Buckwheat Populations Research Articles

The Origin of Cultivated Buckwheat in Mankang District of the Sanjiang Area of Eastern Tibet and its Diffusion to India and the Himalayan Hills

Natural populations of the wild ancestor of cultivated common buckwheat were searched and collected, starting from its discovery in1990 and finishing the collections in 2005. Among the collections, the samples Zhuka, Xihe from Mankang district of Tibet are most closely related to cultivated common buckwheat. On the other hand, cultivated populations of common buckwheat in Zhouba, Zhubalong both from Mankang district are most closely related with the wild ancestor of common buckwheat. This leads to the hypothesis on the origin of cultivated buckwheat in Mankang district in the Sanjiang area. The diffusion rout from the original birthplace to India and the Himalayan hills is proposed. Several characteristics of Indian and Himalayan common buckwheat are discussed. A main conclusion of the discussion is that the European buckwheat is not of Indian origin nor of the Himalayan origin. It probably came from the northern China through the Silk Road.

Genomic insight into the origin, domestication, dispersal, diversification and human selection of Tartary buckwheat.

Tartary buckwheat, Fagopyrum tataricum, is a pseudocereal crop with worldwide distribution and high nutritional value. However, the origin and domestication history of this crop remain to be elucidated. Here, by analyzing the population genomics of 567 accessions collected worldwide and reviewing historical documents, we find that Tartary buckwheat originated in the Himalayan region and then spread southwest possibly along with the migration of the Yi people, a minority in Southwestern China that has a long history of planting Tartary buckwheat. Along with the expansion of the Mongol Empire, Tartary buckwheat dispersed to Europe and ultimately to the rest of the world. The different natural growth environments resulted in adaptation, especially significant differences in salt tolerance between northern and southern Chinese Tartary buckwheat populations. By scanning for selective sweeps and using a genome-wide association study, we identify genes responsible for Tartary buckwheat domestication and differentiation, which we then experimentally validate. Comparative genomics and QTL analysis further shed light on the genetic foundation of the easily dehulled trait in a particular variety that was artificially selected by the Wa people, a minority group in Southwestern China known for cultivating Tartary buckwheat specifically for steaming as a staple food to prevent lysine deficiency. This study provides both comprehensive insights into the origin and domestication of, and a foundation for molecular breeding for, Tartary buckwheat.

Increasing planting density can improve the yield of Tartary buckwheat.

Planting densities and nitrogen fertilizer application rates determine the yield of crops. Tartary buckwheat is a pseudocereal crop with great health care and development values. However, little is known about application of nitrogen fertilizer and planting density on the physiological characteristics of Tartary buckwheat. This study aims to clarify the effect of planting density on the senescence and yield of Tartary buckwheat under low nitrogen conditions. A 2-year field experiment was conducted on Tartary buckwheat (Jinqiao 2) to study the effects of different planting densities (8 × 105, 10 × 105, 12 × 105, 14 × 105, and 16 × 105 plants·ha-1) on the root morphology and activity, chlorophyll and malondialdehyde (MDA) contents, antioxidant enzyme activity, photosynthetic characteristics, agronomic traits, and yield of Tartary buckwheat in the absence of nitrogen fertilizer treatment. With the increase in planting density, the root morphological indices and activities; chlorophyll a, chlorophyll b, and carotenoid contents; superoxide dismutase and peroxidase activities; net photosynthetic rate; transpiration rate; intercellular CO2 concentration and transpiration rate; main stem node, branch, and leaf numbers; grain number and weight per plant; and 1000-grain weight of Jinqiao 2 decreased continuously, whereas plant height and leaf MDA content increased continuously. The yield of Tartary buckwheat first increased and then decreased with the increase in planting density. The yield under 14 × 105 plants·ha-1 treatment increased by 68.61%, 44.82%, 11.00%, and 22.36%, respectively, relative to that under 8 × 105, 10 × 105, 12 × 105, and 16 × 105 plants·ha-1treatments. In summary, planting at an appropriately high density (14 × 105 plants·ha-1) can promote the increase in the yield of Tartary buckwheat populations under low nitrogen conditions and is recommended for use in production to achieve the high-yielding and nitrogen saving cultivation of Tartary buckwheat. This research can serve as a theoretical basis to jointly achieve the high yield and nitrogen saving of Tartary buckwheat.

