Common Buckwheat Cultivars Research Articles

Analysis of Genetic Diversity and Population Structure of Buckwheat (Fagopyrum esculentum Moench) Landraces of Korea Using SSR Markers

Buckwheat (Fagopyrum esculentum Moench), one of the minor crops grown in Korea belonging to the Polygonaceae family, is an annual crop widely cultivated in Asia, Europe, and America and has a character of outcrossing and self-incompatibility. The objective of this study was to analyze the genetic variability, phylogenetic relationships and population structure of buckwheat landraces of Korea using SSR markers. Ten microsatellite markers have been detected from a total of 79 alleles among the 179 buckwheat accessions were collected from Korea. The number of allele per marker locus (N A ) ranged from 2 (GB-FE-001, GB-FE-043 and GB-FE-055) to 31 (GB-FE-035) with an average of 7.9 alleles. GB-FE-035 was the most polymorphic with the highest PIC value 0.93. Major allele frequencies (M AF ) for the 10 polymorphic loci varied from 0.12 to 0.97 with a mean allele frequency of 0.57. The expected heterozygosity (H E ) values ranged from 0.05 to 0.94 with an average of 0.53. The observed heterozygosity (H O ) ranged from 0.06 to 0.92 with an average of 0.42. The overall polymorphic information contents (PIC) values ranged from 0.05 to 0.93 with an average of 0.48. The landrace accessions of buckwheat used in the present study were not distinctly grouped according to geographic distribution. The study concludes that the results revealed genetic differentiation was low according to the geographic region because of outcrossing and self-incompatibility. We reported that our analyses on the genetic diversity of common buckwheat cultivars of Korea were performed by using of microsatellite markers.

Intraspecific responses of Fagopyrum esculentum to enhanced ultraviolet B radiation

The effects of supplemental UV-B radiation on crop growth, morphology, reproduction and physiology were studied in three cultivars of Fagopyrum esculentum Moench (buckwheat) originating from high elevation (Qinghai-Tibet plateau) and lower altitudes (The Sichuan Basin). Our results showed that common buckwheat was sensitive to UV-B stress. Plant growth, development, and reproduction were inhibited by elevated UV-B radiation. Plant lipid oxidation and polyphenol oxidase (PPO) activity increased with increasing UV-B radiation, along with the concentration of phenylpropanoid compounds, superoxide dismutase (SOD) activity and ascorbic acid (Asa) concentration were also enhanced at the lowest level of supplemental UV-B radiation but decreased at the higher level of enhanced UV-B. While, a cultivar originating from elevated locations had lower dry matter accumulation and was more tolerant to UV-B radiation than cultivars originating from lower elevations. The effects on leaf thickness and increased antioxidant capacity could be linked with the improved performance of cultivar originating from high elevation when exposed to enhanced UV-B radiation. We conclude that UV-B tolerance should be considered prior to introducing or breeding common buckwheat cultivars from lowland cultivation to regions at high elevation such as the Qinghai-Tibet plateau.

Evaluation of the performance of flours from cross- and self-pollinating Canadian common buckwheat ( Fagopyrum esculentum Moench) cultivars in soba noodles

Two Canadian cross-pollinating common buckwheat ( Fagopyrum esculentum Moench) varieties, Koban and Koto, and two self-pollinating lines, BR01 and BR06, were dehulled and roller milled on a pilot mill to produce three distinct milled products, white flour, dark flour and whole groat flour. The white flours contained mostly starch (79.2–87.2%), whereas the dark flours were rich in proteins (37.1–38.7%), dietary fibre (15.2–22.0%), ash (5.49–5.99%), and fagopyritols (1420–2220 mg/100 g). The buckwheat flours were blended with wheat flour (Canada Western Red Spring straight grade flour) at 60:40 ratios and evaluated for soba noodle properties. Significant differences in milling properties, and in raw noodle colour and texture were detected among cultivars, although the impact of flour type on noodle properties was far greater. The self-pollinating lines exhibited comparable milling and soba noodle properties to Koban. Koto exhibited slightly higher white flour yield and generally firmer noodle texture compared to the other lines. White flours produced the brightest noodles, followed by whole groat and dark flours. Dark flours yielded the thickest cooked noodles with the largest maximum cutting stress and greatest resistance to compression. Noodles prepared with white flour offered the best chewiness, springiness and recovery parameters. Soba noodles prepared with dark flours contained considerably higher amounts of minerals, proteins, dietary fibre, and fagopyritols than noodles prepared with white flour.

