Recent Progress in Perennial Buckwheat Development

Seed traits inheritance in Fagopyrum esculentum Moench. based on image analysis method

Common buckwheat (Fagopyrum esculentum Moench.) is one of the most important orphan crops worldwide. Various research efforts have been done to improve cultivation methods to enhance important agronomic traits such as productivity and biotic/abiotic resistance. One important aspect is the seed trait, which has not been extensively studied due to the time-consuming and tedious nature of its examination. Despite this, understanding seed traits is crucial for meeting consumer needs and optimizing crop yields. Therefore, the aim of the study is to investigate the inheritance of common buckwheat seed traits-such as shape, size, and coat color-using an image-based approach. This method allows for the analysis of a large number of seeds with a level of accuracy and precision that was previously unattainable. The results indicate that seed coat color is inherited maternally. Notably, the parameters in size had substantial increases acting like overdominance. The number of seeds that were harvested from F1s of each cross differed a lot depending on the cross combinations and pin/thrum type. In addition, seed size had large reduction in F1s from the different seed-sized parents, especially in thrum type. These may show that there could be cross barriers. The results revealed trends of maternal inheritance for seed shape and coat color in buckwheat, an area that has not been extensively studied. These findings could support buckwheat breeding efforts, helping to address market needs and food demands in the face of significant climate change.

Nutrition, health benefits, and processing of sand rice (Agriophyllum squarrosum): Comparisons with quinoa and buckwheat

The dual pressures of climate change and population growth have made the development of new grains a necessity. Agriophyllum squarrosum (sand rice) has high adaptability to harsh environments and does not occupy agricultural land. It is widely cultivated and consumed in Central Asia. Sand rice, together with quinoa and buckwheat, belongs to the same pseudocereals group with rich nutritional value and gluten-free properties; however, its nutritional composition and health benefits differ from those of quinoa and buckwheat. Sand rice seeds are a rich source of nutrients and bioactive compounds, including proteins, amino acids, unsaturated fatty acids, and crude fiber, which are similar to those in buckwheat and quinoa; however, their starch content is relatively low. Sand rice seeds also possess phenolic acids and flavonoids, which exhibit antioxidant, anticancer, anti-diabetes, and anti-inflammatory properties. Furthermore, sand rice extracts are considered suitable for treating some chronic diseases. Overall, sand rice is considered a good plant-based food that can be used to develop various functional foods and beverages or mixed with other grains in different recipes. However, advancements in the processing technology of sand rice-based foods are required to fully exploit the potential of sand rice in the food industry to improve human health. This review analyzes the current understanding of the nutritional content of sand rice by comparing it with that of quinoa and buckwheat. Furthermore, its potential medicinal activity and feasibility as a functional ingredient to improve food quality is discussed.

Exploration of unique starch physicochemical properties of novel buckwheat lines created by crossing Golden buckwheat and Tatary buckwheat

Buckwheat is considered as a healthy cereal food, and it is essential to cultivate new buckwheat lines with good starch physicochemical properties for both consumers and food producers. Six novel buckwheat (Duoku, Dk) were generated by crossing of Golden buckwheat and Tatary buckwheat, and their kernel appearance properties and starch physicochemical properties were analyzed together with one domestic line (Cimiqiao) and one wild line (Yeku). The results showed that Dk samples had better appearance properties than two control samples. The Dk samples showed lower amylose content, similar amylopectin molecular structure and chain length distributions, and larger starch granules compared with Cimiqiao. The digestion results showed that two Dk samples: Dk6 & Dk9 had high resistant starch content; while the other two Dk samples: Dk37 & Dk38 had a steady glucose releasing rate. The Dk samples also showed high gelatinization temperature, indicating they were good raw materials for producing glass noodle. This study proved that Dk buckwheat had unique starch physicochemical properties, and could be used as new food materials in the future.

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.

Plastome comparison and phylogenomics of Fagopyrum (Polygonaceae): insights into sequence differences between Fagopyrum and its related taxa

BACKGROUND

Fagopyrum (Polygonaceae) is a small plant lineage comprised of more than fifteen economically and medicinally important species. However, the phylogenetic relationships of the genus are not well explored, and the characteristics of Fagopyrum chloroplast genomes (plastomes) remain poorly understood so far. It restricts the comprehension of species diversity in Fagopyrum. Therefore, a comparative plastome analysis and comprehensive phylogenomic analyses are required to reveal the taxonomic relationship among species of Fagopyrum.