Assessment on induced genetic variability and divergence in the mutagenised tartary buckwheat populations developed using gamma rays and EMS mutagenesis

For the purpose of increasing yield, induced mutagenesis was used to induce the genetic variability in Fagopyrum tataricum germplasm. Evaluation were done on the genetic diversity, trait association, and genetic divergence between the gamma rays and EMS mutated populations and one parent population. The results of the analysis of variance revealed that the observed quantitative phenotypic traits varied significantly between populations. In comparison to their parent population, the mean of the various treated populations displayed significantly superior quantitative phenotypic traits. The likelihood of yield increase by phenotypic selection in F. tartaricum was substantiated by higher h2 and GA values with high genotypic GCV. The number of inflorescence and flower per plant as well as seeds per inflorescence considered to be key attributes in screening for increased yield. The cluster analysis split the complete populations of F. tartaricum into seven distinct groups, with control population in a separate group, demonstrating the significant effectiveness of the mutagenic treatments. Taking into account the maximal involvement of the yield trait to genetic divergence among the clustered populations, it was concluded that the applied treatments resulted in a large hereditary variance for the characteristic in the mutagenised populations. Additionally, hybridization among the divergent group's members would result in a variety of segregants for crop development. In addition, induced mutations in chosen elite lines at loci affecting economically significant traits have effectively added to the diversification of the genetic base and could be surely be of great help to future mutation breeding approaches.

Genetic analysis of agronomic traits of inter-subspecific cross populations of Tartary buckwheat

To provide a good basis for breeding new varieties, 2 different Tartary buckwheat (Fagopyrum tataricum Gaertn. 2x = 16) lines belonging to different subspecies with large differences in plant height were crossed. The progeny was analyzed for the genetic pattern of each agronomic trait and correlation analysis between traits. In terms of their coefficients of variation, the node numbers on the main stem and the weights per thousand kernels were small, while the number/weight of seeds per plant was large, indicating that the former character is more stable while the latter has greater potential for improvement. The average degrees of the dominance of plant height, number of main stem nodes, and number/weight of seeds per plant were greater than 1, indicating that these traits were mainly controlled by dominant effects. The heritability of the thousand kernel weight was greater than for the other traits, indicating that this trait is suitable for single plant selection in early generations. Correlation analysis of each agronomic trait revealed that plant height was significantly and positively correlated with all other traits in the F3 population, indicating the difficulty of selecting strains with both dwarf stature and high-yield traits. Nevertheless, 13 strains with dwarf stems and high yields were screened in the F5 population. Our study shows that the thousand kernel weight can be improved by single plant selection, while other traits need to be considered together to achieve optimal selection when endeavoring to breed dwarf, high-yield Tartary buckwheat.

2S albumin g13 polypeptide, less related to Fag e 2, can be eliminated in common buckwheat (Fagopyrum esculentum Moench) seeds

2S albumin (g11, g13, g14, and g28) is an important allergen in common buckwheat (Fagopyrum esculentum). g13 is hydrophobic, rare in seeds, and may show distinct allergenicity from the others; therefore, we tried to eliminate this protein. Phylogenetic and property distance analyses indicated g13 is less related to g14 (Fag e 2) than g11/g28 is related to g14, particularly in the second domain containing the II and III α-helices. A null allele with a 531 bp insertion in the coding region was found for g13 at an allele frequency of 2 % in natural populations of common buckwheat. The g13_null allele homozygote accumulated no g13 protein. A BLAST search for the 531 bp insertion suggested the insert-like sequence resided frequently in the buckwheat genome, including the self-incompatibility responsible gene ELF3 in Fagopyrum tataricum. The g13_null insert-like sequence could, therefore, help in producing hypoallergenic cultivars, and expand the genetic diversity of buckwheat.

Evolutionary relationship between a wild ancestor of common buckwheat Fagopyrum esculentum subsp. ancestrale and a self-compatible relative F. homotropicum based on microsatellite variability

Information on the genetic variation of crop wild relatives is important for their utilization and in situ and ex situ conservation. Cultivated common buckwheat Fagopyrum esculentum subsp. esculentum has two wild relatives, wild common buckwheat (F. esculentum subsp. ancestrale) and F. homotropicum. We evaluated the genetic diversity within and among natural populations of these species using microsatellite markers. Genetic diversity values averaged over loci within wild common buckwheat populations ranged from 0.503 to 0.668, which were higher than those of F. homotropicum that ranged from 0.138 to 0.333. F. homotropicum showed a high level of genetic differentiation among populations (FST = 0.606), whereas the corresponding estimate for wild common buckwheat was much lower (FST = 0.272). These contrasts between species are largely consistent with differences in their mating system; common buckwheat exhibits heterostylous self-incompatibility and F. homotropicum exhibits homostylous self-compatibility. A phylogenetic analysis and Bayesian clustering revealed that local populations of wild common buckwheat were divided into northern and southern groups. F. homotropicum was not monophyletic as some populations were closely related to the southern group of wild common buckwheat. These results strongly suggest that the self-compatible species F. homotropicum diverged multiple times from wild common buckwheat. Our study indicates that both wild relatives of cultivated common buckwheat retain a substantial level of genetic diversity and are potentially useful genetic resources for the genetic improvement of cultivated common buckwheat.

