Breeding buckwheat for nutritional quality

Buckwheat OMICS: present status and future prospects

Buckwheat (Fagopyrum spp.) is an underutilized resilient crop of North Western Himalayas belonging to the family Polygonaceae and is a source of essential nutrients and therapeutics. Common Buckwheat and Tatary Buckwheat are the two main cultivated species used as food. It is the only grain crop possessing rutin, an important metabolite with high nutraceutical potential. Due to its inherent tolerance to various biotic and abiotic stresses and a short life cycle, Buckwheat has been proposed as a model crop plant. Nutritional security is one of the major concerns, breeding for a nutrient-dense crop such as Buckwheat will provide a sustainable solution. Efforts toward improving Buckwheat for nutrition and yield are limited due to the lack of available: genetic resources, genomics, transcriptomics and metabolomics. In order to harness the agricultural importance of Buckwheat, an integrated breeding and OMICS platforms needs to be established that can pave the way for a better understanding of crop biology and developing commercial varieties. This, coupled with the availability of the genome sequences of both Buckwheat species in the public domain, should facilitate the identification of alleles/QTLs and candidate genes. There is a need to further our understanding of the molecular basis of the genetic regulation that controls various economically important traits. The present review focuses on: the food and nutritional importance of Buckwheat, its various omics resources, utilization of omics approaches in understanding Buckwheat biology and, finally, how an integrated platform of breeding and omics will help in developing commercially high yielding nutrient rich cultivars in Buckwheat.

Multi-omics identification of a key glycosyl hydrolase gene FtGH1 involved in rutin hydrolysis in Tartary buckwheat (Fagopyrum tataricum)

Rutin, a flavonoid rich in buckwheat, is important for human health and plant resistance to external stresses. The hydrolysis of rutin to quercetin underlies the bitter taste of Tartary buckwheat. In order to identify rutin hydrolysis genes, a 200 genotypes mini-core Tartary buckwheat germplasm resource was re-sequenced with 30-fold coverage depth. By combining the content of the intermediate metabolites of rutin metabolism with genome resequencing data, metabolite genome-wide association analyses (GWAS) eventually identified a glycosyl hydrolase gene FtGH1, which could hydrolyse rutin to quercetin. This function was validated both in Tartary buckwheat overexpression hairy roots and in vitro enzyme activity assays. Mutation of the two key active sites, which were determined by molecular docking and experimentally verified via overexpression in hairy roots and transient expression in tobacco leaves, exhibited abnormal subcellular localization, suggesting functional changes. Sequence analysis revealed that mutation of the FtGH1 promoter in accessions of two haplotypes might be necessary for enzymatic activity. Co-expression analysis and GWAS revealed that FtbHLH165 not only repressed FtGH1 expression, but also increased seed length. This work reveals a potential mechanism behind rutin metabolism, which should provide both theoretical support in the study of flavonoid metabolism and in the molecular breeding of Tartary buckwheat.

Accumulation of the bitter substance quercetin mediated by the overexpression of a novel seed-specific gene FtRDE2 in Tartary buckwheat

Tartary buckwheat (Fagopyrum tataricum) is frequently employed as a resource to develop health foods, owing to its abundant flavonoids such as rutin. However, the consumption of Tartary buckwheat (TB) is limited in food products due to the strong bitterness induced by the hydrolysis of rutin into quercetin. This transformation is facilitated by the degrading enzyme (RDE). While multiple RDE isoenzymes exist in TB, the superior coding gene of FtRDEs has not been fully explored, which hinders the breeding of TB varieties with minimal bitterness. Here, we found that FtRDE2 is the most abundant enzyme in RDE crude extracts, and its corresponding gene is specifically expressed in TB seeds. Results showed that FtRDE2 has strong rutin hydrolysis activity. Overexpression of FtRDE2 not only significantly promoted rutin hydrolysis and quercetin accumulation but also dramatically upregulated genes involved in the early phase of flavonoid synthesis (FtPAL1、FtC4H1、Ft4CL1, FtCHI1) and anthocyanin metabolism (FtDFR1). These findings elucidate the role of FtRDE2, emphasizing it as an endogenous factor contributing to the bitterness in TB and its involvement in the metabolic regulatory network. Moreover, correlation analysis revealed a positive relationship between the catalytic activity of RDE extracts and the expression level of FtRDE2 during seed germination. In summary, our results suggest that FtRDE2 can serve as a promising candidate for the molecular breeding of a TB variety with minimal bitterness.

Variations in chemical composition of common buckwheat (Fagopyrum esculentum Moench) as a result of different environmental conditions

BACKGROUND

Common buckwheat (Fagopyrum esculentum Moench) is a pseudo cereal that is gaining interest in the world. The chemical profile of common buckwheat determines its high nutritional and health-promoting value. The accumulation of these valuable ingredients depends on many factors, such as: variety, location of cultivation and related weather and agrotechnical conditions. Due to the growing interest in common buckwheat as a natural plant material for food production, it is important to know the factors affecting the quantitative and qualitative composition of its grains. The aim of the research was to determine the effect of the genotype (G), environment (E) and G × E interaction on the content of nutrients (protein, starch, ash, lipids) and bioactive components [dietary fiber (DF), total phenolic content (TPC)] in the common buckwheat grains. The study covered four cultivars grown in three locations for three consecutive vegetation seasons (2016/2017, 2017/2018, 2018/2019).

