Flax for oil or fibre? Morphometric analysis of flax seeds and new aspects of flax cultivation in Late Neolithic wetland settlements in southwest Germany

The transition from the early to the middle phase of the Late Neolithic (fourth–third millennium b.c.) is closely connected with the term “secondary products revolution”, which involves the adoption of animal traction and an increased production of rendered animal commodities such as wool and dairy products. Based on measurements of Linum usitatissimum L. (flax) seeds and their abundance in 32 wetland settlements in southwest Germany, we presume that the introduction of a new flax variety, maybe a better flax for fibre, and the intensification of flax cultivation were also a part of this process. The morphometric analysis shows that flax seed sizes in the early phase of the Late Neolithic (4000–3400 cal. b.c.) differ significantly from those of the middle and latest phase (3400–2400 cal. b.c.).     

Botanical analysis of a bundle of flax (Linum usitatissimum L.) from an early medieval site in northern Poland; a contribution to the history of flax cultivation and its field weeds

A bundle of flax (Linum usitatissimum L.) radiocarbon dated to 1210±70 uncal B.P. (830±90 cal A.D.) was analysed for its macrofossil content. Apart from stems, capsules and seeds of flax., a large number of diaspores (fruits and seeds) from other plants was identified. Field weeds were the most numerous taxa present, among them three flax field weeds,Spergula maxima, Camelina alyssum andCuscuta cpilinum. Development of the specific flax weed community is discussed. Indicator values are used to characterize the edaphic conditions of this early medieval flax field. The field weeds spectrum also suggests that this flax was sown as a summer crop after an earlier crop of millet.     

Plant economy at a late Neolithic lake dwelling site in Slovenia at the time of the Alpine Iceman

We present the results of a plant macroremain study of the late Neolithic lakeshore settlement Stare gmajne (SG) at Ljubljansko barje, Slovenia, with cultural horizons that ended around 3330 and 3110 cal. b.c., as obtained by dendrochronological and radiocarbon dating of the most frequent construction timbers of Quercus sp. (oak) and Fraxinus sp. (ash). Fourteen systematically taken samples were investigated, using standard methods for studying waterlogged plant remains, which had been developed during lake dwelling research north of the Alps. Most of the remains were preserved in a waterlogged state, and we identified a total of 93 taxa. The most important cultivated plants were Triticum dicoccum (emmer), Hordeum vulgare (six-rowed naked barley), T. monococcum (einkorn), Linum usitatissimum (flax) and Papaver somniferum (opium poppy). The numerous possibly gathered plants also included Trapa natans (water chestnut) and Vitis vinifera ssp. sylvestris (wild grapevine). Chenopodium album (goosefoot) and Brassica rapa (turnip) with seeds/fruits rich in oil and starch were probably gathered as well. Comparisons of the Stare gmajne results with contemporary north Alpine sites (NA) showed, among other things, that Triticum durum/turgidum (tetraploid naked wheat), frequent at NA, was not found at SG. Trapa natans (water chestnut) was rare and Vitis (grapevine) was not found at NA. The observed differences in the wild plant spectra may have ecological causes, for example a warmer climate south of the Alps, but differences in cultivar spectra are more likely for cultural-historical reasons.     

Retting pits for textile fibre plants at Danish prehistoric sites dated between 800 b.c. and a.d. 1050

During the last decade, a new type of structure has been found at several archaeological sites in Denmark. These structures can be interpreted as having been used for retting the stems of textile plants such as Linum usitatissimum L. (flax), Cannabis sativa L. (hemp) and Urtica dioica L. (nettle). In order to obtain fine threads for textile production, these plants need to pass through several biological and technical processes. The first process is the retting of the plant stems to dissolve the pectin which fixes the fibres to the stalk. This can either be done by water retting, where the plant stems are soaked in lakes, rivers or waterlogged pits, or by field retting, where the stems are laid out in a field in order to absorb dew. The first method is shorter in time and the process is easier to control. In this article, details of archaeological structures are presented from eight sites in southern Scandinavia that can be interpreted as textile plant retting pits. The constructions of the pits are described, as well as the archaeological contexts and the relevant associated archaeobotanical records. Some of the presented sites, of which the oldest are dated to the late Bronze Age and early pre-Roman Iron Age (800–250 b.c.) and the youngest to the Viking Age (a.d. 750–1050), indicate a large-scale production of flax that had been underestimated up to now.     

