RESUMEN
To create a framework for genetic dissection of hexaploid triticale, six populations of doubled haploid (DH) lines were developed from pairwise hybrids of high-yielding winter triticale cultivars. The six populations comprise between 97 and 231 genotyped DH lines each, totaling 957 DH lines. A consensus genetic map spans 4593.9 cM is composed of 1576 unique DArT markers. The maps reveal several structural rearrangements in triticale genomes. In preliminary tests of the populations and maps, markers specific to wheat segments of the engineered rye chromosome 1R (RM1B) were identified. Example QTL mapping of days to heading in cv. Krakowiak revealed loci on chromosomes 2BL and 2R responsible for extended vernalization requirement, and candidate genes were identified. The material is available to all parties interested in triticale genetics.
RESUMEN
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.
Asunto(s)
Cromosomas de las Plantas/genética , Hibridación Genética , Fitomejoramiento/métodos , Translocación Genética , Triticale/genética , Cruzamientos Genéticos , Polen/genética , Poliploidía , Secale/genéticaRESUMEN
Androgenesis using amphidiploid cultivars of Festuca pratensis x Lolium multiflorum as parents, overcame earlier problems that gave rise to widespread plant sterility amongst androgenic Festulolium populations. Two Festuca pratensis x Lolium multiflorum (2n = 4x = 28) cultivars, Sulino and Felopa, were highly amenable to androgenesis and 10% of plants, including some novel androgenic genotypes, had sufficient fertility to produce progeny and further generations. The genomes of amphidiploid cultivars, which represent the F8 generation, were the result of considerable intergeneric chromosome recombination. Moreover, during cultivar development, natural and breeders' selection pressures had led to the assembly of gene combinations that conferred good growth characters and fertility with the removal of putative deleterious gene combinations. Over 80% of the androgenic plants derived from the amphidiploid F. pratensis x L. multiflorum (2n = 4x = 28) had 14 chromosomes and were likely to be dihaploids with a single genome of Lolium and of Festuca. In contrast, hybrids of F. pratensis x L. multiflorum (2n = 2x = 14) found naturally are invariably sterile. Structural reorganization within the genomes of the androgenic Festulolium plants had restored fertility in genotypes expected to contain the haploid genome of Lolium and Festuca. This provided opportunities for their future incorporation in breeding programmes and the development of fertile diploid Lolium-Festuca hybrids. Amongst the androgenic plants, Festulolium genotypes were recovered that conferred excellent drought resistance or freezing tolerance and were thought to be highly suitable for entry into plant breeding programmes.