Rapid genotyping with DNA micro-arrays for high-density linkage mapping and QTL mapping in common buckwheat (Fagopyrum esculentum Moench).

For genetic studies and genomics-assisted breeding, particularly of minor crops, a genotyping system that does not require a priori genomic information is preferable. Here, we demonstrated the potential of a novel array-based genotyping system for the rapid construction of high-density linkage map and quantitative trait loci (QTL) mapping. By using the system, we successfully constructed an accurate, high-density linkage map for common buckwheat (Fagopyrum esculentum Moench); the map was composed of 756 loci and included 8,884 markers. The number of linkage groups converged to eight, which is the basic number of chromosomes in common buckwheat. The sizes of the linkage groups of the P1 and P2 maps were 773.8 and 800.4 cM, respectively. The average interval between adjacent loci was 2.13 cM. The linkage map constructed here will be useful for the analysis of other common buckwheat populations. We also performed QTL mapping for main stem length and detected four QTL. It took 37 days to process 178 samples from DNA extraction to genotyping, indicating the system enables genotyping of genome-wide markers for a few hundred buckwheat plants before the plants mature. The novel system will be useful for genomics-assisted breeding in minor crops without a priori genomic information.

Isozyme diversity and genetic structure of buckwheat populations

Abstract Genetic diversity of 35 Fagopyrum populations belonging to thirteen taxa was studied using isozyme variation at 16 loci for nine enzyme systems ( ADH , α-AMY , EST , GDH , GOT , IDH , MDH , PGM , and POD ). The mean number of alleles per locus ( A p ) showed little variation, ranging from 1.38 to 1.71. The mean percentage of polymorphic ( P ) of the thirteen taxa was high, ranging from 68.75% to 93.75. The mean expected heterozygosity ( H e ) ranged from 0.21 to 0.37. Obvious grouping of populations according to taxonomic species was found in the cluster analysis, confirmed that the thirteen taxa studied were independent, with a clear boundary. Based on the dendrogram, the phylogenic relationship of Fagopyrum species are in agreement with the achene size were found, and it was inferred that southwestern China should be the original center of cultivated buckwheat.

Principal component analysis of intraspecific responses of tartary buckwheat to UV-B radiation under field conditions

Fifteen populations of tartary buckwheat ( Fagopyrum tataricum Gaertn.) occurring in habitats with different natural UV-B levels were sampled, and the plants were exposed to enhanced UV-B radiation under field conditions simulating 25% depletion of the stratospheric ozone layer. The experimental design was a 2 × 15 factorial, with two levels of UV-B radiation (ambient and enhanced UV-B radiation) and plants from 15 populations. The responses of plants in growth, morphology, productivity and in the composition of photosynthetic pigments were measured. The results demonstrated that there were significant differences among populations in responses to UV-B radiation: some populations exhibited a positive effect while others were negatively affected. The UV-B effects on plant traits were correlated with the constitutive values. A principal component analysis (PCA) was used to evaluate the overall sensitivity of responses to UV-B radiation. Our results suggest that the sensitivity of plants to UV-B radiation is not only associated with the ambient UV-B level in natural habitats but also with the relative growth rate and other factors.

Close genetic relationship between cultivated and natural populations of common buckwheat in the Sanjiang area is not due to recent gene flow between them-An analysis using microsatellite markers

