Molecular cytogenetic identification and phenotypic description of a new synthetic amphiploid, Triticum timococcum (AtAtGGAmAm)

Abstract

A recently developed synthetic amphiploid, Triticum timococcum Kost., nom. nud. (2n = 6x = 42, AtAtGGAmAm) is described in the present study. This hexaploid taxon was developed by colchicine treatment in Martonvásár from the hybrid of a selected accession of Triticum timopheevii Zhuk. (2n = 4x = 28, AtAtGG) and a prebred semi-dwarf line of Triticum monococcum L. (2n = 2x = 14, AmAm). A detailed cytomolecular examination was carried out using the sequential multicolour fluorescence and genomic in situ hybridization techniques (FISH and mcGISH). It was proved that T. timococcum has 42 chromosomes originating from its parents. The chromosomes of the A genomes of T. monococcum and T. timopheevii could be distinguished in the amphiploid using FISH. The successful discrimination of the chromosomes was supported by the karyotypes of the three genomes and the successful optimization of the mcGISH technique for the A and G chromosomes achieved in the present study. A phenotypic evaluation was also carried out under natural and artificial growing conditions in 2012 and 2013. Based on the results, T. timococcum has intermediate characteristics in terms of spike (spikelet) shape and plant height, while it is similar to the female parent, T. timopheevii regarding pubescence. Like its parents, T. timococcum showed outstanding resistance to the main fungal diseases of wheat. T. timococcum headed later and developed longer and looser spikes, fewer tillers and only a third as many seeds than its parents. The third generation of T. timococcum was able to develop an acceptable number of seeds, even taking into account the reduced germination ability in the field.

Development and characterisation of interspecific hybrid lines with genome-wide introgressions from Triticum timopheevii in a hexaploid wheat background

“…Firstly, it was confirmed that the FISH karyotype of the T. timopheevii accession used in this work was similar to a previously published karyotype for T. timopheevii (Fig. 4b; [37]). Differences between the FISH signals of wheat (Fig.…”

“…Oligos pSc119.2–1 (green) and the Afa family (red) were used as FISH probes. a known FISH karyotype of wheat [56] ( b ) FISH karyotype of T. timopheevii accession P95–99.1-1 (based on that published by [37]) ( c ) FISH karyotype of line BC 3 F 2 –114-1 showing a homozygous introgression from T. timopheevii linkage group 5G into wheat chromosome 5B ( d ) FISH signals in the metaphase spread of line BC 3 F 2 –114-1 used to make the karyotype with white arrows indicating chromosomes T5GS.5GL-5BL ( e ) GGT bar diagram of line BC 3 F 2 –114-1 showing the T. timopheevii introgression from linkage group 5G in red markers while the wheat alleles are represented in blue…”

Genetic Diversification and Dispersal of Taro (Colocasia esculenta (L.) Schott)

“…In the Pacific, where all cultivars are diploids, many cultivars flower naturally, insect pollinators are very active, and natural hybridization among cultivars occurs regularly [ 4 ], so the clonal richness index is very high even though the genetic diversity is narrow. This has been reported in Vanuatu where 209 taro cultivars collected from six villages located on different islands had a clonal richness index of 0.83 [ 44 ]. In Africa, the clonal richness was not similar among countries analyzed and two groups could be distinguished: Réunion and Madagascar where the number of cultivars was low but, the clonal richness index between 0.3 and 0.5.…”

“…The histogram showed a valley between the first peak corresponding to the cultivars sharing the same MLG or those which differ by very few mutations and the second peak corresponding to the distances between cultivars derived from independent sexual reproduction events. Such valley was then used as reliable indicator for the threshold distance required to assign MLGs into distinct (MLLs) [ 44 ]. The MLGs grouped together, below the given threshold of difference, were assigned to distinct MLLs, while distinct MLGs above the threshold, were considered as unique genotypes (UG).…”

Dissecting the U, M, S and C genomes of wild relatives of bread wheat (Aegilops spp.) into chromosomes and exploring their synteny with wheat

“…Chromosome preparations were examined under a Zeiss AxioImager M2 fluorescence microscope system equipped with an AxioCam MRm CCD camera (Zeiss, Oberkochen, Germany), and the images were compiled with AxioVision v4.8 software (Zeiss) as described by Mikó et al . (). After capturing FISH signals on metaphase plates, the slides were washed and re‐hybridized with GAA and ACG microsatellite probes at 42°C using the protocol described above.…”