Plant Gene Resources Of Canada Research Articles

Flax for seed or fibre use? Flax capsules from ancient Egyptian sites (3rd millennium BC to second century AD) compared with modern flax genebank accessions

AbstractIn order to determine whether ancient Egyptians had already selected and cultivated very specialized flax types according to their purpose for textile or oil production, respectively, we compared archaeobotanical flax finds with nearly 3000 diverse genebank accessions kept at the Plant Gene Resources of Canada (PGRC). The main result was that fibre flax was most probably already cultivated during the 3rd millennium BC, whereas in later periods an intermediate flax and/or oil type was in use. The collaboration between archaeobotanists and genebank curators shows how our knowledge about ancient usage of plants can be improved by interpreting observations made on ancient findings using recent characterization data obtained from diverse genebank material.

Variability in Maturity, Oil and Protein Concentration, and Genetic Distinctness among Soybean Accessions Conserved at Plant Gene Resources of Canada.

Soybean (Glycine max (L.) Merr.) is one of the important crops in Canada and has the potential to expand its production further north into the Canadian Prairies. Such expansion, however, requires the search for adapted soybean germplasm useful for the development of productive cultivars with earlier maturity and increased protein concentration. We initiated several research activities to characterize 848 accessions of the soybean collection conserved at Plant Gene Resources of Canada (PGRC) for maturity, oil and protein concentration, and genetic distinctness. The characterization revealed a wide range of variations present in each assessed trait among the PGRC soybean accessions. The trait variabilities allowed for the identification of four core subsets of 35 PGRC soybean accessions, each specifically targeted for early maturity for growing in Saskatoon and Ottawa, and for high oil and protein concentration. The two early maturity core subsets for Saskatoon and Ottawa displayed days to maturity ranging from 103 to 126 days and 94 to 102 days, respectively. The two core subsets for high oil and protein concentration showed the highest oil and protein concentration from 25.0 to 22.7% and from 52.8 to 46.7%, respectively. However, these core subsets did not differ significantly in genetic distinctness (as measured with 19,898 SNP markers across 20 soybean chromosomes) from the whole PGRC soybean collection. These findings are useful, particularly for the management and utilization of the conserved soybean germplasm.

Patterns of Genetic Variation in a Soybean Germplasm Collection as Characterized with Genotyping-by-Sequencing.

Genomic characterization is playing an increasing role in plant germplasm conservation and utilization, as it can provide higher resolution with genome-wide SNP markers than before to identify and analyze genetic variation. A genotyping-by-sequencing technique was applied to genotype 541 soybean accessions conserved at Plant Gene Resources of Canada and 30 soybean cultivars and breeding lines developed by the Ottawa soybean breeding program of Agriculture and Agri-Food Canada. The sequencing generated an average of 952,074 raw sequence reads per sample. SNP calling identified 43,891 SNPs across 20 soybean chromosomes and 69 scaffolds with variable levels of missing values. Based on 19,898 SNPs with up to 50% missing values, three distinct genetic groups were found in the assayed samples. These groups were a mixture of the samples that originated from different countries and the samples of known maturity groups. The samples that originated from Canada were clustered into all three distinct groups, but 30 Ottawa breeding lines fell into two groups only. Based on the average pairwise dissimilarity estimates, 40 samples with the most genetic distinctness were identified from three genetic groups with diverse sample origin and known maturity. Additionally, 40 samples with the highest genetic redundancy were detected and they consisted of different sample origins and maturity groups, largely from one genetic group. Moreover, some genetically duplicated samples were identified, but the overall level of genetic duplication was relatively low in the collection. These findings are useful for soybean germplasm management and utilization.