Natural populations of wild common buckwheat have been found growing adjacent to cultivated populations of common buckwheat. Gene flow between the cultivated and natural populations would be expected in such cases. To evaluate the amount of gene flow, two sets composed of a cultivated buckwheat population and an adjacent natural population of wild common buckwheat were chosen, one from Yanjing village in the Sanjiang area, which is presumed to be the original birthplace of common buckwheat, and one from Jinhe village, Yanyuan district of Sichuan province in China. The genotypes of 45 individuals from each population were examined at eight microsatellite marker loci to estimate the magnitude of gene flow between the cultivated and wild common buckwheat populations. The Bayesian method with a Markov chain Monte Carlo approach estimated that the magnitude of gene flow between the populations in the Sanjiang area at 0.002-0.008 was not significantly different from that found in Yanyuan district at 0.002-0.008. The gene flow between cultivated populations was higher, usually at 0.002-0.044 (exceptionally high at 0.255 between cultivated populations of Yanjing and Jinhe), than that found between a cultivated population and a natural population (0.002-0.008) or between two natural populations (0.002-0.003). Therefore, the genetic similarity found between the cultivated populations and natural populations observed in the Sanjiang area (Konishi et al., 2005) was not due to recent gene flow between them. This in turn suggests that the close genetic relationship found in the Sanjiang area may be due to the common ancestry of the natural populations and cultivated common buckwheat.

Development and Characterization of Microsatellite Markers for Common Buckwheat

So far, only five microsatellite markers have been developed in common buckwheat (Fagopyrum esculentum). The purpose of the present study was to develop a larger number of microsatellite markers in common buckwheat. By sequencing 2785 clones from the libraries, which were enriched for (CT)n and (GT)n repeats using magnetic particles, it was shown that 1483 clones contained microsatellites, of which 352 had unique sequences. Primer pairs were designed for 237 of the microsatellite loci, of which 180 primer pairs each amplified PCR products. Fifty-four primer pairs that each amplified a clear PCR product of the expected size were evaluated for their ability to detect variations in common buckwheat populations and to be utilized in seven related Fagopyrum species. Forty-eight (88.9%) out of the 54 microsatellite markers tested were found to be highly variable (the average number of alleles was 12.2 and the average polymorphism information content (PIC) was 0.79) in a population of cultivated buckwheat. This PIC value was comparatively large when compared with the average values for microsatellite markers reported for other crops. A high rate of successful amplification of common buckwheat microsatellite markers was observed in closely related species; in particular all the 54 loci were successfully amplified in the wild ancestor of cultivated common buckwheat. The microsatellite markers developed in the present study should contribute to the promotion of molecular breeding in common buckwheat.

Glyphosate-resistant spring wheat production system effects on weed communities

Glyphosate-resistant (GR) crops are produced over large areas in North America. A study was conducted at six western Canada research sites to determine seed date and tillage system effects on weed populations in GR spring wheat and canola cropping systems from 2000 to 2003. Four-year wheat–canola–wheat–pea rotations were devised with varying levels of GR crops in the rotation. Weed populations were determined at pre– and post–in-crop herbicide application intervals in 2000 and 2003. Early seeding led to higher and more variable in-crop wild oat and wild buckwheat populations. High frequencies of in-crop glyphosate wheat in the rotation usually improved weed management and reduced weed density and variability. Canonical discriminant analysis (CDA) across all locations revealed that by 2003, green foxtail, redroot pigweed, sowthistle spp., wild buckwheat, and wild oat, all associated with the rotation lacking in-crop glyphosate. Similar CDA analyses for individual locations indicated specific weeds were associated with 3 yr of in-crop glyphosate (Canada thistle at Brandon, henbit at Lacombe, and volunteer wheat, volunteer canola, and round-leaved mallow at Lethbridge). However, only henbit at Lacombe and volunteer wheat at Lethbridge occurred at significant densities. Although excellent weed control was attained in rotations containing a high frequency of GR crops, the merits of more integrated approaches to weed management and crop production should also be considered. Overall, rotations including GR spring wheat did not significantly increase short-term weed management risks in conventional tillage or low soil-disturbance direct-seeding systems.

