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Saskatoon, Canada

Diederichsen A.,Plant Gene Resources of Canada | Solberg S.O.,Nordic Genetic Resource Center | Jeppson S.,Nordic Genetic Resource Center
Genetic Resources and Crop Evolution | Year: 2013

A descriptor list of 34 phenological and morphological characters was applied to assess the changes of diversity in 57 Nordic spring wheat (Triticum aestivum L.) cultivars released between 1892 and 1994 and to compare their diversity to 22 Nordic landraces. The field observations were conducted at the Nordic Genetic Resource Centre at Alnarp, Sweden, in 2010. Over time the cultivars became shorter, less inclined to lodging, earlier in heading and maturity. The spikes became shorter and denser with more grains per spikelet, and seed shattering of mature spikes decreased. The morphological type of Nordic spring wheat cultivars did not change after the 1960s, although improvements in disease resistances, yield and quality characters still occurred. All recent cultivars represented T. aestivum L. var. lutescens (Alef.) Mansf., characterised by awnless spikes with white glabrous glumes and red grains. Compared to the cultivars, the landraces were generally earlier in heading and maturity, much taller, inclined to lodging and they had looser spikes with less grains per spikelet than cultivars. In some characters such as glume colour and awnedness the landraces showed more diversity within and among the accessions than the cultivars and hence represented more infraspeficic taxa than the cultivars. Nordic landraces seemed adapted to low-input growing conditions. However, for the use in ecological agriculture, they would need improvements, e. g. in reducing seed shattering, lodging and enhancing disease resistances. The role of plant breeding in preserving and developing genetic diversity in Nordic spring wheat with emphasis on Sweden is discussed. © 2012 Her Majesty the Queen in Right of Canada.

Kagale S.,Agriculture and Agri Food Canada | Kagale S.,National Research Council Canada | Robinson S.J.,Agriculture and Agri Food Canada | Nixon J.,Agriculture and Agri Food Canada | And 9 more authors.
Plant Cell | Year: 2014

The Brassicaceae (Cruciferae) family, owing to its remarkable species, genetic, and physiological diversity as well as its significant economic potential, has become a model for polyploidy and evolutionary studies. Utilizing extensive transcriptome pyrosequencing of diverse taxa, we established a resolved phylogeny of a subset of crucifer species. We elucidated the frequency, age, and phylogenetic position of polyploidy and lineage separation events that have marked the evolutionary history of the Brassicaceae. Besides the well-known ancient α (47 million years ago [Mya]) and β (124 Mya) paleopolyploidy events, several species were shown to have undergone a further more recent (~7 to 12 Mya) round of genome multiplication. We identified eight whole-genome duplications corresponding to at least five independent neo/mesopolyploidy events. Although the Brassicaceae family evolved from other eudicots at the beginning of the Cenozoic era of the Earth (60 Mya), major diversification occurred only during the Neogene period (0 to 23 Mya). Remarkably, the widespread species divergence, major polyploidy, and lineage separation events during Brassicaceae evolution are clustered in time around epoch transitions characterized by prolonged unstable climatic conditions. The synchronized diversification of Brassicaceae species suggests that polyploid events may have conferred higher adaptability and increased tolerance toward the drastically changing global environment, thus facilitating species radiation. © 2014 American Society of Plant Biologists. All rights reserved.

Diederichsen A.,Plant Gene Resources of Canada | Kusters P.M.,Plant Gene Resources of Canada | Kessler D.,Plant Gene Resources of Canada | Bainas Z.,Plant Gene Resources of Canada | Gugel R.K.,Plant Gene Resources of Canada
Genetic Resources and Crop Evolution | Year: 2013

Between 1998 and 2008, numerous projects were conducted by the Canadian national genebank, Plant Gene Resources of Canada, for the regeneration, characterization and evaluation of the whole flax (Linum usitatissimum L.) germplasm collection. The whole collection comprised 3378 accessions and, according to the passport data, several of these were probably genetically very similar or even identical. Therefore, a subset of 381 accessions was selected that represented the diversity found in the whole collection. Sampling accessions from the whole collection was made using characterization and evaluation data and followed six different methods: (1) For seven qualitative characters, each unique combination of character expression was represented by three accessions; (2) for quantitative characters, a fixed number of accessions representing the lowest and highest observed values was included; (3) for stem fibre content, disease ratings, seed vigour and drought tolerance, a fixed number of accessions with desirable performance was included; (4) a subset of the 57 most distinct accessions based on RAPD markers was included; (5) a subset of 40 pure lines that were created based on extreme low and high values for 1000 seed weight, seed oil content and fatty acid profiles was included; (6) a subset of fibre flax cultivars of known relevance in European flax breeding and another subset of flax cultivars of known relevance for North American linseed breeding were included. The goal was to maximize the diversity available in a limited number of flax accessions by preserving the range of variation present in the whole collection, while improving evenness. The core collection was assembled in response to requests by flax breeders. This paper compares distribution parameters in the whole and core collections. © 2012 Her Majesty the Queen in Right of Canada.

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