Flax in Sweden: the archaeobotanical, archaeological and historical evidence

The earliest recorded evidence of flax being cultivated in Sweden is from the end of the Bronze Age/beginning of the Iron Age. Later, from ca. a.d. 1100 and onwards, flax became an economically important plant in the country, and during the 12th to 16th centuries there was a substantial increase in the Swedish export of linen to other parts of Europe. Alongside its extensive cultivation, a set of cultural traditions and rituals was eventually built up around flax. The objective of this article is to draw an outline of the history of flax cultivation in Sweden and to present the relevant prehistoric and historic source material. A point of discussion will be the different roles that fibre flax and oil flax played over a long period of time and the problem of seed corn import for the development of domestic fibre flax in the country. The study is based on the prehistoric archaeobotanical record, mainly charred seeds from the Swedish Iron Age (ca. 500 b.c.–a.d. 1050), the archaeological record, documentary evidence and folklore.     

Flax cultivation and textile production in Neolithic wetland settlements on Lake Constance and in Upper Swabia (south-west Germany)

At present there are substantial amounts of archaeological and archaeobotanical data from the Late Neolithic wetland settlements of southern Germany on the oil and fibre plant flax (Linum usitatissimum L.). This is the result of 30 years of intensive excavations and research in 53 settlement areas. This article, on the one hand, will present the significance of flax remains, products made of flax and the inventory of relevant tools for evidence of and reconstruction of the flax production processes. On the other hand, based on the quantitative analysis of flax remains, the changing significance of this important cultivated plant during the course of the Late Neolithic will be demonstrated. From this it will be evident that textile production and in particular flax processing were part of a decisive upheaval in cultural development that initiated the transition to the middle phase of the Late Neolithic in the fields of agriculture and technology.     

Historical and botanical evidence of distribution, cultivation and utilization of Linum usitatissimum L. (flax) in China

Linum usitatissimum L. (flax) has been cultivated for more than 2,000 years in China. Throughout the history of its cultivation, flax was mainly used for oil and medicine. It was not until the last 100 years that fibre flax began to be cultivated and used. This paper discusses the distribution, cultivation and use of flax in China especially in the past, based on literature reviews and ethnobotanical surveys for its traditional uses. The modern distribution of wild flax species in China is also presented in this paper.     

TECHNICAL ADVANCE: Transformation of the flax rust fungus,Melampsora lini: selection via silencing of an avirulence gene

Rust fungi cause devastating diseases on many important food crops, with a damaging stem rust epidemic currently affecting wheat production in Africa and the Middle East. These parasitic fungi propagate exclusively on plants, precluding the use of many biotechnological tools available for other culturable fungi. In particular the lack of a stable transformation system has been an impediment to the genetic manipulation required for molecular analysis of rust pathogenicity. We have developed an Agrobacterium‐mediated genetic transformation procedure for the model flax rust fungus Melampsora lini, which infects flax (Linum usitatissimum). Selection of transgenic rust lines is based on silencing of AvrL567, which encodes a rust effector protein that is recognised by the flax L6 immune receptor. The non‐transgenic rust line is unable to infect flax plants expressing L6, while silenced transgenic lines are virulent on these plants, providing an effective selection system. This directly confirms that the cloned AvrL567 gene is responsible for flax rust virulence phenotypes, and demonstrates the utility of this system to probe rust gene function.     

Isolation and characterization of microsatellite loci from the rust pathogen,Melampsora lini

We developed and characterized primers for 11 variable microsatellite loci present in the genome of the flax rust, Melampsora lini. The microsatellite loci were identified by sequencing clones from a library of EcoRI DNA fragments enriched for four simple sequence repeat motifs (AAG, AAT, TC and TG). All 11 primer pairs successfully amplified DNA fragments from a sample of 102 M. lini isolates (98 isolated from Linum marginale and four from Linum usitatissimum), revealing a total of 32 alleles. Allelic diversity at the 11 loci ranged from 0.030 to 0.449.     

Floral-Dip Transformation of Flax (Linum usitatissimum) to Generate Transgenic Progenies with a High Transformation Rate

Agrobacterium-mediated plant transformation via floral-dip is a widely used technique in the field of plant transformation and has been reported to be successful for many plant species. However, flax (Linum usitatissimum) transformation by floral-dip has not been reported. The goal of this protocol is to establish that Agrobacterium and the floral-dip method can be used to generate transgenic flax. We show that this technique is simple, inexpensive, efficient, and more importantly, gives a higher transformation rate than the current available methods of flax transformation.In summary, inflorescences of flax were dipped in a solution of Agrobacterium carrying a binary vector plasmid (T-DNA fragment plus the Linum Insertion Sequence, LIS-1) for 1 - 2 min. The plants were laid flat on their side for 24 hr. Then, plants were maintained under normal growth conditions until the next treatment. The process of dipping was repeated 2 - 3 times, with approximately 10 - 14 day intervals between dipping. The T1 seeds were collected and germinated on soil. After approximately two weeks, treated progenies were tested by direct PCR; 2 - 3 leaves were used per plant plus the appropriate T-DNA primers. Positive transformants were selected and grown to maturity. The transformation rate was unexpectedly high, with 50 - 60% of the seeds from treated plants being positive transformants. This is a higher transformation rate than those reported for Arabidopsis thaliana and other plant species, using floral-dip transformation. It is also the highest, which has been reported so far, for flax transformation using other methods for transformation.     

