Xuemei Zhu's research while affiliated with Sichuan Agricultural University and other places

Soil cadmium (Cd) contamination seriously reduces the production and product quality of Tartary buckwheat (Fagopyrum tataricum), and strategies are urgently needed to mitigate these adverse influences. Herein, we investigated the effect of salicylic acid (SA) on Tartary buckwheat seedlings grown in Cd-contaminated soil in terms of Cd tolerance and accumulation. The results showed that 75–100 µmol L−1 SA treatment enhanced the Cd tolerance of Tartary buckwheat, as reflected by the significant increase in plant height and root and shoot biomass, as well as largely mitigated oxidative stress. Moreover, 100 µmol L−1 SA considerably reduced the stem and leaf Cd concentration by 60% and 47%, respectively, which is a consequence of increased root biomass and root Cd retention with promoted Cd partitioning into cell wall and immobile chemical forms. Transcriptome analysis also revealed the upregulation of the genes responsible for cell wall biosynthesis and antioxidative activities in roots, especially secondary cell wall synthesis. The present study determines that 100 µmol L−1 is the best SA concentration for reducing Cd accumulation and toxicity in Tartary buckwheat and indicates the important role of root in Cd stress in this species.

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 analys is showed that an R2R3-MYB transcription factor FtMYB43 positively regulates the synthesis of procyanidin. Glycoside hydrolase gene FtSAGH1 is characterized responsible for the release of active salicylic acid, the precursor of aspirin and indispensably in plant defense. UDP-glucosyltransferase gene FtUGT74L2 is characterized 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 facilita te genetic improvement of medicinal properties and disease resistance in Tartary buckwheat.

Metal tolerance proteins (MTP) as divalent cation transporters are essential for plant metal tolerance and homeostasis. However, the characterization and the definitive phylogeny of the MTP gene family in Fagopyrum tartaricum, and their roles in response to metal stress are still unknown. In the present study, MTP genes in Fagopyrum tartaricum were identified, and their phylogenetic relationships, structural characteristics, physicochemical parameters, as well as expression profiles under five metal stresses including Fe, Mn, Cu, Zn, and Cd were also investigated. Phylogenetic relationship analysis showed that 12 Fagopyrum tartaricum MTP genes were classified into three major clusters and seven groups. All FtMTPs had typical structural features of the MTP gene family and were predicted to be located in the cell vacuole. The upstream region of FtMTPs contained abundant cis-acting elements, implying their functions in development progress and stress response. Tissue-specific expression analysis results indicated the regulation of FtMTPs in the growth and development of Fagopyrum tataricum. Besides, the expression of most FtMTP genes could be induced by multiple metals and showed different expression patterns under at least two metal stresses. These findings provide useful information for the research of the metal tolerance mechanism and genetic improvement of Fagopyrum tataricum.

Buckwheat is a promising pseudo cereal and its cultivation history can be traced back to thousands of years ago in China. Nowadays, buckwheat is not only an ordinary crop but also a symbol of healthy life because of its rich nutritional and pharmacological properties. In this research, the current suitable areas of 19 wild buckwheat species were analyzed by the MaxEnt model, which proved that southwestern China was the diversity center of buckwheat. Their morphological characteristics and geographical distribution were analyzed for the first time. In addition, it was found that the change of buckwheat cultivation in three periods might be related to the green revolution of main crops and national policies. Meanwhile, the Sustainable Yield Index (SYI) value of buckwheat in China was the lowest from 1959 to 2016. Through the MaxEnt model, the potentially suitable areas of wild buckwheat would contract while cultivated buckwheat would expand under climate change. Accordingly, the diversity of wild buckwheat will decrease. Therefore, it is necessary to protect buckwheat resources as much as possible to strengthen the development and utilization of buckwheat resources. Moreover, the promotion of buckwheat diversity will be an important trade-off between food security, population growth, and land use under climate change.

Mining activities could induce severe heavy metal pollution in soil and surface water, which would consequently pose potential ecological environment risks and human health risks. In this research, total 82 agricultural soil samples and 34 water samples were collected from a special area that surrounding a lead-zinc mine. Pollution level, source apportionment, ecological and health risks of heavy metals were evaluated based on the concentrations of cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). According to the results, Cd and Zn were obviously enriched metals in agricultural soil in the study area, meanwhile, the potential risks which calculated by geo-accumulation index were showed a high ecological risk due to high concentration of Cd found in local agricultural soil. Additionally, heavy metal sources analyzed by the PMF model could be classified into four categories: mining activity (Mn), parent material (Cr, Ni), atmospheric deposition caused by industrial and mining activities (Pb, Zn, Cd) and agricultural activities (Cu). Compared with the values specified by corresponding water quality standard, the heavy metals content in surface water were below these values except Cd, while the content of seven heavy metals in drinking water was within the safe limits. The bioavailability of Cd, Pb and Zn in soil were higher than other metals, and when the bioavailability of metals was consideration into health risk assessment, the total HI and TCR values were far below the accepted risk levels. Though human health risks were within the safe margin, the toxic hazards of heavy metals to residents and ecological should be taken into consideration.

