes in the immediate generation, offering a solution to challenges faced by rice breeders. The process involves producing haploids from hybrids through anther, pollen, or ovule culture, doubling the chromosomes, and resulting in stable and fertile plants. Various methods contribute to haploid induction in rice, including in vitro-based approaches (anther culture, microspore culture, and ovary culture) and in vivo methods (distant hybridization, CENH3-mediated, and HIS). The in vitro-based approach involves challenges such as early anther necrosis and poor callus response in indica rice varieties. Microspore culture refines anther culture by isolating microspores, while ovary culture explores inducing haploids from unpollinated ovaries. In vivo methods present promising alternatives, with genome editing technologies enhancing their applicability. Diploidization of haploids can be achieved through spontaneous or artificial doubling agents. Characterizing DH lines involves analyzing ploidy, phenotype, pollen determination, cytology, isozyme markers, and DNA markers. DH technology finds diverse applications, including accelerating breeding cycles, mapping genes for qualitative and quantitative traits, studying genetic modifications, conserving germplasm, and developing biotic and abiotic stress-tolerant lines. The versatility of DH technology significantly contributes to advancing rice breeding, ensuring timely delivery of improved cultivars to meet the increasing global demand for rice sustainably.