Toward Doubled Haploid Production in the Fabaceae: Progress, Constraints, and Opportunities

The Fabaceae species have a major role to play in sustainable farming systems, but they have lagged behind other families in respect to the development of doubled haploid protocols for plant improvement. Currently, no plant improvement program uses doubled haploids on a routine basis for any member of the Fabaceae. There has recently been renewed interest in haploid research as the usefulness of doubled haploid material in molecular mapping has become clear. This review provides a comprehensive account of the current information regarding the development of haploid protocols in the Fabaceae. In the Fabaceae crop species there have been isolated reports of haploid plant induction in the phaseoloid clade; soybean, cowpea and pigeonpea, as well as promising progress towards haploidy in peanut and winged bean. As yet there have been no reports of haploid plant production in the galegoid clade, but early stage haploid embryogenesis has been achieved in chickpea, field pea, and lupin. Success in the production of haploid plants has also been reported within the pasture genera Lotus, Medicago, and Trifolium and the arboreal genera Cassia, Peltophorum, and Albizzia. A review of the literature has enabled us to identify some general similarities between the protocols developed for haploid plant induction across the various legumes. These are the culture of intact anthers; use of a cold pretreatment to induce sporophytic development; targeting of microspores at the uninucleate stage of development; and use of MS (Murashige and Skoog, 1962 Murashige, T. and Skoog, F. 1962. A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol. Plant., 15: 473–497. [CSA][Crossref], [Web of Science ®] , [Google Scholar]) based nutrient medium with plant growth regulators to encourage continued division following induction. These protocol commonalities will assist researchers to identify approaches suited to their target Fabaceae species. The paucity of research funding for haploid research in most Fabaceae species has highlighted the need for strong collaborative linkages between institutions and researchers.