Molecular characterization of soybean (glycine max) accessions from the international collection of the plant gene resources of Canada: germplasm identification

ABSTRACT Soybean (Glycine max) is one of the most important crops in the world in terms of total production and usage. Evaluation of gene bank accessions such as the international collections of soybean (Glycine max) of the Plant Gene Resources of Canada has not been undertaken at the molecular level. The main objectives of the present study were to 1) determine the level of genetic variation and distance among G. max accessions from the international collections of the Plant Gene Resources of Canada and 2) develop and characterize accession-diagnostic inter simple sequence repeat (ISSR) and sequence-characterized amplified region (SCAR) markers that can be used in soybean molecular breeding programs. Genomic DNAs from 108 soybeans (G. max) accessions from 11 different countries were analyzed using ISSR primers. The levels of polymorphic loci detected were in general moderate varying from 29% to 52%. Overall, 82% of genetic distance values among accessions were above 0.40 based on ISSR analysis. This suggests that the genetic diversity among and within soybean accessions might not be as low as other studies have demonstrated. The soybean accessions from the Netherlands, China, France, and Sweden were the least genetically variable. The dendrograms constructed with ISSR data revealed that the South Korean accessions formed an out-group. The ISSR markers successfully distinguished soybean accessions within each group (country). In fact, several accession-diagnostic markers were identified in each of the 11 groups. They represent useful tools in soybean molecular breeding programs. One accession-diagnostic marker was cloned, sequenced, and converted to a SCAR marker.

Genetic Variability of 27 Traits in a Core Collection of Flax (Linum usitatissimum L.).

Assessment of genetic variability of plant core germplasm is needed for efficient germplasm utilization in breeding improvement. A total of 391 accessions of a flax core collection, which preserves the variation present in the world collection of 3,378 accessions maintained by Plant Gene Resources of Canada (PGRC) and represents a broad range of geographical origins, different improvement statuses and two morphotypes, was evaluated in field trials in up to 8 year-location environments for 10 agronomic, eight seed quality, six fiber and three disease resistance traits. The large phenotypic variation in this subset was explained by morphotypes (22%), geographical origins (11%), and other variance components (67%). Both divergence and similarity between two basic morphotypes, namely oil or linseed and fiber types, were observed, whereby linseed accessions had greater thousand seed weight, seeds m−2, oil content, branching capability and resistance to powdery mildew while fiber accessions had greater straw weight, plant height, protein content and resistance to pasmo and fusarium wilt diseases, but they had similar performance in many traits and some of them shared common characteristics of fiber and linseed types. Weak geographical patterns within either fiber or linseed accessions were confirmed, but specific trait performance was identified in East Asia for fiber type, and South Asia and North America for linseed type. Relatively high broad-sense heritability was obtained for seed quality traits, followed by agronomic traits and resistance to powdery mildew and fusarium wilt. Diverse phenotypic and genetic variability in the flax core collection constitutes a useful resource for breeding.

Assembling a core collection from the flax world collection maintained by Plant Gene Resources of Canada

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.

Genetic Diversity in A Core Subset of Wild Barley Germplasm

Wild barley [Hordeum vulgare ssp. spontaneum (C. Koch) Thell.] is a part of the primary gene pool with valuable sources of beneficial genes for barley improvement. This study attempted to develop a core subset of 269 accessions representing 16 countries from the Plant Gene Resources of Canada (PGRC) collection of 3,782 accessions, and to characterize them using barley simple sequence repeat (SSR) markers. Twenty-five informative primer pairs were applied to screen all samples and 359 alleles were detected over seven barley chromosomes. Analyses of the SSR data showed the effectiveness of the stratified sampling applied in capturing country-wise SSR variation. The frequencies of polymorphic alleles ranged from 0.004 to 0.708 and averaged 0.072. More than 24% or 7% SSR variation resided among accessions of 16 countries or two regions, respectively. Accessions from Israel and Jordan were genetically most diverse, while accessions from Lebanon and Greece were most differentiated. Four and five optimal clusters of accessions were obtained using STRUCTURE and BAPS programs and partitioned 16.3% and 20.3% SSR variations, respectively. The five optimal clusters varied in size from 15 to 104 and two clusters had only country-specific accessions. A genetic separation was detected between the accessions east and west of the Zagros Mountains only at the country, not the individual, level. These SSR patterns enhance our understanding of the wild barley gene pool, and are significant for conserving wild barley germplasm and exploring new sources of useful genes for barley improvement.