RESULTS

Based on the obtained results, a significant influence of the environment and G × E interaction on the content of the studied parameters was found. The greatest impact on the diversity of the content of nutrients had environmental conditions, which in the case of protein and ash determined these features in more than 80%, and in the case of starch, 70%. With regard to bioactive compounds, the greatest influence of the environment was observed for the amount of TPC (78%), lignin (51%) and the DF complex (56%).

CONCLUSION

The obtained results are useful for breeders working on expanding the pool of common buckwheat genotypes, stable in changing environmental conditions. © 2023 Society of Chemical Industry.

FlbZIP12 gene enhances drought tolerance via modulating flavonoid biosynthesis in Fagopyrum leptopodum

Karst lands provide a poor substrate to support plant growth, as they are low in nutrients and water content. Common buckwheat (Fagopyrum esculentum) is becoming a popular crop for its gluten-free grains and their high levels of phenolic compounds, but buckwheat yields are affected by high water requirements during grain filling. Here, we describe a wild population of drought-tolerant Fagopyrum leptopodum and its potential for enhancing drought tolerance in cultivated buckwheat. We determined that the expression of a gene encoding a Basic leucine zipper (bZIP) transcription factor, FlbZIP12, from F. leptopodum is induced by abiotic stresses, including treatment with the phytohormone abscisic acid, salt, and polyethylene glycol. In addition, we show that overexpressing FlbZIP12 in Tartary buckwheat (Fagopyrum tataricum) root hairs promoted drought tolerance by increasing the activities of the enzymes superoxide dismutase and catalase, decreasing malondialdehyde content, and upregulating the expression of stress-related genes. Notably, FlbZIP12 overexpression induced the expression of key genes involved in flavonoid biosynthesis. We also determined that FlbZIP12 interacts with protein kinases from the FlSnRK2 family in vitro and in vivo. Taken together, our results provide a theoretical basis for improving drought tolerance in buckwheat via modulating the expression of FlbZIP12 and flavonoid contents.

Comparative and population genomics of buckwheat species reveal key determinants of flavor and fertility

Common buckwheat (Fagopyrum esculentum) is an ancient crop with a world-wide distribution. Due to its excellent nutritional quality and high economic and ecological value, common buckwheat is becoming increasingly important throughout the world. The availability of a high-quality reference genome sequence and population genomic data will accelerate the breeding of common buckwheat, but the high heterozygosity due to the outcrossing nature has greatly hindered the genome assembly. Here we report the assembly of a chromosome-scale high-quality reference genome of F. esculentum var. homotropicum, a homozygous self-pollinating variant of common buckwheat. Comparative genomics revealed that two cultivated buckwheat species, common buckwheat (F. esculentum) and Tartary buckwheat (F. tataricum), underwent metabolomic divergence and ecotype differentiation. The expansion of several gene families in common buckwheat, including FhFAR genes, is associated with its wider distribution than Tartary buckwheat. Copy number variation of genes involved in the metabolism of flavonoids is associated with the difference of rutin content between common and Tartary buckwheat. Furthermore, we present a comprehensive atlas of genomic variation based on whole-genome resequencing of 572 accessions of common buckwheat. Population and evolutionary genomics reveal genetic variation associated with environmental adaptability and floral development between Chinese and non-Chinese cultivated groups. Genome-wide association analyses of multi-year agronomic traits with the content of flavonoids revealed that Fh05G014970 is a potential major regulator of flowering period, a key agronomic trait controlling the yield of outcrossing crops, and that Fh06G015130 is a crucial gene underlying flavor-associated flavonoids. Intriguingly, we found that the gene translocation and sequence variation of FhS-ELF3 contribute to the homomorphic self-compatibility of common buckwheat. Collectively, our results elucidate the genetic basis of speciation, ecological adaptation, fertility, and unique flavor of common buckwheat, and provide new resources for future genomics-assisted breeding of this economically important crop.

Buckwheat: an underutilized crop with attractive sensory qualities and health benefits

The pseudocereal buckwheat is one of the ancient domesticated crops. The aim of the present review was to outline the potential of buckwheat as an agricultural crop and brings studies on buckwheat into a new larger perspective combining current knowledge in agricultural history and practice, nutritional and sensory properties, as well as possible benefits to human health. Historically, buckwheat was an appreciated crop because of its short growth period, moderate requirements for growth conditions, and high adaptability to adverse environments. Nowadays, interest in buckwheat-based food has increased because of its nutritional composition and many beneficial properties for human health. Buckwheat is a rich course of proteins, dietary fibers, vitamins, minerals, and bioactive compounds, including flavonoids. Moreover, it contains no gluten and can be used in the production of gluten-free foods for individuals diagnosed with celiac disease, non-celiac gluten sensitivity, or wheat protein allergies. Buckwheat is traditionally used in the production of various foods and can be successfully incorporated into various new food formulations with positive effects on their nutritional value and attractive sensory properties. Further research is needed to optimize buckwheat-based food development and understand the mechanism of the health effects of buckwheat consumption on human well-being.

