China is one of the four major centers of agricultural origin in the world, where two distinct agricultural systems were established: the rice-based system represented by the middle and lower reaches of the Yangtze River, and the dryland farming system represented by the Yellow River basin. Historical records and archaeological evidence indicate that as early as the Shang Dynasty, oracle bone inscriptions already mentioned crops such as millet (Setaria italica), broomcorn millet (Panicum miliaceum), wheat, rice, and soybeans. During the pre-Qin period, the concept of the ‘Five Grains’ was established, and in The Book of Songs (Shijing), the broader term ‘Hundred Grains’ also appeared as a general reference to food crops. However, it is noteworthy that buckwheat, a crop native to China, has long been absent from these documented grain systems. This omission is inconsistent with the fact that buckwheat is an indigenous Chinese crop with high genetic diversity, significant local variation, and a long history of cultivation and domestication in cold mountainous regions. This study conducts a systematic review of the literature related to the origin, evolution, and spread of buckwheat, integrating recent findings in archaeobotany and genetic diversity analysis. Following internationally accepted principles for identifying crop origin centers, and drawing on historical texts, biological characteristics, and distribution patterns, the study presents comprehensive evidence supporting the hypothesis that southwestern China-particularly Yunnan, Sichuan, Guizhou, and the southern fringe of the Qinghai-Tibet Plateau-is the center of origin, genetic diversity, and domestication for Fagopyrum species. There are 23 species of Fagopyrum identified in China, including three cultivated species-common buckwheat (F. esculentum), tartary buckwheat (F. tataricum), and golden buckwheat (F. cymosum)-and 20 wild species, the majority of which are concentrated in southwestern China. This region is not only the native habitat of the ancestral subspecies of common and tartary buckwheat (F. esculentum ssp. ancestrale and F. tataricum ssp. potanini), but also the area with the richest diversity of Fagopyrum, strongly indicating its status as the origin center. Furthermore, molecular markers and phylogenetic studies confirm close genetic relationships between wild and cultivated buckwheat species in this region, providing key evidence for reconstructing domestication pathways. With advancements in modern research, buckwheat has gained recognition not only for its short growth cycle, broad adaptability, and resilience to poor soils and cold climates, making it suitable for cultivation in remote and mountainous areas, but also for its grain's rich content of proteins, flavonoids, and functional sugar alcohols. As a highly promising functional coarse grain crop, buckwheat is particularly suited to the development of characteristic agriculture in central and western China. It holds significant potential for ecological sustainability, nutritional health, and high-value agricultural development, and is expected to play an important role in China's national nutrition strategy and food diversity conservation. This study provides theoretical and empirical evidence to support the scientific designation of China as the center of origin and domestication of buckwheat, laying a solid foundation for future work in germplasm conservation, variety improvement, and industrial development.

Tartary buckwheat (Fagopyrum tataricum), an underutilized pseudocereal, possesses significant nutritional and pharmaceutical properties and demonstrates resistance to drought and nutrient deficiency. However, this environmentally sustainable crop exhibits sensitivity to salt stress, which can induce water loss, stomatal closure, impair photosynthesis and metabolism, and diminish yield and quality of Tartary buckwheat. Understanding the mechanisms of salt stress tolerance in buckwheat is therefore crucial. This study identified a locus containing 35 candidate genes on chromosome 2 that shows significant association with salt tolerance of Tartary buckwheat through genome-wide association analysis (GWAS). Transcriptome analysis demonstrated that the serine/threonine-protein kinase Aurora-3 (FtAUR3) family gene exhibited upregulation in response to salt stress. A single nucleotide deletion in the FtAUR3 promoter results in elevated FtAUR3 expression and enhanced salt tolerance in Tartary buckwheat. Overexpression of FtAUR3 in buckwheat hairy roots promotes the accumulation of flavonoids, including rutin and cinnamic acid, while inducing the expression of flavonoid biosynthesis genes, such as PAL, C4H, F3H, and F3´H, under salt stress. Additionally, overexpression of FtAUR3 in Arabidopsis thaliana induced the expression of salt-resistant genes (salt-resistant genes (SOS1), AVP1, etc.) and enhanced salt tolerance compared to wild type plants. Under salt stress, FtAUR3 significantly enhances the levels of reactive oxygen species pathway components, including superoxide dismutase, catalase, and peroxidase, thereby improving plant salt tolerance. The study demonstrated that FtAUR3 interacts with the critical enzyme FtGAPB in the reactive oxygen species (ROS) pathway, suggesting a potential mechanism through which FtAUR3 contributes to ROS signaling. These findings indicate that FtAUR3 plays a crucial positive role in Tartary buckwheat resistance against salt stress.