Global warming, energy consumption (EC), and food security have led to increasing concern about carbon emissions (CEs) from agriculture, especially CEs from rice cultivation in China. However, there are few studies on CEs from rice production in Southwest China (SWC) (including Yunnan Province (YNP), Sichuan Province, Guizhou Province, and Chongqing Municipality (CQM)), which has complex topography and climatic conditions. Here, a set of indicators based on yield, economic output, EC, and CEs were proposed to describe the performance of rice production in SWC during 2004–2016. The research results reflected that (1) the share of indirect EC of rice production was 75.46% in SWC, more than 90% of which originated from nitrogen fertilizer, compound fertilizer, and pesticides; (2) direct CEs contributed to 55.20% of the total CEs in SWC during the study period, and fertilizer production and utilization were the largest contributor (45.03%) to CEs in this area, followed by paddy fields (38.61%); (3) CQM had the worst performance in SWC in terms of CE intensity of economic output and profit from land use; (4) YNP had the greatest EC intensity based on yield, the greatest CE intensity based on sowing area and yield, and the worst production structure and comprehensive performance; and (5) the structure of rice production was optimized to different degrees in SWC, but no obvious improvement was seen in relationships between yield, economic output, EC, and CEs in this area. Therefore, measures should be taken to reduce the EC intensity and CE intensity of rice production in YNP, and rice plantation methods with high yield and fine quality should be emphasized in the other three administrative regions.

Fagopyrum cymosum has been considered as a traditional medicinal plant that belongs to Fagopyrum, which has exhibited great pharmaceutical potential due to its abundant flavonoid accumulation. The hairy roots induced by Agrobacterium rhizogenes has been utilized to produce valuable specialized metabolites or reveals plant metabolic processes, whereas the underlying regulatory networks of flavonoid biosynthesis in hairy roots of F. cymosum remained unexplored. Here, the regulatory transcription factor TrMYB4 cloned from Trifolium repens with purple striped leaves was considered to investigate the mechanism of flavonoids biosynthesis in hairy roots of F. cymosum. Results showed that the expression of key genes involved in rutin biosynthesis pathway from TrMYB4 hairy roots were significantly up-regulated compared with non-transgenic hairy roots, while the content of total flavonoids and rutin in TrMYB4 hairy roots also increased consistently. It revealed the TrMYB4 transcription factor could regulate the rutin biosynthesis in F. cymosum. Meanwhile, our research provided a theoretical reference for the industrial production of rutin using F. cymosum hairy roots.

Tartary buckwheat tea (TBT) is the most popular and widely consumed buckwheat product in many countries. However, the perfect quality control standards for TBT were still lacking, and the content of heavy metals in TBT and their health risks to consumers were still unknown. In this research, the total phenolic content, total flavonoid content, and antioxidant capacity as well as six metal contents and their health risks in TBT were detected. The results showed that the total phenolic content, total flavonoid content, and antioxidant capacity varied significantly among different types of TBT. Meanwhile, six metal concentrations in TBT leaves and infusions decreased in the order of Zn, Cu, Cr, Ni, Pb, and Cd. Health risk assessment indicated that the heavy metal intake only from TBT would not cause a noncarcinogenic risk to consumers. However, a strong carcinogenic risk of Cr in TBT for consumers should be paid more attention.

Buckwheat is an important functional food material with high nutritional value. However, it is still a difficult task for the taxonomy studies of wild buckwheat that are only based on morphology. In order to demonstrate the most efficient DNA barcode in the phylogenetic research of buckwheat, promote the investigation of wild buckwheat, and also reveal the phylogenetic relationship between Fagopyrum species, psbE-psbL and ndhA intron were validated here, which previously have been proved to be promising DNA barcode candidates for phylogenetic studies in genera Fagopyrum. Meanwhile, ndhA intron + psbE-psbL and matK + psbE-psbL could distinguish the relationship between species clearly. Combining the results of morphology and molecular markers, we suggested the buckwheat species should be divided into two subgroups, one subgroup consisted of F. tataricum, F. esculentum, F. cymosum and its related wild species, and the other subgroup included other wild buckwheat species. Our results could fulfill molecular markers of taxonomy research in genera Fagopyrum, promote wild buckwheat species identification, and assist in the use of wild buckwheat resources in the future. Additionally, the phylogenetic relationship revealed here could provide valuable information for molecular breeding of buckwheat and provide reference for inter-species hybridization.