Fagopyrum esculentum and F. tataricum

Current Advances in Buckwheat Research (1995) : 357 - 364
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Variation of Seed Proteins in the World Cultivars of
Fagopyrum esculentum and F. tataricum
Yutaka Hirata*, Koichiro Ushijima* and Ryo Ohsawa**
* Faculty of Agriculture, Tokyo University of Agriculture & Technology, Fuchu, Tokyo,
Japan
** Hokuriku Agricultural Experiment Station, Ojiya, Niigata, Japan
Introduction
Important buckwheat includes two species and these two species diverse into several thousands
of cultivars in the world, such as South East Asia, Europe, Russia and North America. Those
cultivars include wide variations in yield, protein and rutin contents, photoresponse and so on.
Common buckwheat is strongly heterozygous and the criterion "cultivar" is not accompalished
because of strong allogamous plant which is regulated by heterostyly self-incompatibility.
Recently allergenic alubumins were widely known and partial characterizations were analysed.
However, to improve the qualities and quantities ofbuckwheat we must make clear the spectra
ofvariations in important agricultural characteristics such as proteins, rutin content with ordinal
characteristics. For that purpose, it is necessary to know world-wide variations. Firstly we tried
to survey the variations in seed storage proteins. In parallel geographycal variations and
declines were also studied.
Materials and Methods
Material cultivars used were 104 common buckwheat cultivars and 7 tartary buckwheat
cultivars from the collections by Hokuriku Agricultural Experiment Station (Ojiya, Niigata,
Japan). Typical seeds are shown in Fig. 1.
We analysed buckwheat globulin subunits by SOS-PAGE (sodium dodesyl sulfate­
polyacrylamide gel electrophoresis) and those acidic subunits by alkaline-urea PAGE.
Ten seeds of each buckwheat cultivar were crashed and ground. Globulins were extracted
from 5 mg seed powder in 80 III 0.1 M phosphate buffer (pH 7.4) containing 0.4 M NaCI, 0.1 M
2-mercaptoethanol and 10% SOS. 20 III of the extracted supernatant after centrifuge (15,000
rpm for 20min.) was served for (mini) slab gel (10%) electrophoresis (10 rnA CC for 4hrs in
electrode buffer; 3 g Tris-14.4 g Glycine (pH 8.3) containing 10% SDS per 100 ml). In case of
alkaline-urea SOS PAGE, globulin proteins were extracted in 0.05 M Tris-HCI (pH 6.8)

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containing 2.5% SDS, 0.1 % 2-mercaptoethanol and 8 M urea. For separation by gel
electrophoresis 10% gel includes 6 M urea was used. Low bis acrylamige gel system (Acryl
amide: Bis acryl amide = 30 : 0.001) was applied to seperate low molecular proteins if
necessary.
In this paper we focusted on common buckwheat proteins because of too small number of
F. tartaricum cultivars.
Results
Fundamental separation patterns oftotal globulin subunits and acidic subunits were respetively
shown in Fig. I and Fig. 2. Qualitative variations were clear between F. esculentum and
tataricum. However, qualitative variations were rarely found in common buckwheat.
Quantitative variations were very frequent in common buckwheat. Ralative production ratios
between two near-subunits were adopted for detection ofvariations.
Relative production of globulin subunits G1 to G8 were surveyd (Fig. 2). However, clear
geographic clines were not found for each relative production ratio between two near-bands so
far. However, four cultivars or strains, Bednja (Yugoslavia), 92-41 strain (Niigata),
Toyamazairai (lwate) and Kankei No.3 (Kanto) which have G7

Fig. 2a. Variation of globulin subunits. Left four are common buckwheat cultivars, right four
tartary buckwheat culrtivars. Arrowheads indicate species - specific subunits of variated
subunits.
Fig. 2b. Schematic explanation ofelectrophoretic separation pattern ofglobulin subunits. Upper
is tartary buckwheat, lower common buckwheat.
FT
FE
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Japan, all subunit compositions were in same declines, AI>A2, A2

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From the results with proteins, three acidic subunit separation patterns were classified into
Japanese and North American type, European type and Chinese type. The first group is
reasonable to include the same group, because Japanese type is cultivated in Canada and USA
for export to Japan. From the view point of that, A3, A4 and A5 would be adequate indicators
to classify between European and Japanese types.
Discussion
In this experiment qualitative variations were not clearly found. This is the reason that genes
for protein subunits are heterozygous in one cultivar or strain because of strong allogamy and
self-weakness in common buckwheat. So, the defferent productivity between two near-subunits
may be source of variation in the subnints in case of common buckwheat. Further survey in
each plant and the progenies by using clear markers is necessary. Of course, tartary buckwheat
is relative easy to survey variations due to self-pollinated plant.
By using total globulin subunits and acidic subunits there were several distictive cultivars
such as AlA3 and G7