Effects of water deficit and selenium on common buckwheat (Fagopyrum esculentum Moench.) plants

Two cultivars of common buckwheat (Fagopyrum esculentum), Pyra and Siva, were exposed to three treatments: water deficit (WD), foliar spraying by selenium (as Na2SeO4) (Se), and the combination of both. In WD-plants the stomatal conductance (g s) was significantly lower, while WD+Se-plants of Siva had significantly higher g s. None of the treatments resulted in significant differences of potential photochemical efficiency of photosystem 2 (PS2). A significantly higher actual photochemical efficiency of PS2 was obtained in Siva WD-plants and in Pyra Se-and WD-plants which was possibly due to improvement of plant water management during treatment. A significant interaction was observed between the effects of WD and Se on respiratory potential in Pyra. WD, Se, and the WD+Se combination resulted in shorter Pyra and Siva plants, with a reduced number of nodes. WD slightly negatively affected the yield per plant. The yield was highest in plants exposed to Se only. In Siva the number of seeds was triple while the average seed mass remained unchanged.

Genetic diversity among Japanese indigenous common buckwheat (Fagopyrum esculentum) cultivars as determined from amplified fragment length polymorphism and simple sequence repeat markers and quantitative agronomic traits

We assessed the genetic diversity in Japanese indigenous common buckwheat (Fagopyrum esculentum) cultivars using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers and investigated the relationships between the genetic diversity and agronomic traits. The average expected intracultivar hetero zygosity was 0.303 for AFLP and 0.819 for SSR. The differentiations among agroecotypes, among cultivars within an agroecotype, and among cultivars were small (0.002, 0.024, and 0.026 for SSR and 0.013, 0.013, and 0.026 for AFLP, respectively) but statistically significant from zero except for the SSR differentiation among agroecotypes. In principal coordinates analysis, cultivars within the same agroecotype tended to cluster, indicating that agroecotypes well reflected the genetic relationships among cultivars. In AFLP, the differentiation among the agroecotypes was more distinct than in SSR, and genetic distance showed a moderate correlation with the difference in quantitative traits, indicating that AFLP can resolve the relationships among cultivars with better resolution than SSR. By contrast, SSR may be more sensitive to demographic changes. Four of the five SSR markers showed a significant positive correlation (Kendall's tau = 0.382-0.607) between allelic richness and variation in flowering timing, indicating that cumulative bottleneck events have occurred during the population history, with a decline in the variation of photosensitivity of flowering.

Variation in Seed Shape and Husk Color in Japanese Native Cultivars of Common Buckwheat (Fagopyrum esculentum Moench)

The variation in seed shape and husk color was investigated in 56 Japanese native cultivars of common buckwheat. Analysis of variance revealed highly significant differences among the cultivars in seed shape characteristics and husk colors. The 1000-seed weight (1000-SW) ranged widely, from 20.4 to 39.0 g, among the cultivars. The cultivars collected from the Kanto region of the mainland had a large length and width of seed and heavy 1000-SW. On the other hand, the cultivars from the Chugoku and Shikoku regions of Japan had a small length and width of seed. The length and width of seeds showed a high positive correlation. The cultivars with a high 1000-SW showed a slight difference between length and width of seed and were typically the triangular type in seed shape. The length/width ratio (L/W) depended on the width rather than the length of seed, though both were negatively correlated with the L/W. Highly positive correlations were found among the L*, a* and b* husk color value. The L* showed a highly positive correlation with growth duration, and the husk color of the cultivars became more deep black as growth duration decreased. The husk color of the cultivars from the Kyushu region (long growth duration) was grayish brown, but that of the cultivars from Nagano Pref. (the shortest growth duration) was characterized as typically deep black. The cultivars collected at lower latitude regions tended to have a lighter color of husk than those from higher latitude regions. The cultivars from the Tohoku region showed a smaller variation for seed size characteristics and 1000-SW, and the cultivars from the Kyushu region showed a smaller variation for husk color.

Identification of AFLP makers linked to non-seed shattering locus (sht1) in buckwheat and conversion to STS markers for marker-assisted selection.