ASSESSING SCRUB BUCKWHEAT POPULATION VIABILITY IN RELATION TO FIRE USING MULTIPLE MODELING TECHNIQUES

We used a variety of modeling approaches to assess the effects of fire on the demography and population viability of scrub buckwheat (Eriogonum longifoliumvar. gna- phalifolium), a threatened herb endemic to periodically burned xeric uplands in central Florida, USA. We compared the management implications of different approaches. Using demographic data from ten years including five fires, we constructed Lefkovitch matrix models of scrub buckwheat populations in unburned habitats for populations experiencing a burn and for populations one year after burning. Deterministic analysis of the unburned matrices predicted relatively stable populations in unburned habitats using optimistic fertility estimates ( l5 1.002, 95% CI 0.975-1.033), but almost certain decline given pessimistic fertility estimates ( l5 0.981, 0.962-1.003). Burned populations are always predicted to increase (CI on l. 1.08). Numerical calculations of single-year growth rates based on the expected stable stage distribution of an unburned population yielded positive, but lower, growth rates. The l's calculated for periodically burned populations had confidence intervals entirely above 1 for fire return intervals shorter than 20 yr (optimistic) or 5 yr (pessimistic). Stochastic simulations yielded highly uncertain estimates of the probability of quasi-extinction over 250 yr, with only fire return intervals shorter than 20 yr (optimistic) or 5 yr (pessimistic) yielding quasi- extinction confidence intervals entirely below 1. Population growth rates in partially burned areas increased linearly with the proportion burned. The results of these density-independent simulations remained virtually unchanged (maximum difference of 5.2%) by introducing plausible population ceilings. Regression and stasis transitions had the highest elasticities for unburned populations, while fecundity elasticities were relatively greater for burn years. Transient elasticity analysis on total population size of simulated single-year post-fire growth and on the population vector five years in the future showed broadly similar patterns to standard elasticities, although the standard analysis assigned higher elasticity values to tran- sitions contributing to future reproductive potential. Fire management is important to en- couraging viable populations. Our analysis suggests minimum fire return intervals of 20 yr (optimistic) or 5 yr (pessimistic). These fire return intervals are consistent with those often used in the sandhill and oak-hickory scrub habitats of scrub buckwheat.

Buckwheat composition, chemistry, and processing

Publisher Summary Buckwheat is a traditional food widely utilized throughout the world. Buckwheat contains some nutritionally beneficial components at high levels and may have many characteristics as a functional food. This chapter describes various characteristics of buckwheat as an important and traditional food. Buckwheat belongs to the Polygonaceae family and is taxonomically distant from the Gramineae family to which cereals such as rice, wheat, and maize belong. However, buckwheat seed has chemical and utilization characteristics similar to cereal grains, and thus is usually classified as a cereal. It is often alternatively classified as a pseudocereal. Buckwheat is mainly classified into three types with respect to harvesting season: summer type, autumn type, and middle type. This classification may be due to susceptibility to the day length. Buckwheat breeding has been extensively discussed. Chloroplast DNA analysis in buckwheat species has shown that the DNA of Fagopyrum esculentum is phylogenetically distant from those of Fagopyrum tataricum and Fagopyrum cymosum. Evaluation of genetic variability among common buckwheat populations has shown that the dendrogram separates accessions into a European group and an Asian group.

Phylogenetic relationships among natural populations of perennial buckwheat, Fagopyrum cymosum Meisn., revealed by allozyme variation

Twenty natural populations of F. cymosum, an insect-pollinated allogamous wild species of Fagopyrum, were investigated for their chromosome number and allozyme variation at 10 Ioci encoding 8 enzymes. Diploid populations were obtained in Sichuan, Yunnan and Tibet in China, whereas tetraploid populations were obtained in Tibet, the Himalayan hills, Thailand and southern China. Both diploid and tetraploid populations maintained a large amount of allozyme variation. The average heterozygosity, He, ranged from 0.045 to 0.389 (0.213 on average). Tetraploid populations showed higher He values than diploid populations. Natural populations of F. cymosum were locally well differentiated (GST = 0.322), probably due to reproductive isolation between the two ploidy levels and to distribution over wide areas from southern China to the Himalayan hills. The phylogenetic tree constructed by the neighbor-joining method based on allozyme variation clarified two distinct groups of diploid populations, the Sichuan and Yunnan groups. As for the tetraploid populations, polyploidization occurred twice independently, once in Yunnan and once in eastern Tibet. Tetraploid F. cymosum diffused to warmer areas such as southern Yunnan and Thailand as well as to cooler areas of Tibet and the high Himalayan hills and became the most widely distributed of the Fagopyrum species.

Evaluation of genetic variability among common buckwheat ( Fagopyrum esculentum Moench) populations by RAPD markers

Genetic variability among 80 accessions of common buckwheat was evaluated using random decamer primers in polymerase chain reaction (PCR) amplification of bulked DNA samples. Thirteen primers, previously chosen on the basis of the number and intensity of the fragments they produced, were used for amplification and yielded a total of 141 bands, of which 77 were polymorphic. An NTSYS-pc computer program was further employed for data analysis using a simple matching coefficient of similarity as a base for dendrogram construction via the UPGMA method. A moderate level of polymorphism and relatively close relationships among the studied common buckwheat populations were observed. The dendrogram separated accessions into European and Asian groups, with a number of additional clusters and some inconsistant populations from both regions. Clusters corresponded reasonably well to the geographical origins of examined populations, with some unexpected but interesting exceptions. The effectiveness of RAPD analysis of bulked DNA samples for the study of genetic variability in common buckwheat was demonstrated, and this approach seems very useful for identification and phylogenetic studies.