Cultivation and processing of Linum usitatissimum and Camelina sativa in southern Scandinavia during the Roman Iron Age

Charred seed conglomerates of Linum usitatissimum (flax) and Camelina sativa (gold of pleasure) were found at Uppåkra 2:25, a Roman Iron Age site in Skåne, southern Sweden. The conglomerates showed no mixing with each other, as they were almost pure flax and gold of pleasure respectively. Together with other archaeobotanical data from the site, they provide new evidence on the use, processing and cultivation of these two plants in early Iron Age in Scandinavia. Metric analyses were applied to flax seeds from both conglomerates and other contexts at this site, and compared to seed assemblages from other Roman Iron Age sites in Europe. The comparison showed that the flax cultivation at Uppåkra 2:25 was intended for the production of oil-rich seeds. The contextual relationship indicates that both flax and gold of pleasure seeds were processed in a similar way and used for oil. Furthermore, the pure seed conglomerate of gold of pleasure suggests that this plant was not a weed, but rather an intentionally grown crop which was cultivated separately from flax.     

Induced albina mutations as a tool for genetic analysis and cell biology in flax (Linum usitatissimum)

In order to obtain nuclear recessive albina mutants, seeds ofLinum usitatissimum ‘Antares’ were treated withethyl methanesulphonate (EMS) for 4 h at a concentration of0.5% (v/v). After the mutagenic treatment, the M₁ seeds weresown in the greenhouse, selfed and the resulting M₂ seeds ofeach M₁ plant were harvested separately. Observation of albinamutants in the M₂ generation facilitated the estimation of thegenetically effective cell number (GECN). In flax, four cellscontribute to the formation of the inflorescence. The transmissionof the albinism trait was further analysed in the progeny derivedfrom the albina mutants. In four of these mutants, the albinismcharacter was found to be encoded by recessive nuclear genes.The utility of these mutants as a source of regenerating explantsor of protoplasts was tested. These features are critical tothe development of interspecific hybrids in flax by creatinga universal hybridizer which carries a positive and dominanttrait (e.g. resistance to an antibiotic) and a recessive trait(e.g. nuclear recessive albinism). Key words: Albinism, ethyl methanesulphonate mutagenesis, genetically effective cell number, Linum usitatissimum     

RNAi-mediated pinoresinol lariciresinol reductase gene silencing in flax (Linum usitatissimum L.) seed coat: Consequences on lignans and neolignans accumulation

RNAi technology was applied to down regulate LuPLR1 gene expression in flax (Linum usitatissimum L.) seeds. This gene encodes a pinoresinol lariciresinol reductase responsible for the synthesis of (+)-secoisolariciresinol diglucoside (SDG), the major lignan accumulated in the seed coat. If flax lignans biological properties and health benefits are well documented their roles in planta remain unclear. This loss of function strategy was developed to better understand the implication of the PLR1 enzyme in the lignan biosynthetic pathway and to provide new insights on the functions of these compounds. RNAi plants generated exhibited LuPLR1 gene silencing as demonstrated by quantitative RT-PCR experiments and the failed to accumulate SDG. The accumulation of pinoresinol the substrate of the PLR1 enzyme under its diglucosylated form (PDG) was increased in transgenic seeds but did not compensate the overall loss of SDG. The monolignol flux was also deviated through the synthesis of 8-5′ linked neolignans dehydrodiconiferyl alcohol glucoside (DCG) and dihydro-dehydrodiconiferyl alcohol glucoside (DDCG) which were observed for the first time in flax seeds.     