Genome sequencing reveals the genetic architecture of heterostyly and domestication history of common buckwheat

Common buckwheat, Fagopyrum esculentum, is an orphan crop domesticated in southwest China that exhibits heterostylous self-incompatibility. Here we present chromosome-scale assemblies of a self-compatible F. esculentum accession and a self-compatible wild relative, Fagopyrum homotropicum, together with the resequencing of 104 wild and cultivated F. esculentum accessions. Using these genomic data, we report the roles of transposable elements and whole-genome duplications in the evolution of Fagopyrum. In addition, we show that (1) the breakdown of heterostyly occurs through the disruption of a hemizygous gene jointly regulating the style length and female compatibility and (2) southeast Tibet was involved in common buckwheat domestication. Moreover, we obtained mutants conferring the waxy phenotype for the first time in buckwheat. These findings demonstrate the utility of our F. esculentum assembly as a reference genome and promise to accelerate buckwheat research and breeding.

Exploring the potential of cold plasma treatment followed by zinc-priming for biofortification of buckwheat sprouts

Increasing the concentration of an element in edible produce (i.e., biofortification) can mitigate the element deficiency in humans. Sprouts are small but popular part of healthy diets providing vitamins and essential elements throughout the year. Element composition of sprouts can easily be amended, e.g., by soaking the grains in element-rich solution before germination (grain-priming). In addition, pre-treatment of grains to improve element translocation from the solution into the grain may further enhance the element concentration in the sprout. Cold plasma technique could provide such solution, as it increases wettability and water uptake of grains. Grains of common buckwheat (Fogopyrum esculentum Moench) were pre-treated/ untreated with cold plasma and soaked in ZnCl₂ solution/pure water. Germination tests, α-amylase activity, grain hydrophilic properties and water uptake were assessed. Element composition of grain tissues and of sprouts was assessed by micro-particle-induced-X-ray emission and X-ray fluorescence spectroscopy, respectively. Grain-priming increased Zn concentration in shoots of common buckwheat sprouts more than five-times, namely from 79 to 423 mg Zn kg^-1 dry weight. Cold plasma treatment increased grain wettability and water uptake into the grain. However, cold plasma pre-treatment followed by grain-priming with ZnCl₂ did not increase Zn concentration in different grain tissues or in the sprouts more than the priming alone, but rather decreased the Zn concentration in sprout shoots (average ± standard error: 216 ± 6.13 and 174 ± 7.57 mg Zn kg^-1 dry weight, respectively). When the fresh weight portion of whole sprouts (i.e., of roots and shoots) was considered, comparable average requirements of Zn, namely 24.5 % and 35 % for adult men and women would be satisfied by consuming cold plasma pre-treated and not pre-treated grains. Potential advantages of cold plasma pre-treatment need to be tested further, mainly to optimize the duration of soaking required to produce Zn-enriched sprouts.

Development and chromosomal characterization of interspecific hybrids between common buckwheat (Fagopyrum esculentum) and a related perennial species (F. cymosum)

Common buckwheat (Fagopyrum esculentum) is an annual self-incompatible plant that is widely grown. The genus Fagopyrum comprises more than 20 species, including F. cymosum, a perennial that, unlike common buckwheat, is highly resistant to excess water. In this study, we developed interspecific hybrids between F. esculentum and F. cymosum via embryo rescue, to improve undesirable traits of common buckwheat, such as low tolerance to excess water. The interspecific hybrids were confirmed by genomic in situ hybridization (GISH). We also developed DNA markers to confirm the identity of the hybrids and if genes derived from each genome were inherited by the next generation. Observations of pollen indicated that the interspecific hybrids were essentially sterile. Unpaired chromosomes and abnormal segregation during meiosis were likely responsible for the pollen sterility of the hybrids. These findings could facilitate buckwheat breeding to produce lines that can withstand harsh environments with wild or related species in the genus Fagopyrum.

Tartary Buckwheat Grain as a Source of Bioactive Compounds in Husked Groats

Tartary buckwheat (Fagopyrum tataricum Gaertn.) originates in mountain regions of Western China, and is cultivated in China, Bhutan, Northern India, Nepal, and Central Europe. The content of flavonoids in Tartary buckwheat grain and groats is much higher than in common buckwheat (Fagopyrum esculentum Moench), and depends on ecological conditions, such as UV-B radiation. Buckwheat intake has preventative effects in chronic diseases, such as cardiovascular diseases, diabetes, and obesity, due to its content of bioactive substances. The main bioactive compounds in Tartary buckwheat groats are flavonoids (rutin and quercetin). There are differences in the bioactivities of buckwheat groats obtained using different husking technologies, based on husking raw or pretreated grain. Husking hydrothermally pretreated grain is among the traditional ways of consuming buckwheat in Europe and some parts of China and Japan. During hydrothermal and other processing of Tartary buckwheat grain, a part of rutin is transformed to quercetin, the degradation product of rutin. By adjusting the humidity of materials and the processing temperature, it is possible to regulate the degree of conversion of rutin to quercetin. Rutin is degraded to quercetin in Tartary buckwheat grain due to the enzyme rutinosidase. The high-temperature treatment of wet Tartary buckwheat grain is able to prevent the transformation of rutin to quercetin.