Population genetics of cultivated common buckwheat, Fagopyrum esculentum Moench. IX. Concluding remarks on worldwide survey of allozyme variability.

By adding data on allozyme variability in 35 populations from southern and central China, I completed a worldwide survey of allozyme variability in common buckwheat. The following remarks were born out from the survey. (1) At all loci, allele frequency does not vary so much among the populations from a wide range of Asian countries. (2) Most of the evolutionary events which might occur during the spread of buckwheat cultivation are the losses of variant alleles by random drift. (3) Drastic changes of gene frequency have been observed only in marginal populations, in Kumaun, Garwhal hills and Kashmir in India and in southern Europe. (4) Cultivated buckwheat has more genetic variability than the natural populations of the wild ancestor. Large population size and complete panmixis of a population and enough migration between populations may be responsible for observation (1) and may also have led to the accumulation of variant alleles in cultivated populations, i.e. observation (4). Random drift, such as founder effect, took place only in marginal populations, accounting for observations (2) and (3). Buckwheat provides an example that contradicts Vavilov's assertion; it says that the center of genetic diversity of a cultivated plant is the place of its origin. Buckwheat is apparently monocentric, but the pattern of variation suggests domestication over a wide area, instead of progressive decline in diversity from the center of origin to the periphery. The structure of buckwheat populations and their mating system are mainly responsible for this unexpected result.

Population genetics of cultivated common buckheat, Fagopyrum esculentum Moench. VII. Allozyme variability in Japan, Korea, and China.

Allozyme variability at 19 loci affecting 12 enzymes were analyzed electrophoretically in 24 Japanese, 3 Korean, and 16 Chinese populations of common buckwheat. Most of the populations were polymorphic at 8 loci, Adh, Dia-2, Got-2, Mdh-1, Mdh-3, 6-Pgdh-1, Pgm-2, and Sdh-1. The percentage of polymorphic loci was 31.6-42.1% and the average heterozygosity was in the range of 0.110-0.138. The level of variability was almost the same as that found in Nepal and India, and was slightly higher than the average of other outbreeding plant species. The allelic frequencies did not vary much among the populations studied, although the Chinese populations had slightly more genetic variability than the Japanese and Korean populations. The present results together with those for the Indian and Nepali populations (Ohnishi and Nishimoto, 1988) led to the following conclusions. The allelic frequencies at the polymorphic loci did not vary much among Asian populations extending from Nepal to Japan; geographical differentiation of allozyme frequencies, due mostly to the loss of alleles, has occurred only at the margins of the distribution, such as in the Kumaun and Garwhal hills and in Kashmir in India. This rather unexpected uniformity of allelic frequencies seems to be due to large population size, panmixis within populations, and gene flow between populations, conforming to the theoretical models of Maruyama (1971) and Kimura and Maruyama (1971). Buckwheat does not have a strict center of genetic diversity, but the highest within-population variability was found in the region from southern China to Nepal. Based on the observed minor differences in allozyme frequencies between populations, possible processes of the spreading of buckwheat cultivation in Asia are discussed.

Population genetics of cultivated common buckwheat, Fagopyrum esculentum Moench. V. Further studies on allozyme variability in the Indian and Nepali Himalaya.

Electrophoretic analyses of 19 loci affecting 12 enzymes in 17 Nepali and 11 Indian populations of common buckwheat were conducted by horizontal starch gel electrophoresis. Most of the populations were polymorphic at the loci Adh, Dia-2, Got-2, Mdh-1, Mdh-3, Pgm-2, 6-Pgdh-1 and Sdh-1 and some populations were also polymorphic at the Got-1 and Gdh loci. The populations from Nepal and West Bengal maintained slightly more variability than the average of other outcrossing annual plant species. The percentage of polymorphic loci was 39.5% and the average heterozygosity was 0.133. No distinct local differentiation was found among these populations. They had similar genetic constitutions with the populations from southern China. However, distinct allelic frequencies at some loce were observed in Almora and Rishikesh, both in Uttar Pradesh, India. The Kashmirian populations had less genetic variability and they were quite different from the others. They had lost the variant alleles at the loci Adh, Dia-2, 6-Pgdh-1 and Pgm-2, probably during the spread of cultivation. The processes that might have led to the prsent geographical pattern of allozyme variability are discussed.