Phenotypic diversity of Jerusalem artichoke (Helianthus tuberosus L.) germplasm preserved by the Canadian genebank

SUMMARY Jerusalem artichoke ( Helianthus tuberosus L.) originated from the eastern United States and Mexico. Although considerable breeding efforts were made in Europe, the former Soviet Union, and to some degree in Canada, the species remains a neglected crop. Comprehensive characterization data of the genetic resources preserved in different genebanks is rare. A total of 162 Jerusalem artichoke accessions were preserved by Plant Gene Resources of Canada (PGRC) in 2006. This material was agrobotanically characterized in the growing seasons of 2006 and 2008 at Saskatoon, Saskatchewan, Canada. The results of 158 accessions grown in both years were compared. The assessments of variability of 13 rated and 10 measured descriptors for leaf, stem, tuber and phenological characters documented a wide range of phenotypic variation. Repeatability of assessments between the years was generally low, indicating a strong environmental influence on phenotypic diversity. Earliness of flowering, tuber width, tuber weight, tuber shape, tuber epidermis coloration and below-ground growth habit (tubers clustered vs. spread) were the most informative characteristics for describing variation among Jerusalem artichoke accessions. Leaf dimensions and leaf margin serration could also be used to distinguish extreme genotypes. A suggestion for categorizing the PGRC collection into large-tuber and primitive material based on single tuber weight and tuber width is made. Six categories of tuber types based on tuber color and tuber shape are presented.

Duplication assessments in Nordic Avena sativa accessions at the Canadian national genebank

This study applied two methods to assess intra-collection duplication within 339 Nordic oat (Avena sativa L.) accessions preserved by Plant Gene Resources of Canada (PGRC). Putative duplicates, that is accessions carrying a similar accession name, were grouped into 52 duplication groups and included 230 of the 339 Nordic oat accessions. A field assessment based on visual inspection of field plots was conducted during two growing seasons to detect distinct phenotypes within each duplication group. Simultaneously, a descriptor assessment using seven characters with altogether sixteen character states was used in both years for the same purpose. The combined results of both assessments and both years indicated that among the 230 accessions in duplication groups only 118 could be identified as distinct. This would allow for a reduction of 33% of the Nordic oat accessions at PGRC. The field assessment method detected fewer (75%) distinct accessions than the descriptor assessment (84%), when considering all accessions identified as distinct as 100%. Repeatability between years was higher in the field assessment (70%) than in the descriptor assessment (64%). The field assessment requires an experienced germplasm evaluator, but allows for handling large numbers of germplasm accessions and for detecting functional, fitness related, and user-relevant diversity. Combining field assessment with descriptor assessment and more sophisticated methods on selected subgroups may be the most efficient method for determination of internal duplication in genebank collections. Bulking phenotypically similar accessions within duplication groups is preferable to eliminating duplicate accessions when collection rationalization is required, as it reduces the risk of loosing diversity.

Pure-lining of flax (Linum usitatissimum L.) genebank accessions for efficiently exploiting and assessing seed character diversity

Genetic heterogeneity within genebank accessions of a self-pollinating crop has great implications for their preservation, diversity assessment, utilization and exploitation. This study investigated the intra-accession diversity of 38 flax (Linum usitatissimum L.) genebank accessions preserved by Plant Gene Resources of Canada. Seven quantitative seed characters were studied: 1000 seed weight, seed oil concentration and fatty acid proportion of palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2) and α-linolenic acid (18:3). Ten additional morphological characters of high heritability were also recorded. In 13 accessions the intra-accession diversity was assessed based on 4 years of observation of 7-12 pure lines selected randomly from the original accessions. From these 13 accessions, seven showed significant variation among the pure lines for all seven seed characters. In five accessions most seed characters showed significant variation and only in one accession the homogeneity of seed characters dominated. Variation was found in landraces, breeding material and cultivars. In 40 cases an attempt was made to identify pure lines within an accession that significantly exceeded the mean value of the original accession in a seed character, for which the original accession had shown high or low values. In 25 cases and for all seven seed characters such pure lines could be detected. In six cases, the most extreme performing pure lines were not from the same accession, that had the highest or lowest accession mean for the considered character. There was no association of morphological variation with variation of the quantitative seed characters. For genebanks, separation of mixed accessions based on obvious phenotypic diversity and in particular based on characters that create a selective pressure is probably the most efficient way to ensure preservation of a wide range of diversity at reasonable cost. For exploitation of diversity in breeding programmes, pure-lining is very useful.