QTL mapping and candidate gene analysis for yield and grain weight/size in Tartary buckwheat

BACKGROUND

Grain weight/size influences not only grain yield (GY) but also nutritional and appearance quality and consumer preference in Tartary buckwheat. The identification of quantitative trait loci (QTLs)/genes for grain weight/size is an important objective of Tartary buckwheat genetic research and breeding programs.

RESULTS

Herein, we mapped the QTLs for GY, 1000-grain weight (TGW), grain length (GL), grain width (GW) and grain length-width ratio (L/W) in four environments using 221 recombinant inbred lines (XJ-RILs) derived from a cross of 'Xiaomiqiao × Jinqiaomai 2'. In total, 32 QTLs, including 7 for GY, 5 for TGW, 6 for GL, 11 for GW and 3 for L/W, were detected and distributed in 24 genomic regions. Two QTL clusters, qClu-1-3 and qClu-1-5, located on chromosome Ft1, were revealed to harbour 7 stable major QTLs for GY (qGY1.2), TGW (qTGW1.2), GL (qGL1.1 and qGL1.4), GW (qGW1.7 and qGW1.10) and L/W (qL/W1.2) repeatedly detected in three and above environments. A total of 59 homologues of 27 known plant grain weight/size genes were found within the physical intervals of qClu-1-3 and qClu-1-5. Six homologues, FtBRI1, FtAGB1, FtTGW6, FtMADS1, FtMKK4 and FtANT, were identified with both non-synonymous SNP/InDel variations and significantly differential expression levels between the two parents, which may play important roles in Tatary buckwheat grain weight/size control and were chosen as core candidate genes for further investigation.

CONCLUSIONS

Two stable major QTL clusters related to grain weight/size and six potential key candidate genes were identified by homology comparison, SNP/InDel variations and qRT‒qPCR analysis between the two parents. Our research provides valuable information for improving grain weight/size and yield in Tartary buckwheat breeding.

Principal Components and Cluster Analysis of Trace Elements in Buckwheat Flour

Essential trace elements are required at very low quantities in the human body but are essential for various physiological functions. Each trace element has a specific role and a lack of these elements can easily cause a threat to health and can be potentially fatal. In this study, inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used to determine the content of trace metal elements Ca, Fe, Cu, Mg, Zn, Se, Mo, Mn, and Cd in buckwheat flour. The content and distribution characteristics of trace metal elements were investigated using principal component and cluster analysis. The principal component analysis yielded a four-factor model that explained 73.64% of the test data; the cumulative contribution of the variance of the 1st and 2nd principal factors amounted to 44.41% and showed that Cu, Mg, Mo, and Cd are the characteristic elements of buckwheat flour. The cluster analysis divided the 28 buckwheat samples into two groups, to some extent, reflecting the genuineness of buckwheat flour. Buckwheat flour is rich in essential trace metal elements and can be used as a source of dietary nutrients for Mg and Mo.

Rewiring of the seed metabolome during Tartary buckwheat domestication

Crop domestication usually leads to the narrowing genetic diversity. However, human selection mainly focuses on visible traits, such as yield and plant morphology, with most metabolic changes being invisible to the naked eye. Buckwheat accumulates abundant bioactive substances, making it a dual-purpose crop with excellent nutritional and medical value. Therefore, examining the wiring of these invisible metabolites during domestication is of major importance. The comprehensive profiling of 200 Tartary buckwheat accessions exhibits 540 metabolites modified as a consequence of human selection. Metabolic genome-wide association study illustrates 384 mGWAS signals for 336 metabolites are under selection. Further analysis showed that an R2R3-MYB transcription factor FtMYB43 positively regulates the synthesis of procyanidin. Glycoside hydrolase gene FtSAGH1 is characterized as responsible for the release of active salicylic acid, the precursor of aspirin and indispensably in plant defence. UDP-glucosyltransferase gene FtUGT74L2 is characterized as involved in the glycosylation of emodin, a major medicinal component specific in Polygonaceae. The lower expression of FtSAGH1 and FtUGT74L2 were associated with the reduction of salicylic acid and soluble EmG owing to domestication. This first large-scale metabolome profiling in Tartary buckwheat will facilitate genetic improvement of medicinal properties and disease resistance in Tartary buckwheat.

The Lipid-Soluble Bioactive Substances of Fagopyrum esculentum Varieties under Different Tillage and Nitrogen Fertilisation

Yield and grain composition play an important role in food production. The aim of this study was to determine the content of phytosterols, squalene, and tocopherols in four varieties of common buckwheat grains: Kora, Panda, Smuga, and Korona depending on the tillage and nitrogen doses employed. The grains were cultivated at the Experimental Station of the State Research Institute of Soil Science and Plant Cultivation in Osiny, Poland, with plow tillage, without plow tillage cultivation, and with nitrogen fertilizers (0, 50, and 100 kg N₂ ha^-1). Gas chromatography with a mass spectrometer was used to assess all the parameters studied. The cultivation methods did not affect the levels of phytosterols, tocopherols, and squalene, but the highest levels of phytosterols were seen in the Kora variety with 50 kg N₂ ha^-1 (ranging from 1198 μg to 1800 μg·g^-1 of sample weight); therefore, the variety was the best source of phytosterols investigated.