RESULTS

In the current study, 12 plastomes were sequenced and assembled from eight species and two varieties of Fagopyrum. In the comparative analysis and phylogenetic analysis, eight previously published plastomes of Fagopyrum were also included. A total of 49 plastomes of other genera in Polygonaceae were retrieved from GenBank and used for comparative analysis with Fagopyrum. The variation of the Fagopyrum plastomes is mainly reflected in the size and boundaries of inverted repeat/single copy (IR/SC) regions. Fagopyrum is a relatively basal taxon in the phylogenomic framework of Polygonaceae comprising a relatively smaller plastome size (158,768-159,985 bp) than another genus of Polygonaceae (158,851-170,232 bp). A few genera of Polygonaceae have nested distribution of the IR/SC boundary variations. Although most species of Fagopyrum show the same IRb/SC boundary with species of Polygonaceae, only a few species show different IRa/SC boundaries. The phylogenomic analyses of Fagopyrum supported the cymosum and urophyllum groups and resolved the systematic position of subclades within the urophyllum group. Moreover, the repeat sequence types and numbers were found different between groups of Fagopyrum. The plastome sequence identity showed significant differences between intra-group and inter-group.

CONCLUSIONS

The deletions of intergenic regions cause a short length of Fagopyrum plastomes, which may be the main reason for plastome size diversity in Polygonaceae species. The phylogenomic reconstruction combined with the characteristics comparison of plastomes supports grouping within Fagopyrum. The outcome of these genome resources may facilitate the taxonomy, germplasm resources identification as well as plant breeding of Fagopyrum.

Integrated Transcriptomics and Widely Targeted Metabolomics Analyses Provide Insights Into Flavonoid Biosynthesis in the Rhizomes of Golden Buckwheat (Fagopyrum cymosum)

Golden buckwheat (Fagopyrum cymosum) is used in Traditional Chinese Medicine. It has received attention because of the high value of its various medicinal and nutritional metabolites, especially flavonoids (catechin and epicatechin). However, the metabolites and their encoding genes in golden buckwheat have not yet been identified in the global landscape. This study performed transcriptomics and widely targeted metabolomics analyses for the first time on rhizomes of golden buckwheat. As a result, 10,191 differentially expressed genes (DEGs) and 297 differentially regulated metabolites (DRMs) were identified, among which the flavonoid biosynthesis pathway was enriched in both transcriptome and metabolome. The integration analyses of the transcriptome and the metabolome revealed a network related to catechin, in which four metabolites and 14 genes interacted with each other. Subsequently, an SG5 R2R3-MYB transcription factor, named FcMYB1, was identified as a transcriptional activator in catechin biosynthesis, as it was positively correlated to eight flavonoid biosynthesis genes in their expression patterns and was directly bound to the promoters of FcLAR2 and FcF3'H1 by yeast one hybrid analysis. Finally, a flavonoid biosynthesis pathway was proposed in the rhizomes of golden buckwheat, including 13 metabolites, 11 genes encoding 9 enzymes, and 1 MYB transcription factor. The expression of 12 DEGs were validated by qRT-PCR, resulting in a good agreement with the Pearson R ranging from 0.83 to 1. The study provided a comprehensive flavonoid biosynthesis and regulatory network of golden buckwheat.

Biotechnological Methods for Buckwheat Breeding

The Fagopyrum genus includes two cultivated species, namely common buckwheat (F. esculentum Moench) and Tartary buckwheat (F. tataricum Gaertn.), and more than 25 wild buckwheat species. The goal of breeders is to improve the properties of cultivated buckwheat with methods of classical breeding, with the support of biotechnological methods or a combination of both. In this paper, we reviewed the possibility to use transcriptomics, genomics, interspecific hybridization, tissue cultures and plant regeneration, molecular markers, genetic transformation, and genome editing to aid in both the breeding of buckwheat and in the identification and production of metabolites important for preserving human health. The key problems in buckwheat breeding are the unknown mode of inheritance of most traits, associated with crop yield and the synthesis of medicinal compounds, low seed yield, shedding of seeds, differential flowering and seed set on branches, and unknown action of genes responsible for the synthesis of buckwheat metabolites of pharmaceutical and medicinal interest.

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.

Nutraceutical crop buckwheat: a concealed wealth in the lap of Himalayas

Buckwheat is a crop that has gained considerable interest worldwide due to its nutritional, economical, and pharmaceutical values. To ensure food and nutritional security in a scenario of global climate change, this pseudocereal is a competent alternative to staple crops. With rising knowledge regarding the nutraceutical potential, the popularity of this species is expected to increase further in coming years. The main bioactive component of this species is rutin that has been proven to have a wide range of health-promoting benefits. Due to breeding constraints, asynchronous maturity, seed shattering, and restricted distribution, this species holds the status of an underutilized or neglected crop in many parts of the world. In the North-western Himalayan zone, it is an integral part of local dietary intake and is grown as a second crop after harvesting barley and peas. Fagopyrum esculentum and F. tataricum are the species of buckwheat cultivated in the North-western Himalayas. However, more studies in the direction of conservation, utilization, and genetic amelioration of plant genetic resources are needed to sustain food security in Southeast Asia. The present review paper accentuates the multicore potential of buckwheat besides highlighting the commercial and pharmaceutical perspective. This article also focuses on the conservation and sustainable utilization of Himalayan gene pools, desirable agronomic traits, and genetic diversity besides focusing on the biochemical and molecular response of Fagopyrum to biotic and abiotic stress including modulation of the rutin content. The role of biotechnological interventions and future prospects are also summarized.