Variation patterns within 153 flax (Linum usitatissimum L.) genebank accessions based on evaluation for resistance to fusarium wilt, anthracnose and pasmo

Germplasm of 153 flax (Linum usitatissimum) accessions from 24 countries held at Plant Gene Resources of Canada (PGRC) was evaluated for resistance to fusarium wilt (Fusarium oxysporum), anthracnose (Colletotrichum lini) and pasmo (Septoria linicola). The screening was conducted at the All-Russian Flax Research Institute (VNIIL) at Torzhok, Russia, over 3 years for fusarium wilt and anthracnose, and over 2 years for pasmo. A disease severity index ranging from 0% (no infection) to 100% (heavy infection) was calculated based on observations after artificial inoculation with the pathogens in the greenhouse (fusarium wilt) or in field nurseries (anthracnose and pasmo). The average disease severity index for fusarium wilt was 56.6 ± 34.4% (range 0–100.0%), for anthracnose 59.8 ± 8.1% (range 43.8–83.9%) and for pasmo 74.2 ± 11.8% (range 27.3–100.0%). The variation of disease severity indices among the years and within each accession was highest for fusarium wilt. Higher than average resistance for all three diseases was found in accessions from East Asia, while germplasm from the Indian subcontinent showed considerably lower than average resistance. Germplasm from North America and South America (mostly linseed) displayed above average resistance to fusarium wilt, while European accessions (mostly fibre flax) showed lower than average resistance to this disease. The different resistance levels reflected the improvements made by plant breeding and differences in the environments under which the germplasm accessions evolved. Accessions with potential use in linseed and fibre flax breeding were identified.

Assessments of genetic diversity within a world collection of cultivated hexaploid oat (Avena sativa L.) based on qualitative morphological characters

A characterization of 10,105 accessions of hexaploid cultivated oat (Avena sativa L. sensu lato) from 85 countries of the Plant Gene Resources of Canada (PGRC) collection was conducted at Saskatoon, Saskatchewan, Canada. Eight environmentally stable morphological characters (panicle type, panicle erectness, panicle density, lemma colour, dorsal awn of lemma, ligula, major infraspecific group), differentiated into 18 character states, were used to define genetically distinct morphological groups. Comparisons of oat diversity from different countries, among the major infraspecific groups and among Canadian oat cultivars registered between 1886 and 2002 were possible. The 10,105 accessions represented 118 different morphological groups. The number of accessions in each morphological group was unevenly distributed with the 13 most frequent morphological groups including 90% of the accessions. The most frequent morphological groups in the PGRC collection were identical with the most frequent types of Canadian oat cultivars. The greatest richness of diversity was found in oat from countries with temperate climates and intensive oat breeding programmes. The oat accessions comprised 8,754 accessions of common hulled oat, 183 accessions of hull-less oat and 1,168 accessions of red oat. For red oat (A. byzantina C. Koch), West Asia was richest in diversity. The USA could be considered a secondary centre of diversity for red oat and Canada a secondary centre of diversity for hull-less oat. Morphological diversity of oat cultivars released in Canada increased during the twentieth century. The morphological groups were related to formal taxonomical infraspecific classifications of A. sativa. Applications of the concept of defining morphological groups for phenotyping a large germplasm collection are demonstrated discussed.

