Linum Bienne Research Articles

Ex situ collections of cultivated flax (Linum usitatissimum L.) and other species of the genus Linum L.

An overview of ex situ collections of cultivated flax (Linum usitatissimum L.) and 53 other species of the genus Linum L. is presented. The names of 33 genebanks in 23 countries preserving Linum germplasm and the species preserved at these places are provided. World genebanks engage in ex situ preservation of about 48,000 accessions of cultivated flax (Linum usitatissimum). However, possibly only 10,000 accessions of these are unique. Of the ca. 200 species of the genus Linum, other than L. usitatissimum, 53 are reported to be represented in the world’s ex situ collections with a total of about 900 accessions. Of these, 279 accessions alone refer to the wild progenitor of cultivated flax, Linum bienne Mill. However, L. bienne from the region of origin of cultivated flax is rarely represented in genebank collections. References to publications describing the techniques for ex situ conservation and the infraspecific variation of cultivated flax are made. It is suggested that taxonomic species delimitation within the genus Linum is in need of clarification and that the variation in Linum species for ornamental use or use in breeding is investigated.

Evidence of the domestication history of flax (Linum usitatissimum L.) from genetic diversity of the sad2 locus

A phylogenetic analysis was conducted on 34 alleles of 2.5 kb sized stearoyl-ACP desaturase II (sad2), obtained from 30 accessions of cultivated and pale flax (Linum spp.), to elucidate the history of flax domestication. The analysis supports a single domestication origin for extant cultivated flax. The phylogenetic evidence indicates that flax was first domesticated for oil, rather than fibre. The genetic diversity of the sad2 locus in cultivated flax is low when compared to that of the pale flax assayed. An absolute archaeological date could be applied to the synonymous substitution rate of sad2 in cultivated flax, yielding a high estimate of 1.60-1.71x10(-7) substitutions/site/year. The occurrence of nonsynonymous substitutions at conserved positions of the third exon in alleles from cultivated flax suggests that the locus may have been subjected to an artificial selection pressure. The elevated synonymous substitution rate is also compatible with a population expansion of flax since domestication, followed by a population decline in historic times. These findings provide new insight into flax domestication and are significant for the continuous exploration of the flax germplasm for utilization.

Variation of cultivated flax (Linum usitatissimum L. subsp.usitatissimum) and its wild progenitor pale flax (subsp.angustifolium (Huds.) Thell.)

The domestication of cultivated flax (Linum usitatissimum L. subsp.usitatissimum) is briefly discussed. Using data documented as a matter of routine in genebank work, 63 accessions of cultivated flax from the flax germplasm collection of the Gatersleben Genebank are compared with 73 accessions of its wild progenitor pale flax (subsp.angustifolium (Huds.) Thell.), which have been observed in systematic field trials. Range of variation, genetically based variation, heritability and correlation of several characters are considered, especially with respect to the influence of domestication. Cultivated flax shows higher variation in the characters of generative plant parts, while pale flax varies more in the vegetative parts of the plant. The character correlations are similar in both subspecies. Of the 29 characters studied in pale flax the parameters describing tillering, height of plant, weight of seeds, width of petals and width of leaves are especially suitable for distinguishing between different accessions. In spite of the high heritabilities of most of the characters, the influence of the environment is significant in most cases.

STUDIES IN THE VEGETATIONAL HISTORY OF MID‐WALES

SUMMARYStratigraphic and pollen evidence is presented from a mire site on the eastern side of the main Cambrian watershed of central Wales. A complex basin contains Late Devensian lake sediments overlain by Flandrian organic detritus muds. Organic lake muds were replaced by swamp and carr vegetation on the north and west of the site, but the south‐east basin continued as a lake until relatively recent times (the last 200 years). Final colonization of the lake was by a floating raft of Carex rostrata, Menyanthes trifoliata and Sphagnum cuspidatum, on which the present sphagnum‐dominated vegetatiiin has developed. Such schwingmoor mire types are uncommon in Britain and this is a particularly good example.Pollen analysis of the Flandrian lake sediments provides information concerning vegetational history. Interesting early Flandrian records are of Hippophäe rhamnoides. Linum bienne and Fumaria. Pinus sylvestris has low pollen levels in the early Flandrian, unlike many western sites. It is suggested that sites having high values may have Pinus as a local mire colonist. The Ulmus decline is very marked and is accompanied by evidence of cultivation. This is the first evidence of cereal growing in early Neolithic times in Central Wales. Higher in the profile Cannabis saliva assumes importance, possibly as a result of Iron Age/Roman cultivation.

Træk af høravlens historie

Træk af høravlens historie