Molecular Shield for Protection of Buckwheat Plants from UV-B Radiation

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) and common buckwheat (Fagopyrum esculentum Moench) are adapted to growing in harsh conditions of high altitudes. Ultraviolet radiation at high altitudes strongly impacts plant growth and development. Under the influence of ultraviolet radiation, protecting substances are synthesized in plants. The synthesis of UV-B defense metabolites is genetically conditioned, and their quantity depends on the intensity of the ultraviolet radiation to which the plants and plant parts are exposed. These substances include flavonoids, and especially rutin. Other substances with aromatic rings of six carbon atoms have a similar function, including fagopyrin, the metabolite specific for buckwheat. Defensive substances are formed in the leaves and flowers of common and Tartary buckwheat, up to about the same concentration in both species. In comparison, the concentration of rutin in the grain of Tartary buckwheat is much higher than in common buckwheat. Flavonoids also have other functions in plants so that they can protect them from pests and diseases. After crushing the grains, rutin is exposed to contact with the molecules of rutin-degrading enzymes. In an environment with the necessary humidity, rutin is turned into bitter quercetin under the action of rutin-degrading enzymes. This bitterness has a deterrent effect against pests. Moreover, flavonoids have important functions in human nutrition to prevent several chronic diseases, including obesity, cardiovascular diseases, gallstone formation, and hypertension.

Genetic basis of maturity time is independent from that of flowering time and contributes to ecotype differentiation in common buckwheat (Fagopyrum esculentum Moench)

BACKGROUND

Common buckwheat is considered a quantitative short-day plant and is classified into the autumn (highly photoperiod sensitive), summer (weakly photoperiod sensitive), and intermediate ecotype. Understanding ecotype differentiation is essential for adaptive expansion and maximizing yield. The genetic analysis for ecotype has focused on photoperiod-dependent flowering time, whereas post-flowering traits such as seed set and maturity time might also regulate ecotype differentiation.

RESULTS

A field experiment revealed that ecotype differentiation is mainly defined by the timing of seed set and maturation, whereas flowering time is less relevant. Thus, we focused on maturity time as a trait that defines the ecotype. To detect QTLs for maturity time, we developed two F₂ populations derived from early × late-maturing accessions and intermediate × late-maturing accessions. Using genotyping by random amplicon sequencing-direct analysis, we generated a high-density linkage map. QTL analysis detected two major QTLs for maturity time, one in each F₂ population. We also detected QTLs for flowering time at loci different from maturity time QTLs, which suggests that different genetic mechanisms regulate flowering and maturity. Association analysis showed that both QTLs for maturity time were significantly associated with variations in the trait across years.

CONCLUSIONS

Maturity time appeared to be more suitable for explaining ecotype differentiation than flowering time, and different genetic mechanisms would regulate the timing of flowering and maturation. The QTLs and QTL-linked markers for maturity time detected here may be useful to extend the cultivation area and to fine-tune the growth period to maximize yield in buckwheat.

JA-induced FtBPM3 accumulation promotes FtERF-EAR3 degradation and rutin biosynthesis in Tartary buckwheat

Buckwheat accumulates abundant flavonoids, which exhibit excellent health-promoting value. Flavonoids biosynthesis is mediated by a variety of phytohormones, among which jasmonates (JAs) induce numerous transcription factors, taking part in regulation of flavonoids biosynthesis genes. However, some transcriptional repressors appeared also induced by JAs. How these transcriptional repressors coordinately participate in JA signaling remains unclear. Here, we found that the disruption of the GCC-box in FtF3H promoter was associated with flavonoids accumulation in Tartary buckwheat. Further, our study illustrated that the nucleus-localized FtERF-EAR3 could inhibit FtF3H expression and flavonoids biosynthesis through binding the GCC-box in the promoter of FtF3H. The JA induced FtERF-EAR3 gene expression while facilitating FtERF-EAR3 protein degradation via the FtBPM3-dependent 26S proteasome pathway. Overall, these results illustrate a precise modulation mechanism of JA-responsive transcription suppressor participating in flavonoid biosynthesis, and will further help to improve the efficiency of flavonoids biosynthesis in Tartary buckwheat.

Comparison of Heat and Drought Stress Responses among Twelve Tartary Buckwheat (Fagopyrum tataricum) Varieties

The use of orphan crops could mitigate the effects of climate change and improve the quality of food security. We compared the effects of drought, high temperature, and their combination in 12 varieties of Tartary buckwheat (Fagopyrum tataricum). Plants were grown at 21/19 °C or 28/26 °C under well-watered and water-stressed conditions. Plants were more discriminated according to environmental conditions than variety, with the exception of Islek that was smaller and produced fewer leaves, inflorescences, and seeds than the other varieties. The combination of high temperature and water stress had a stronger negative impact than each stress applied separately. The temperature increase stimulated leaf and flower production while water stress decreased plant height. Leaf area decreased with both temperature and water stress. High temperature hastened the seed initiation but negatively affected seed development such that almost all seeds aborted at 28 °C. At 21 °C, water stress significantly decreased the seed production per plant. At the physiological level, water stress increased the chlorophyll content and temperature increased the transpiration rate under well-watered conditions. High temperature also increased the polyphenol and flavonoid concentrations, mainly in the inflorescences. Altogether, our results showed that water stress and temperature increase in particular negatively affected seed production in F. tataricum.

