Segregation distorters are curious, evolutionarily selfish genetic elements, which distort Mendelian segregation in their favor at the expense of others. Those agents include gametocidal factors (Gc), which ensure their preferential transmission by triggering damages in cells lacking them via chromosome break induction. Hence, we hypothesized that the gametocidal system can be adapted for chromosome manipulations between Triticum and Secale chromosomes in hexaploid triticale (×Triticosecale Wittmack). In this work we studied the little-known gametocidal action of a Gc factor located on Aegilops geniculata Roth chromosome 4Mg. Our results indicate that the initiation of the gametocidal action takes place at anaphase II of meiosis of pollen mother cells. Hence, we induced androgenesis at postmeiotic pollen divisions (via anther cultures) in monosomic 4Mg addition plants of hexaploid triticale (AABBRR) followed by production of doubled haploids, to maintain the chromosome aberrations caused by the gametocidal action. This approach enabled us to obtain a large number of plants with two copies of particular chromosome translocations, which were identified by the use of cytomolecular methods. We obtained 41 doubled haploid triticale lines and 17 of them carried chromosome aberrations that included plants with the following chromosome sets: 40T+Dt2RS+Dt2RL (5 lines), 40T+N2R (1), 38T+D4RS.4BL (3), 38T+D5BS-5BL.5RL (5), and 38T+D7RS.3AL (3). The results show that the application of the Gc mechanism in combination with production of doubled haploid lines provides a sufficiently large population of homozygous doubled haploid individuals with two identical copies of translocation chromosomes. In our opinion, this approach will be a valuable tool for the production of novel plant material, which could be used for gene tracking studies, genetic mapping, and finally to enhance the diversity of cereals.
Double haploids (DH), obtained during androgenesis in vitro or by genome diploidisation in regenerated haploids, are one type of basic materials used in triticale breeding programmes. The aim of this study was to improve DH production by a combination of colchicine treatment methods on a sample of five winter and five spring triticale hybrids. Colchicine was applied in vitro either in the C17 medium to induce embryo-like structures (ELS) or in the 190-2 medium for green plant (GP) development. Regenerants which remained haploid were immersed in a colchicine solution either when placed on the medium prior to transferring to soil or when growing in pots, followed by the application or absence of cooling. Colchicine treatment during anther culture affected neither ELS nor GP development, but significantly increased the number of DH plants in comparison to spontaneous chromosome doubling. The highest efficiency was recorded when colchicine was applied in the induction medium (55%) versus the regeneration medium (44.5%) or no colchicine treatment (30%). The effectiveness of chromosome duplication in haploid plants ranged from 32 to 64.5% and it was the highest for the treatment on the medium followed by cooling. Individual hybrids differed regarding their capability of regeneration and chromosome doubling, which were consistent only to a low or moderate extent. However, taken together, winter and spring hybrids did not differ significantly. Combined colchicine application resulted in a high yield of DH production, 82.6% for all triticale hybrids, and can provide a considerable number of fertile DH lines for triticale breeding programmes.Electronic supplementary materialThe online version of this article (doi:10.1007/s13353-016-0387-9) contains supplementary material, which is available to authorized users.
The main aim of this work was to induce the chromosome rearrangements between Aegilops ovata (UUMM) and hexaploid triticale (AABBRR) by expression of the gametocidal factor located on the chromosome 4M. The Aegilops ovata × Secale cereale (UUMMRR) amphiploids and triticale ‘Moreno’ were used to produce hybrids by reciprocal crosses. Chromosome dynamics was observed in subsequent generations of hybrids during mitotic metaphase of root meristems and first metaphase of meiosis of pollen mother cells. Chromosomes were identified by genomic in situ hybridisation (GISH) and fluorescence in situ hybridisation (FISH) using pTa71, pTa791, pSc119.2 and pAs1 DNA probes. It has been shown that the origin of the genetic background had an influence on Aegilops chromosome transmission. Moreover, it has been reported that the preferential transmission of chromosome 4M appeared during both androgenesis and gynogenesis. It is also hypothesised that the expression of the triticale Gc gene suppressor had an influence on the semi-fertility of hybrids but did not inhibit the chromosome rearrangements. This paper also describes the double haploid production, which enabled to obtain plants with two identical copies of triticale chromosomes with translocations of Aegilops chromatin segments.
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