Shattering habit in buckwheat has two forms: brittle pedicel and weak pedicel. Brittle pedicel is observed in wild buckwheat, but not in cultivated buckwheat. Brittle pedicel in buckwheat is produced by two complementary, dominant genes, Sht1 and Sht2. The sht1 locus is linked to the S locus; almost all common buckwheat cultivars possess the allele sht1. To detect molecular makers linked to the sht1 locus, we used amplified fragment-length polymorphism (AFLP) analysis in combination with bulked segregant analysis of segregating progeny of a cross between a non-brittle common buckwheat and a brittle self-compatible buckwheat line. We screened 312 primer combinations and constructed a linkage map around the sht1 locus by using 102 F2 plants. Five AFLP markers were linked to the sht1 locus. Two of these, e54m58/610 and e55m46/320, cosegregated with the sht1 locus without recombination. The two AFLP markers were converted to STS markers according to the sequence of the AFLPs. The STS markers are useful for marker-assisted selection of non-brittle pedicel plants and provides a stepping-stone for map-based cloning and characterization of the gene encoding non-brittle pedicel.

Technological quality of common buckwheat (Fagopyrum esculentum Moench.)

Seven cultivars of common buckwheat were tested in field trials under two levels of nitrogen fertilisation on two experimental sites during 1998–2000. The aim of the experiments was to evaluate the influence of cultivar, nutrition and year on main technological quality parameters (thousand achenes weight, volume weight, proportion of fractions on sieves 4.5 and 4 mm, proportion of husks and yield of groats). The differences were observed between buckwheat cultivars in all observed parameters of technological value. Nitrogen fertilisation before sowing (50 kg.ha<sup>–1</sup>) did not influence any parameter. On the contrary, buckwheat technological value was influenced by sequence weather (particularly rainfalls) during flowering and achenes formation periods (July). The influence of year was manifested especially on development of endosperm and husks of achenes. Better growing conditions on experimental site Uhříněves caused lower values of volume weight, lower proportion of pericarp (husks) and considerably higher proportion of fraction over 4.5 mm.

Variation of Plant Types in Japanese Native Cultivars of Common Buckwheat (Fagopyrum esculentum Moench).

要旨 : 普通ソバ日本在来品種56系統を熊本県九州沖縄農業研究センター圃場で8月下旬に播種,栽培し,主茎長,分枝長,分枝数,花房数,節数などの主茎と分枝に関する14形質を調査した.主茎長,分枝数など11形質間には互いに正の相関がみられ,これらの形質は生育日数との間にも正の相関がみられた.分枝長/主茎長比が大きくなるに伴い,分枝着生角度は増加する傾向がみられた.15形質をもとに主成分分析を行った結果,累積寄与率は第2主成分までで75%であった.第1主成分は主茎長,分枝長,主茎節数などの植物体の大きさをあらわす形質との相関が高かった.第1主成分と生育日数との間には,密接な直線関係がみられ,在来品種の植物体の大きさは生育日数に対応していると考えられた.第2主成分は分枝着生角度,分枝長/主茎長比と正の相関がみられ,節間長,初花節位,主茎長と負の相関がみられたことから,第2主成分は植物体の形をあらわしていると考えられた.第2主成分得点の分布幅は第1主成分得点の増加に伴って大きくなり,在来品種の植物体の大きさに伴って草型の変異幅が大きくなった.西日本の在来品種は草型に関して多様性を持っていると考えられた.

Fagopyritols, D-chiro-inositol, and other soluble carbohydrates in buckwheat seed milling fractions.

Fagopyritols are mono-, di-, and trigalactosyl derivatives of D-chiro-inositol that accumulate in seeds of common buckwheat (Fagopyrum esculentum Moench) and may be important for seed maturation and as a dietary supplement. Fagopyritols and other soluble carbohydrates were assayed in mature groats and 11 milling fractions of common buckwheat seed. Because fagopyritols are in embryo and aleurone tissues, differences in fagopyritol concentrations reflect varying proportions of these tissues in each milling fraction. Bran milling fractions contained 6.4 g of total soluble carbohydrates per 100 g of dry weight, 55% of which was sucrose and 40% fagopyritols. Flour milling fractions had reduced fagopyritol concentration [0.7 g/100 g of dry weight total fagopyritols in the dark (Supreme) flour and 0.3 g/100 g in the light (Fancy) flours]. Fagopyritol B1 was 70% of total fagopyritols in all milling fractions. Fagopyritols were 40% of total soluble carbohydrates in groats of two cultivars of common buckwheat but 21% in groats of tartary buckwheat [Fagopyrum tataricum (L.) Gaertn.], probably a reflection of environment and genetics. A rhamnoglucoside present in tartary buckwheat was not detected in common buckwheat.

