Number Of Haploid Plants Research Articles

In vitro anther culture and Agrobacterium-mediated transformation of the AP1 gene from Salix integra Linn. in haploid poplar (Populus simonii × P. nigra)

A reliable, efficient anther culture system, the dominant technique for generating haploid plants in breeding programs, that can be used for generating transgenic poplar plants has been needed. In the present study, therefore, an anther culture system was developed using isolated mid- and late-uninucleate anthers of poplar (Populus simonii × P. nigra). From a combination of SSR and ploidy analyses, six double haploid and two haploid lines were characterized from 86 plants grown from 16 regenerated anther cultured lines. After 48 months of development, two plant lines from the regenerated plants maintained their haploid level in vitro for over 2 years. A number of haploid plants from the different lines were transferred to soil. The leaves of these transplants were then used as explants for transformation with the APETALA1 (AP1) gene using Agrobacterium tumefaciens. Overexpression of AP1 in haploid poplar induced early flowering with obvious petals when ectopically expressed. To our knowledge, this is the first report on changes in flowering time in AP1-trangenic poplar, which is important for elucidating the regulatory mechanism of tree flower development.

Androgenesis Induced in <i>Nicotiana alata</i> and the Effect of Gamma Irradiation

Nicotiana alata anthers cultured on different modified media based on MS, MT and N were used to obtain haploid plants through direct and indirect ways. The haploid plants resulting on MS medium ranged from 52% - 80%, on MT medium ranged from 32% - 52% and on N medium ranged from 28% - 44%. Accordingly, the best medium used for haploid induction was MS supplemented with 0.2 mgl-l NAA + 0.5 mgl-l KIN. On the other hand, MS medium supplemented with 0.4 mgl-l NAA + 0.5 mgl-l KIN or 1.0 mgl-l BAP + 0.5 mgl-l NAA were the best mediums for callus induction and plant regeneration, respectively. Morphologically, the leaf size, stem highest and diameter, flower size and diameter, anther length and number were about 67% of the diploid plants growth. Irradiated anthers with doses of 0, 2.5, 5, 7.5, 10, 15, 20 and 25 Gy caused reducing the number of haploid plants with increasing gamma radiation dose. For the haploid plants irradiated with same doses, the mortality percentage of bud survival was increasing with increasing gamma radiation dose. The irradiated callus with doses of 0, 5, 10, 15 and 20 Gy was affected negatively on growth rate and morphology. Proline content in irradiated plantlets increased with increasing gamma radiation dose. As well, total soluble protein content was increased with gamma irradiation up to 10 Gy. However, the higher doses caused a severe decrease of total soluble proteins. The production of proline and total soluble proteins in haploid plants were 48.6% and 69.5%, respectively comparing with diploid plants.

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.