Decontamination and Germination of Buckwheat Grains upon Treatment with Oxygen Plasma Glow and Afterglow

Buckwheat is an alternative crop known for its many beneficial effects on our health. Fungi are an important cause of plant diseases and food spoilage, often posing a threat to humans and animals. This study reports the effects of low-pressure cold plasma treatment on decontamination and germination of common (CB) and Tartary buckwheat (TB) grains. Both plasma glow and afterglow were applied. The glow treatment was more effective in decontamination: initial contamination was reduced to less than 30% in CB and 10% in TB. Fungal diversity was also affected as only a few genera persisted after the glow treatment; however, it also significantly reduced or even ceased the germination capacity of both buckwheat species. Detailed plasma characterisation by optical spectroscopy revealed extensive etching of outer layers as well as cotyledons. Afterglow treatment resulted in a lower reduction of initial fungal contamination (up to 30% in CB and up to 50% in TB) and had less impact on fungal diversity but did not drastically affect germination: 60–75% of grains still germinated even after few minutes of treatment. The vacuum conditions alone did not affect the fungal population or the germination despite an extensive release of water.

Buckwheat Milling Waste Effects on Root Morphology and Mycorrhization of Silver Fir Seedlings Inoculated with Black Summer Truffle (Tuber aestivum Vittad.)

Large amounts of buckwheat waste are generated annually by the industry and are used in several different ways. To date, there has been little research regarding its suitability as a medium for growing seedlings in nurseries. The aim of this study was therefore to analyze the suitability of common and Tartary buckwheat wastes (brans and husks) as media used for raising seedlings. A pot experiment with five different treatments was carried out, in which silver fir root parameters were analyzed and compared 6 and 12 months after summer truffle-spore inoculation. A significantly higher concentration of the antioxidant rutin was confirmed in Tartary buckwheat bran compared to other buckwheat waste used. We also confirmed a significantly positive effect of added Tartary buckwheat husks on specific root length, root tip density, and specific root tip density compared to added common buckwheat husks or Tartary buckwheat bran, for which a significantly negative effect on branching density was confirmed. A significantly negative effect of added buckwheat husks and Tartary buckwheat bran was confirmed for summer truffle mycorrhization level.

Neuroimmunomodulatory Properties of Flavonoids and Derivates: A Potential Action as Adjuvants for the Treatment of Glioblastoma

Glioblastomas (GBMs) are tumors that have a high ability to migrate, invade and proliferate in the healthy tissue, what greatly impairs their treatment. These characteristics are associated with the complex microenvironment, formed by the perivascular niche, which is also composed of several stromal cells including astrocytes, microglia, fibroblasts, pericytes and endothelial cells, supporting tumor progression. Further microglia and macrophages associated with GBMs infiltrate the tumor. These innate immune cells are meant to participate in tumor surveillance and eradication, but they become compromised by GBM cells and exploited in the process. In this review we discuss the context of the GBM microenvironment together with the actions of flavonoids, which have attracted scientific attention due to their pharmacological properties as possible anti-tumor agents. Flavonoids act on a variety of signaling pathways, counteracting the invasion process. Luteolin and rutin inhibit NFκB activation, reducing IL-6 production. Fisetin promotes tumor apoptosis, while inhibiting ADAM expression, reducing invasion. Naringenin reduces tumor invasion by down-regulating metalloproteinases expression. Apigenin and rutin induce apoptosis in C6 cells increasing TNFα, while decreasing IL-10 production, denoting a shift from the immunosuppressive Th2 to the Th1 profile. Overall, flavonoids should be further exploited for glioma therapy.

Breeding Buckwheat for Nutritional Quality in the Czech Republic

Buckwheat is a nutritionally valuable crop, an alternative to common cereals also usable in gluten-free diets. The selection of buckwheat genotypes suitable for further breeding requires the characterization and evaluation of genetic resources. The main objective of this work was to evaluate selected phenotypic and morphological traits using international buckwheat descriptors, including total phenolic content and antioxidant activity, on a unique set of 136 common buckwheat accessions grown in 2019-2020 under Czech Republic conditions. In addition, UHPLC-ESI- MS/MS was used to analyze a wide spectrum of 20 phenolic compounds in buckwheat seeds, including four flavanols, three phenolic acids, seven flavonols, four flavones, and two flavanones. Significant differences among years and genotypes were observed for morphological traits (plant height and 1000-seed weight) and antioxidant activity, as well as levels of observed chemical compounds. Antioxidant activity, crude protein content, plant height and rutin content were characterized by higher mean values in 2020 than in 2019 and vice versa for total polyphenol content and 1000-seed weight. Crude protein content was the most stable across years, while total polyphenol content and rutin content varied greatly from year to year. The most abundant phenolic compounds were rutin, hyperoside, epicatechin, catechin, vitexin, isovitexin, orientin and isoorientin. Protein content was negatively correlated with plant height, catechin and epicatechin content. On the other hand, AA and TPC were positively correlated with rutin, hyperoside and chlorogenic acid. Five accessions showed high stability of the evaluated traits under changing conditions within both years of observation. These materials can be used in breeding programmes aimed at improving buckwheat genotypes with emphasis on quality traits.