Breaking Strength of Pedicel as an Index of Grain-Shattering Habit in Autotetraploid and Diploid Buckwheat (Fagopyrum esculentum Moench.) Cultivars

The grain-shattering habit was compared among diploid and autotetraploid cultivars of common buckwheat (Fagopyrum esculentum Moench.). In the first experiment, one diploid and one autotetraploid cultivar were grown in the field, and the number of grains shed naturally by wind or rain, and the number of grains detached by threshing the plants (by dropping from 1 m height onto a concrete floor, five times) were measured to evaluate grain shattering. The number of the naturally shed grains in the field was higher in the diploid than in the autotetraploid cultivar, although the number of grains detached by threshing was not different between the two cultivars. In another set of experiments, breaking bending strength and breaking tensile strength of pedicels were measured as indices of grain-shattering habit to examine the difference in shattering among two autotetraploid and four diploid cultivars (two summer types and two autumn types). They were grown in summer and autumn seasons to examine the environmental effect on grain shattering. Both breaking strengths were about two times higher in the autotetraploid cultivars than in the diploid cultivars. The breaking strength was well correlated with the diameter of pedicels. The values of grain-shattering resistance traits obtained in the autumn cropping season were higher than those obtained in the summer cropping season.

Differences in the Progression of Succesive Flowering between Summer and Autumn Ecotype Cultivars in Common Buckwheat (Fagopyrum esculentum Moench).

普通ソバ品種しなの夏そば(夏型品種)および宮崎在来(秋型品種)を夏栽培および秋栽培して, 花房および小花房内の花の位置別に開花調査し, 開花の進行状況の差異を明らかにした.しなの夏そばの夏栽培および宮崎在来の秋栽培では開花数が個体あたり600～850個で, 開花期間が約1ヶ月であったのに対して, 宮崎在来の夏栽培では開花数が2600個以上で, 開花期間が役4ヶ月にもなった.また, しなの夏そばの秋栽培では開花数199個で, 開花期間は半月にしかならなかった.宮崎在来の夏栽培では開花数が多いにもかかわらず, 結実率が極端に低かったために, 一方, しなの夏そばの秋栽培は結実率が高かったものの, 開花数が少なかったために, いずれも痩果数が少なくなった.開花期間の長かった宮崎在来夏栽培では開花期間中3回の開花数の極大期であり, 秋栽培とほぼ同時期に開花終了した.その開花後期には(1)新しい花房の発生の継続, (2)開花終了花房に蕾の再発生, (3)休眠側芽の再生長が起こった.1花房内でみても, 1小花房内での開花数が多く, 上位節花房では小花房数も多いことによって, 開花数が多く, 開花期間が長かった.また, 花房間, 小花房間および小花房内の各花間の開花期間隔が長いことによって, 開花始後の開花数増加が秋栽培より緩やかであった.しなの夏そばの秋栽培では開花期間隔は夏栽培と同程度であったが, 花房数, 小花房数および小花房あたり花数が少ないことによって, 開花数が少なく, 開花期間が短くなった.

Quantitative evaluation of common buckwheat (Fagopyrum esculentum Moench) kernel shape by elliptic Fourier descriptor.

Kernel shape of 27 common buckwheat cultivars was evaluated quantitatively by image analysis using elliptic Fourier descriptors and their principal components. The relationships between the quantitative information on kernel shape and several agronomic characteristics were clarified. The closed contour of each kernel projection was extracted, and 80 elliptic Fourier coefficients were calculated for each contour. The Fourier coefficients were standardized so that they were invariant of the size, rotation, shift and chain-code starting point. Then, the principal components on the standardized Fourier coefficients were evaluated. The cumulative contribution at the fifth principal component was higher than 93%. It was found that the first, second, third and fifth principal components represented the aspect ratio of the kernel, the location of the kernel centroid, the sharpness of the two kernel tips and the roundness of the base in the kernel contour, respectively. Analysis of the variance indicated that genotypic differences in these principal components were significantly large. Because these variations of the principal components were continuous, the effect of polygenes on shape was suggested. The relationships between these principal components and agronomic traits, including flowering period, yield, 1000 seed weight and volume weight, were also investigated. It was clarified that the first principal component was closely correlated with agronomic traits such as flowerig period, 1000 seed weight and volume weight. In conclusion, it was clarified that principal component scores based on elliptic Fourier descriptors yield useful quantitative parameters for evaluating kernel shape for common buckwheat breeding.