K. Hammer and G. Laghetti, 2006. Small Agricultural Islands and Plant Genetic Resources

During a 10 year period starting in 1994, the authors conducted a systematic exploration of the cultivated crop plants on Italian islands. The results of this joint Italian-German research program are presented in this book. The book consists of two major sections. The first 128 pages present brief information on geology, geography, geomorphology, ecology, history, demography, agriculture, native and cultivated flora of 45 Italian islands. Notes on additional islands or adjacent mainland are also supplied. This part is illustrated with 146 mostly coloured photographs of characteristic landscapes, typical plants, and various impressions from agriculture and horticulture. The information was gathered during numerous germplasm collecting missions and interviews with local experts including farmers, who preserved and utilized the genetic resources. In-depth information on typical landraces, such as their folk names and special usages, are provided for several crop types. The second part of the book presents chapters summarizing the germplasm findings and extracting information on genetic erosion and historical developments. A table listing the numbers and categories of collected germplasm together with some geographical and demographic information covering 30 islands is presented. A checklist for 180 typical island crop plants is presented and the diversity status of selected taxa is discussed. The authors used 255 references, to mostly botanical contributions, showing that a vast body of literature has been inspected for related information. The appendix lists Italian folk names of the typical crop plants, synonyms for the botanical plant names used and an index of the species names occurring in this book. This book has several functions. In the foreword L. Monti (IGV) stated that ‘‘Loss of cultural identity and of local genetic resources are processes that are intimately related.’’ Both issues are addressed in this book. The authors have given an example that comprehensive diversity research in crop plants goes beyond the technical aspects of collecting, preserving and studying useful, rare or threatened crop plant diversity. By providing broad information on the ecological and socio-cultural context of the collected material, the authors show parts of the complex dynamics which result in crop genetic diversity or uniformity. Such a broad approach, based on several years of systematic exploration, is rare these days. The book counteracts the loss of cultural identity, because it creates awareness for the underlying and ongoing processes, which can easily be overlooked by the people affected by A. Diederichsen (&) Saskatoon Research Centre, Plant Gene Resources of Canada, 107, Science Place, Saskatoon, SK, Canada S7N OX2 e-mail: diederichsena@agr.gc.ca

Microsatellite variation in Avena sterilis oat germplasm

The Avena sterilis L. collection in the Plant Gene Resources of Canada (PGRC) consists of 11,235 accessions originating from 27 countries and is an invaluable source of genetic variation for genetic improvement of oats, but it has been inadequately characterized, particularly using molecular techniques. More than 35 accessions have been identified with genes for resistance to oat crown and stem rusts, but little is known about their comparative genetic diversity. This study attempted to characterize a structured sample of 369 accessions representing 26 countries and two specific groups with Puccinia coronata avenae (Pc) and Puccinia graminis avenae (Pg) resistance genes using microsatellite (SSR) markers. Screening of 230 SSR primer pairs developed from other major crop species yielded 26 informative primer pairs for this characterization. These 26 primer pairs were applied to screen all the samples and 125 detected alleles were scored for each accession. Analyses of the SSR data showed the effectiveness of the stratified sampling applied in capturing country-wise SSR variation. The frequencies of polymorphic alleles ranged from 0.01 to 0.99 and averaged 0.28. More than 90% of the SSR variation resided within accessions of a country. Accessions from Greece, Liberia, and Italy were genetically most diverse, while accessions from Egypt, Georgia, Ethiopia, Gibraltar, and Kenya were most distinct. Seven major clusters were identified, each consisting of accessions from multiple countries and specific groups, and these clusters were not well congruent with geographic origins. Accessions with Pc and Pg genes had similar levels of SSR variation, did not appear to cluster together, and were not associated with the other representative accessions. These SSR patterns are significant for understanding the progenitor species of cultivated oat, managing A. sterilis germplasm, and exploring new sources of genes for oat improvement.

Genetic diversity for agronomic, morphological and seed quality traits in Sinapis alba L. (yellow mustard)

The objective of this research was to study the amount and pattern of phenotypic diversity among 179 Sinapis alba accessions maintained in germplasm collections at Plant Gene Resources of Canada (PGRC) and the Saskatoon Research Centre of Agriculture and Agri-Food Canada (SRC-AAFC). Accessions were evaluated in five field trials at Saskatoon from 1994 to 1998. Observations were recorded on number of days to flower and to mature, plant height, 1000-seed weight, oil and protein content and selected fatty acids and glucosinolates. Analysis of variance and mean comparisons were used to characterize variation in the germplasm. There was significant variation among accessions for all traits except some minor fatty acids and glucosinolates. Principal component analysis indicated that five or six principal components provided a good summary of the data, accounting for 75–80% of the variation. In all trials, the first principal component axis separated accessions predominantly on the basis of erucic acid (C22:1) and oleic acid (C18:1), with associated C22 and C18 fatty acids. The relative importance of agronomic, morphological and other seed quality traits varied among the trials, but they were always less important than C22:1 and C18:1. Cluster analysis generated 10–13 groups of accessions in each trial except in 1997 (five clusters). Distinct clusters were identified that possessed high or low values for C22:1, C18:1, oil and protein content, maturity, plant height and seed weight. Seed colour was not used as a classification variable; however, brown-seeded accessions were grouped into one distinct cluster due to a significantly higher level of C22:1 in these accessions. This study demonstrates that the S. alba accessions maintained at PGRC and SRC-AAFC are a source of genetic diversity for breeding both condiment (high glucosinolate and C22:1 content) and vegetable (low glucosinolate and C22:1 content) oilseed yellow mustard and for conducting genetic studies. Key words: Sinapis alba, genetic diversity, cluster analysis, principal component analysis