The diet of Eneolithic (Copper Age, Fourth millennium cal b.c.) pile dwellers and the early formation of the cultural landscape south of the Alps: a case study from Slovenia

Analyses were performed of plant remains from the Late Neolithic (in Slovenian terminology corresponding to Eneolithic or Copper Age, ca. 4300–2300 b.c.) pile dwelling Hočevarica in the Ljubljansko barje (Ljubljana Moor), Slovenia. This settlement existed between ca. 3650 and 3550 cal b.c. Seeds, fruits, wooden piles, macroscopic charcoal and pollen from the cultural layers were analysed. The remains of domestic plants such as charred grains of Hordeum vulgare (barley), Triticum monococcum, T. dicoccum (einkorn and emmer wheat) and Papaver somniferum (poppy seeds), as well as seeds of weeds such as Chenopodium album-type indicate early cultivation in the area. In addition, numerous remains of nuts and berries, especially of Quercus sp., Cornus mas, Rubus fruticosus and Corylus avellana demonstrate that the gathering of wild plants was an important part of subsistence. Palaeoecological and archaeobotanical data from Hočevarica further suggest that cleared land was used for agriculture and pastures during the Neolithic, and that different wood was cut for construction and for fuel. The species assemblage from Hočevarica is very similar to those recovered from northern Alpine lake dwelling sites, however, several new taxa (e.g. Lathyrus sativus, Vicia sp.) appear in the assemblage. One of the most surprising finds is the seed of wild grape (Vitis vinifera ssp. sylvestris), which are the oldest on-site remains of grapevine from Slovenia.     

An alternative method of flax retting during dry weather

During exceptionally dry and hot weather undesiccated flax (Linum usitatissi-murri) and flax desiccated with glyphosate that was pulled and laid on the ground to dew-ret, retted 1–2 wk before flax that was desiccated and left as a standing crop. This was because dew-retted flax was colonised by fungi faster than that left standing. Cladosporium herbarum, Epicocum nigrum and yeast, including Aureoba-sidium pullulans, appeared first; they were followed by Alternaria alternata, Fusarium culmorum and Phoma, Mucor and Rhizopus species. The standing crop retted more slowly despite the presence of greater concentrations of cell-wall degrading enzymes. However, the fibres of flax retted as a standing crop retained more of their strength than those of flax retted on the ground. Thus dew-retting provides means of retting when the weather is dry and hot.     

Lignans in seeds of Linum species

Mature seeds of 20 Linum species were analyzed for their content of lignans. The seeds of common flax (Linum usitatissimum L.) are known to contain as characteristic lignan sesoisolariciresinol diglucoside (SDG), whose presence in seeds of some other Linum species has also been reported. In order to investigate the material for the presence of such very polar lignans as well as for less polar non-glycosidic lignans as frequently found in aerial parts of Linum species, polar and non-polar extracts of each sample were analyzed by HPLC/ESI-MSMS.SDG was detected in 15 of 16 investigated seed samples of taxa representing sections Linum and Dasylinum. None of eight samples of taxa from sections Syllinum and Linopsis contained detectable amounts of SDG. Quite interestingly, most of the SDG-positive samples contained the 8R,8′R-isomer exclusively while only three (including L. usitatissimum) contained the 8S,8′S-stereoisomer as the predominant form. As a most noteworthy finding, the dichloromethane extracts obtained from seeds of several Linum species were found to contain significant concentrations of non-polar cyclolignans of the arylnaphthalene/-dihydronaphthalene lactone type or, alternatively of the aryltetralin lactone type. Thus, seeds of Linum perenne L. as well as those of several other representatives of sections Linum and Dasylinum were found to contain significant concentrations of the arylnaphthalene justicidin B along with further compounds of this type and some aryldihydronaphthalene-type lignans. On the other hand, seeds of Linum flavum and further representatives of section Syllinum were found to contain aryltetralin-type lignans, mainly in the form of esters with aliphatic carboxylic acids, such as 6-methoxypodophyllotoxin-7-O-n-hexanoate, whose occurrence in L. flavum seeds has very recently been reported by us for the first time.Various chemosystematic and biogenetic aspects are discussed in the light of these results.     

亚麻主要农艺与品质相关性状的QTL定位

为了全面了解亚麻产量和品质相关性状的遗传基础,为亚麻基因克隆和分子标记辅助育种提供理论依据,在已构建SNP连锁遗传图谱的基础上,以LH-89为父本,R43为母本构建F2:3家系QTL定位群体,用R/QTL软件采用复合区间作图法对13个农艺和品质性状进行QTL定位。结果表明:(1)该研究共检测出35个QTL位点,与粗脂肪及其组成成分相关的QTL有20个,与农艺性状相关的QTL有15个;其中:亚油酸和粗脂肪各5个,亚麻酸、千粒重各4个,棕榈酸、株高、工艺长度各3个,硬脂酸、分枝数各2个,单株果数、果粒数、单株粒重、油酸各1个。(2)共有18个QTL的表型贡献率超10%(主效基因),其中农艺性状定位8个主效基因,品质性状定位10个主效基因。     

Notes on the genusLinum in Madagascar

Linum emirnense Bojer subsp.marojejyense Humb. is elevated to a species and the heterostylous condition thought to exist inL. emirnense is determined to be an artifact resulting from a fungal infection of the fruit.