Seed protein variation for identification of common buckwheat (Fagopyrum esculentum Moench) cultivars

Total seed proteins of 24 common buckwheat cultivars and cultivated populations within a molecular weight range of 30 to 54 kDa were analysed by SDS-PAGE. Single seed analysis of six cultivars identified a total of 18 alternative protein bands with different mobilities. Differences of individual protein band frequencies extracted from single seeds among six buckwheat cultivars varied distinctively, indicating high intravarietal polymorphism. The relation between frequencies of protein bands revealed by single seed analysis and their appearance on the bulk seed analyses was demonstrated. Regarding to band mobility rate and relative band intensity among 24 bulk samples analysed, 14 had distinctive electrophoregrams while the other 10 were ranged into four distinct groups. Analysis of endosperm and cotyledon proteins showed that proteins stored in these main seed parts are tissue specific. The observed electrophoretic polymorphism related to proteins stored in the cotyledons while there was no apparent variability with endosperm proteins.

Inter-varietal variations of rutin content in common buckwheat flour (Fagopyrum esculentum Moench.)

To improve the quality of buckwheat flour, we investigated the effect of the cropping season on the rutin content in various cultivars of common buckwheat (Fagopyrum esculentum Moench.). Thirty cultivars of buckwheat were grown under both long day conditions (the summer cropping) and short day conditions (the late summer cropping). The inter-varietal variations and the effect of the cropping season on the rutin content were examined. The rutin content was determined by high performance liquid chromatography (HPLC). Results show that the average rutin content in the late summer cropping was about half that of the summer cropping. There were wide inter-varietal variations of rutin content in the summer cropping. The differences in rutin content in the late summer cropping were less pronounced. Rutin content was closely correlated with the flowering period in summer (r=0.735***). The later flowering cultivars produced a higher content of rutin than the earlier flowering cultivars in the summer cropping. The differences in the cumulative solar radiation received in the two seasons seems to be a reasonable explanation for this increase in the rutin content of the buckwheat flour. The rutin content of early flowering cultivars, which are suitable for long day conditions, is positively correlated with yield in the summer cropping. However, the rutin content in the intermediate and late summer ecotype cultivars, which are suitable for short day conditions, shows no correlation with yield in the late-summer cropping. In conclusion, there are wide inter-varietal variations of rutin content in buckwheat flour and the rutin content increases under long day conditions.

CHEMICAL COMPOSITION AND NUTRITIVE VALUE OF BUCKWHEAT CULTIVARS FOR LABORATORY RATS

Experiments were conducted to determine the nutritive value of selected buckwheats in comparison with common buckwheat or tartary buckwheat. A 21-day, growth trial was conducted in which 42 Spraque-Dawley rats (initial weight 57 g) were randomly assigned to one of seven dietary treatments. Experimental diets contained the buckwheat cultivars, Mancan, Tempest and Tokyo, two unselected forms of common buckwheat (common and CM 169), tartary buckwheat or a casein control. Diets were formulated to supply 10% crude protein by dilution of the test protein with varying levels of a basal diet. An additional 36 rats were utilized in digestibility studies. There was little difference in chemical composition, mineral content, level of indispensable amino acids or digestibility coefficients between selected and unselected varieties of common buckwheat, while tartary buckwheat had lower levels of crude protein, lower indispensable amino acids, higher acid detergent fiber levels and lower apparent digestibility coefficients for dry matter, crude protein and energy. Weight gain and feed conversion efficiency were significantly (P < 0.05) improved for rats fed the selected varieties of buckwheat in comparison with those fed the common or tartary buckwheat. The overall results suggest that the selected cultivars of common buckwheat will support improved animal performance. Key words: Buckwheat, rats, nutritive value, digestibility