Genetic diversity ofSinapis albagermplasm as revealed by AFLP markers

Sinapis albaL. is a major specialty crop grown as a condiment in western Canada, but little is known about its genetic diversity. The objective of this study was to assess the level and pattern of genetic diversity in a collection of 127S. albaaccessions held at Plant Gene Resources of Canada using amplified fragment length polymorphism (AFLP) markers. Five AFLP primer pairs were applied, and 134 polymorphic bands were scored for each accession. These scored bands had frequencies of occurrence ranging from 0.02 to 0.99 with an average of 0.69. More AFLP variation was found within single (79.1%) than between (20.9%)S. albaaccessions. A small degree of AFLP difference (1.7%) was observed among the accessions of various regions, while relatively large variation (9.2%) existed among the accessions of various countries. A large AFLP difference (15.6%) also existed between the yellow- and brown-seeded accessions, but only 6.2% difference was observed between the cultivar and landrace accessions. Two distinct groups ofS. albagermplasm were identified on the basis of the seed colour (yellow or brown), although a few mixtures also existed. No apparent ‘duplicated’ accessions were observed. The most diverse accessions were from Italy, Spain, France and Greece. Among the most genetically distinct accessions were SA97 from Portugal, SA89 and SA88 from France, SA83 from Russia and SA57 from Italy. These findings are significant not only for managingS. albagermplasm, but also for identifying diverse germplasm that can be used by plant breeders to improveS. albaseed yield and quality parameters.

Seed colour, seed weight and seed oil content in Linum usitatissimum accessions held by Plant Gene Resources of Canada

AbstractThe purpose of this study was to investigate variation of and relationships among seed colour, seed weight and seed oil content in cultivated flax (Linum usitatissimum L. ssp. usitatissimum). Seed from 2934 flax genebank accessions recently grown at Saskatoon, SK, Canada, originating from 72 countries was used to describe the variation of the seed characters. The dominant seed colour of the accessions was medium brown (2730 accessions, 93.0%), followed by yellow (126 accessions, 4.3%). Based on single observations for all accessions, the overall mean and standard deviation was 5.95 ± 1.22 mg/seed for seed weight and 38.3 ± 1.74% for oil concentration. Within three infraspecific groups of flax, seed weight, oil concentration and oil amount per seed increased in the following order: fibre flax (convar. elongatum), intermediate flax (convar. usitatissimum), large‐seeded flax (convar. mediterraneum). The world collection exceeded the range of variation of seed weight and oil concentration found in 52 North American cultivars. There was a weak, positive association of higher oil concentration with higher seed weight (r2 = 0.32; P < 0.001). Yellow‐seeded flax had a higher seed weight (6.31 vs. 5.92 mg/seed) and oil concentration (39.4% vs. 38.3%) than brown‐seeded flax. There was a tendency for yellow seed colour to be associated with higher oil concentration in all seed weight classes. The results suggested that indirect selection for increased seed oil concentration in flax is possible by selection for higher seed weight and yellow seed colour.

