Haploid and Doubled Haploid Platforms for Wheat Improvement: Methods and Applications

Haploid and doubled haploid (DH) technologies are important tools for accelerated wheat (Triticum aestivum L.) breeding, enabling the rapid production of fully homozygous lines and increasing the efficiency of genetic analysis of complex traits. This review presents a comprehensive analysis of the main approaches to producing haploid and DH wheat plants, with particular emphasis on androgenesis-mediated and chromosome elimination methods, including wheat-maize hybridisation. The biological basis of androgenesis is discussed in relation to stress-induced microspore reprogramming; however, the primary focus is on the methodological factors determining the efficiency of DH production, including the donor plant genotype, microspore development stage, pretreatment conditions, composition of the induction and regeneration media, and chromosome doubling. However, its widespread application remains limited by pronounced genotypic dependence, low responsiveness of many commercial varieties, albinism, and a lack of universally effective protocols. In contrast, distant hybridisation systems, particularly wheat-maize hybridisation, are generally characterised by greater reproducibility and less genotypic dependence, although they remain labour-intensive and require precise embryo rescue and chromosome doubling procedures. Overall, further progress in producing DH in wheat will be associated with the optimisation of protocols for difficult-to-respond genotypes and the integration of classical haploidisation systems with omics approaches, genomic selection, and genome-editing.