Changes in Agricultural Performance of Common Buckwheat Induced by Seed Treatment with Cold Plasma and Electromagnetic Field

The aim of this study was to determine the effects of pre-sowing seed treatment with cold plasma (CP) and an electromagnetic field (EMF) on the agricultural performance of two cultivars of common buckwheat (Fagopyrum esculentum Moench)—‘VB Vokiai’ and ‘VB Nojai’. For this, the effects of CP and EMF on seed germination, plant growth in the field, photosynthetic efficiency, biomass production, seed yield, and the amount of secondary metabolites and minerals in the harvested seeds were estimated. Although the percentage of seedlings that emerged under field conditions decreased by 11–20%, seed treatments strongly improved buckwheat growth and yield. Irrespective of differences in the dynamics of changes in the growth and photosynthetic activity between the two cultivars, the weight of seeds collected per plant for both cultivars was significantly higher (up to 70–97%) compared to the control. The biochemical composition of the harvested seeds (Fe, Zn, quercetin content) was also altered by seed treatments. Thus, pre-sowing treatment of buckwheat seeds with CP and EMF substantially stimulated plant growth in the field, increased biomass production, seed yield and nutritional quality. The results obtained strongly support the idea that plant seed treatment with physical stressors has great potential for use in agriculture.

Comparison of Plant Morphology, Yield and Nutritional Quality of Fagopyrum esculentum and Fagopyrum tataricum Grown under Field Conditions in Belgium

Buckwheat is a pseudocereal with high nutritional and nutraceutical properties. Although common buckwheat (Fagopyrum esculentum) is the main cultivated species, Tartary buckwheat (Fagopyrum tataricum) is gaining interest. In this paper, we compared plant growth, yield-related parameters and seed nutritional qualities of two varieties of F. esculentum and F. tataricum under field conditions in Belgium. Fagopyrum esculentum flowered earlier, produced less nodes, less branches, less inflorescences, but more flowers per inflorescence than F. tataricum. The yield was higher in F. tataricum, while the thousand-grain weight was higher in F. esculentum. Yield ranged between 2037 kg/ha and 3667 kg/ha depending on the species and year. Regarding nutritional qualities, seeds of F. esculentum contained more proteins (15.4% vs. 12.8%) than seeds of F. tataricum although their amino acid profile was similar. Seeds of F. esculentum contained also more Mg (1.36 vs. 1.15 mg/g dry weight (DW)) and less Fe (22.9 vs. 32.6 µg/g DW) and Zn (19.6 vs. 24.5 µg/g DW) than F. tataricum. The main difference between seed nutritional quality was the concentration of flavonoids that was 60 times higher in F. tataricum than in F. esculentum. Both species grow well under Belgian conditions and showed good seed quality.

Targeted amplicon sequencing + next-generation sequencing-based bulked segregant analysis identified genetic loci associated with preharvest sprouting tolerance in common buckwheat (Fagopyrum esculentum)

BACKGROUND

Common buckwheat (2n = 2x = 16) is an outcrossing pseudocereal whose seeds contain abundant nutrients and potential antioxidants. As these beneficial compounds are damaged by preharvest sprouting (PHS) and PHS is likely to increase with global warming, it is important to find efficient ways to develop new PHS-tolerant lines. However, genetic loci and selection markers associated with PHS in buckwheat have not been reported.

RESULTS

By next-generation sequencing (NGS) of whole-genome of parental lines, we developed a genome-wide set of 300 markers. By NGS- based bulked segregant analysis (NGS-BSA), we developed 100 markers linked to PHS tolerance. To confirm the effectiveness of marker development from NGS-BSA data, we developed 100 markers linked to the self-compatibility (SC) trait from previous NGS-BSA data. Using these markers, we developed genetic maps with AmpliSeq technology, which can quickly detect polymorphisms by amplicon-based multiplex targeted NGS, and performed quantitative trait locus (QTL) analysis for PHS tolerance in combination with NGS-BSA. QTL analysis detected two major and two minor QTLs for PHS tolerance in a segregating population developed from a cross between the PHS-tolerant 'Kyukei 29' and the self-compatible susceptible 'Kyukei SC7'. We found different major and minor QTLs in other segregating populations developed from the PHS-tolerant lines 'Kyukei 28' and 'NARO-FE-1'. Candidate markers linked to PHS developed by NGS-BSA were located near these QTL regions. We also investigated the effectiveness of markers linked to these QTLs for selection of PHS-tolerant lines among other segregating populations.

CONCLUSIONS

We efficiently developed genetic maps using a method combined with AmpliSeq technology and NGS-BSA, and detected QTLs associated with preharvest sprouting tolerance in common buckwheat. This is the first report to identify QTLs for PHS tolerance in buckwheat. Our marker development system will accelerate genetic research and breeding in common buckwheat.