Preservation Methods for Jerusalem Artichoke Cultivars

Preservation methods were evaluated for jerusalem artichokes (Helianthus tuberosus L.) to facilitate the back-up of field collections. In vitro plant cultures were established from field-harvested tubers for nine jerusalem artichoke cultivars obtained from the Plant Gene Resources of Canada, Saskatoon Research Center, Saskatoon, Canada. Most cultivars could be maintained at 5 °C or under 25 °C growth room conditions for at least 6 months. Excised shoot tips from in vitro cultures were cryopreserved using plant vitrification solution 2 (PVS2; 15% w/v ethylene glycol, 15% w/v dimethyl sulfoxide, 30% w/v glycerol, and 13.7% w/v sucrose in half strength media salts) as a cryoprotectant. PVS2 exposures of 15 or 30 min at 0 °C resulted in an average regrowth of 34% across five jerusalem artichoke cultivars after liquid nitrogen exposure. Jerusalem artichokes can be successfully maintained using both reduced temperature and cryopreservation approaches.

Variation of Mucilage in Flax Seed and Its Relationship with Other Seed Characters

A four‐location trial in western Canada with 16 North American flax (Linum usitatissimum L.) cultivars was conducted in 2001 and 2002 to investigate the genotypic and environmental influences on mucilage in the flax seed coat. The viscosity of a water extract from intact flax seed was used as quantitative descriptor of the seed‐coat mucilage (mucilage indicator value, MIV). Thousand‐seed weight (TSW) and oil content in the seed were also observed. The MIV in the 16 cultivars ranged from 90.6 to 246.1 centistokes (cSt) mL g−1, TSW ranged from 5.21 to 6.91 g, and oil content ranged from 447 to 491 g kg−1 Significant differences were found among the cultivars for all characters. A screening of 1689 recently regenerated accessions from 61 countries of the Plant Gene Resources of Canada (PGRC) flax collection showed MIVs ranging from 22.1 to 343.4 cSt mL g−1 The ranges for TSW and oil content were 3.53 to 11.50 g and 314 to 457 g kg−1, respectively. The group displaying the highest MIV included registered North American cultivars. There was no association of MIV with geographic origin, TSW, or seed oil content. Recent North American linseed cultivars varied considerably for MIVs, and breeding for this trait without impact on seed oil content or TSW should be possible.

Phenotypic and Molecular (RAPD) Differentiation of Four Infraspecific Groups of Cultivated Flax (Linum usitatissimum L. subsp. usitatissimum)

Based on agro-botanical characterization data, 3101 accessions of cultivated flax (Linum usitatissimum L. subsp. usitatissimum) from the flax collection held by Plant Gene Resources of Canada (PGRC) were grouped into four infraspecific groups according to the classification proposed by Kulpa and Danert (1962) . The objective of this study was to investigate phenotypic and RAPD variation within and among the four groups to better understand phenotypic and genotypic differentiation within the genepool of cultivated flax. The results of the phenotypic characterization of characters defining the convarieties (capsule dehiscence, plant height, technical stem length and 1000 seed weight) and of other quantitative (petal width, oil content in seeds) and qualitative (RAPD, petal colour, anther colour, petal longitudinal folding and margin folding, ciliation of capsule septa, seed colour) are presented using descriptive statistics. The most frequent convariety in the PGRC genebank was intermediate flax (convar. usitatissimum; 80.7 %), followed by fibre flax (convar. elongatum Vav. et Ell. in Wulff; 13.4%), large-seeded flax (convar. mediterraneum [Vav. ex Ell.] Kulpa et Danert; 5.6%) and dehiscent flax (convar. crepitans [Boenningh.] Kulpa et Danert; 0.3%). Analyses of RAPD data and two qualitative characters (longitudinal and marginal folding of petals) did not show marked differences among the proposed convarieties. However, differences among the convarieties in quantitative traits defining them (plant height, technical stem length and seed size) were considerable. Patterns of variation among the convarieties for other quantitative characters (petal width and seed oil content), as well as the frequencies of character expressions of four qualitative characters (petal colour, anther colour, ciliation of capsule septa and seed colour) were significantly associated with the four proposed convarieties, underlining the phenotypic and genotypic validity of this grouping. The patterns of geographic distribution of the convarieties and important characters showed that certain convarieties dominate in some areas of origin. The infraspecific classification and the presented characterization data increase the transparency of genetic diversity available in cultivated flax and in particular in the PGRC flax collection.