Genotypic Variation for Hordeum bulbosum L.-Mediated Haploid Production in Winter and Facultative Barley
The use of Hordeum bulbosum L.-mediated haploid production in barley (Hordeum vulgare L.) germplasm enhancement, gene mapping, and marker-assisted selection is limited by low efficiencies of haploid production with certain barley genotypes. The primary objective of this study was to assess genotypic variation for haploid production efficiency in an array of 10 winter and facultative barley cultivars of diverse geographic origin. Another objective was to compare in vitro floret and tiller culture as aids to haploid production by the bulbosum method. There was significant genotypic variation for haploid production efficiency (HPE), computed as the number of haploid plants regenerated/100 florets pollinated with both techniques. The highest HPE (48) was achieved with ‘Schuyler’ using floret culture, a technique in which barley florets pollinated with H. bulbosum L. are cultured on modified N6 media containing 0.5 mg L−1 kinetin and 1.2 mg 2,4-D L−1. Mean HPEs achieved with floret and tiller culture were 35 and 15, respectively. Cultivars exhibited differential HPE response. Of the components of haploid production efficiency (seeds/100 florets, embryos/100 seeds, and plants/100 embryos), a significant genotype ✕ culture technique interaction was found only for embryos/100 seeds. The use of floret culture as an aid to H. bulbosum L.-mediated haploid production should facilitate barley germplasm enhancement, mapping, and selection efforts requiring routine doubled haploid synthesis from genetically broadbased germplasm arrays.
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