Breeding Buckwheat for Increased Levels of Rutin, Quercetin and Other Bioactive Compounds with Potential Antiviral Effects

Common buckwheat (Fagopyrum esculentum Moench) and Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) are sources of many bioactive compounds, such as rutin, quercetin, emodin, fagopyrin and other (poly)phenolics. In damaged or milled grain under wet conditions, most of the rutin in common and Tartary buckwheat is degraded to quercetin by rutin-degrading enzymes (e.g., rutinosidase). From Tartary buckwheat varieties with low rutinosidase activity it is possible to prepare foods with high levels of rutin, with the preserved initial levels in the grain. The quercetin from rutin degradation in Tartary buckwheat grain is responsible in part for inhibition of α-glucosidase in the intestine, which helps to maintain normal glucose levels in the blood. Rutin and emodin have the potential for antiviral effects. Grain embryos are rich in rutin, so breeding buckwheat with the aim of producing larger embryos may be a promising strategy to increase the levels of rutin in common and Tartary buckwheat grain, and hence to improve its nutritional value.

Treasure from garden: Bioactive compounds of buckwheat

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An extensive review on diverse bioactive components of buckwheat.

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Versatile beneficial phytochemicals are abundant in buckwheat.

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Buckwheat has a wide range of pharmacological and beneficial health effects.

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Huge research scope on Fagopyrum cymosum to identify the beneficial phytochemicals.

Buckwheat is a gluten-free crop under the family Polygonaceae abundant with beneficial phytochemicals that provide significant health benefits. It is cultivated and adapted in diverse ecological zones all over the world. Recently its popularity is expanding as a nutrient-rich healthy food with low-calories. The bioactive compounds in buckwheat are flavonoids (i.e., rutin, quercetin, orientin, isoorientin, vitexin, and isovitexin), fatty acids, polysaccharides, proteins, and amino acids, iminosugars, dietary fiber, fagopyrins, resistant starch, vitamins, and minerals. Buckwheat possesses high nutritional value due to these bioactive compounds. Additionally, several essential bioactive factors that have long been gaining interest because these compounds are beneficial for healing and preventing several human diseases. The present review demonstrates an overview of the recent researches regarding buckwheat phytochemicals and particularly focusing on the distinct function of bioactive components with their health benefits.

Water Shortage Strongly Alters Formation of Calcium Oxalate Druse Crystals and Leaf Traits in Fagopyrum esculentum

Common buckwheat (Fagopyrum esculentum Moench) is a robust plant with high resistance to different environmental constraints. It contains high levels of calcium oxalate (CaOx) druse crystals, although their role remains obscure. The objective was to examine the effects of water shortage on plant biomass partition and leaf traits and formation of CaOx druse crystals in common buckwheat. Buckwheat plants were exposed to favorable and reduced water availability for 28 days. The element composition and morphological, biochemical, physiological and optical traits of the leaves, and the plant biomass were investigated under these conditions. Measurements of photochemical efficiency of photosystem II showed undisturbed functioning for buckwheat exposed to water shortage, apparently due to partially closed stomata and more efficient water regulation. Strong relationships were seen between water-related parameters and Ca, Mn and S content, and size and density of CaOx druse crystals. Redundancy analysis revealed the importance of the size of CaOx druse crystals to explain reflection in the UV range. Water shortage resulted in shorter plants with the same leaf mass (i.e., increased mass:height ratio), which, together with denser leaf tissue and higher content of photosynthetic pigments and protective substances, provides an advantage under extreme weather conditions.

Purification and identification of buckwheat hull flavonoids and its comparative evaluation on antioxidant and cytoprotective activity in vitro

Buckwheat hulls, by-products of buckwheat processing, contain various flavonoids, but the antioxidant capacity and synergy of different flavonoids are unclear. The purpose of this study was to evaluate the antioxidant activity of flavonoid monomers and high-flavonoid component (HBHF) in buckwheat hulls using chemical-based assays and cellular-based assays. Four kinds of flavonoids were identified as rutin, isoorientin, vitexin, and hyperoside from buckwheat hulls. In chemical-based assays, rutin and HBHF showed relatively high free radical scavenging activities and total antioxidant capacities. In cellular-based assays, however, HBHF showed much higher proliferation activity against cell damage than flavonoid monomers when HepG2 cell was oxidatively damaged by H2O2 or high glucose. The cytoprotective activities of flavonoid monomers and HBHF were closely associated with reducing levels of reactive oxygen species (ROS) and malondialdehyde (MDA) or increasing catalase (CAT) activity. In conclusion, buckwheat hull flavonoids are the favorable application candidates for natural antioxidants.

Genetic and genomic research for the development of an efficient breeding system in heterostylous self-incompatible common buckwheat (Fagopyrum esculentum)

Common buckwheat (Fagopyrum esculentum Moench; 2n = 2x = 16) is an annual crop that is cultivated widely around the world and contains an abundance of nutrients and bioactive compounds. However, the yield of buckwheat is low compared to that of other major crops, and it contains proteins that cause allergic reactions in some people. Much research has aimed to improve or eliminate these undesirable traits, and some major advances have recently been made. Here, we review recent advances in buckwheat breeding materials, tools, and methods, including the development of self-compatible lines, genetic maps, a buckwheat genome database, and an efficient breeding strategy. We also describe emerging breeding methods for high-value lines.