Drought is a major environmental constraint that significantly affects seedling emergence, yield, and quality of Tartary buckwheat, thereby hindering the development of its industry. However, the molecular mechanisms underlying drought tolerance genes in Tartary buckwheat remain largely unexplored. Alcohol dehydrogenase (ADH), an essential plant protein, plays a crucial role in growth, development, and stress responses; however, its specific role in drought resistance remains unclear. This study identifies an ADH gene, FtADH1, using a membership function value of drought tolerance (MFVD) combined with a genome-wide association study (GWAS) and transcriptomic profiles that confer drought tolerance in Tartary buckwheat. Our findings demonstrated that the overexpression of FtADH1 in Arabidopsis and Tartary buckwheat hairy roots enhances drought tolerance by promoting root elongation and mitigating elevated levels of reactive oxygen species (ROS). Our findings demonstrate that FtADH1 can enhance drought tolerance in Tartary buckwheat and Arabidopsis. This study identifies FtADH1 as a new regulator of Tartary buckwheat's ROS levels and stress responses, functioning by regulating protective enzyme activities at a high level to scavenge ROS and modulating root growth under drought stress. Further, it identifies proteins interacting with FtADH1 through a prokaryotic expression pull-down assay combined with mass spectrometry, revealing that FtADH1 interacts explicitly with the S-adenosyl-L-methionine (SAM) synthetase protein, FtSAMS1. Overexpression of FtSAMS1 enhances ADH enzymatic activity, leading to increased SAM content in overexpressing Tartary buckwheat hairy roots under water-deficit conditions. Additionally, overexpression of FtSAMS1 induces a drought-resistant phenotype in Arabidopsis and Tartary buckwheat hairy roots under drought stress, revealing the biological function of FtADH1. Evolutionary analysis indicates that ADH1 in Fagopyrum species has undergone significant evolutionary events, including duplication and purifying selection, which may contribute to functional diversification and adaptive advantages such as drought resistance in cultivated buckwheat. In summary, this study suggests that FtADH1 is a key contributor to drought tolerance, and its interaction with FtSAMS1 offers promising potential for developing drought-resistant varieties in Tartary buckwheat and its relative species.

Drought is becoming a common threat to crop production. Identifying and utilizing excellent drought-resistant genes is crucial to combating this stress and ensuring global food security by developing drought-resistant crop varieties. Although sugar transporters are involved in stress tolerance in many plants, the sugar transporter gene family of Tartary buckwheat has yet to be systematically analyzed. This study identified 140 sugar transporter genes from the ‘Pinku’ Tartary buckwheat genome and classified them into 10 subfamilies. Structural analysis showed that subfamily SGB/pGlcT had the highest number of introns compared to other subfamilies, and abundant abiotic stress-related cis-acting elements existed in the promoter region. Collinear analysis revealed relatively ancient genes FtSUT7, FtSTP28, FtPLT1, and FtINT2. The expression of sugar transporter genes was screened under various abiotic stresses, which revealed the association of stress tolerance with different sugar transporter genes, i.e., FtERD23, FtINT2, FtpGlcT2, and FtSTP27. Further, we observed that the overexpression of FtERD23 maintains osmotic pressure through glucose transport, which may enhance drought stress tolerance. Moreover, gene co-expression analyses using weighted gene co-expression network analysis (WGCNA) and fuzzy c-means algorithm (FCMA) identified six transcription factors that may regulate FtERD23 expression and are involved in plant drought tolerance. Our systematic analysis provides a theoretical basis for the further functional characterization of sugar transporter genes to improve drought tolerance in Tartary buckwheat and its related species.