Exogenous melatonin improves germination rate in buckwheat under high temperature stress by regulating seed physiological and biochemical characteristics.

The germinations of three common buckwheat (Fagopyrum esculentum) varieties and two Tartary buckwheat (Fagopyrum tataricum) varieties seeds are known to be affected by high temperature. However, little is known about the physiological mechanism affecting germination and the effect of melatonin (MT) on buckwheat seed germination under high temperature. This work studied the effects of exogenous MT on buckwheat seed germination under high temperature. MT was sprayed. The parameters, including growth, and physiological factors, were examined. The results showed that exogenous MT significantly increased the germination rate (GR), germination potential (GP), radicle length (RL), and fresh weight (FW) of these buckwheat seeds under high-temperature stress and enhanced the content of osmotic adjustment substances and enzyme activity. Comprehensive analysis revealed that under high-temperature stress during germination, antioxidant enzymes play a predominant role, while osmotic adjustment substances work synergistically to reduce the extent of damage to the membrane structure, serving as the primary key indicators for studying high-temperature resistance. Consequently, our results showed that MT had a positive protective effect on buckwheat seeds exposed to high temperature stress, providing a theoretical basis for improving the ability to adapt to high temperature environments.

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

BACKGROUND: 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. RESULTS: Here, by analyzing the population genomics of 567 accessions collected worldwide and reviewing historical documents, we find that Tartary buckwheat originated in the Himalayan region and then spread southwest possibly along with the migration of the Yi people, a minority in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. CONCLUSIONS: This study provides both comprehensive insights into the origin and domestication of, and a foundation for molecular breeding for, Tartary buckwheat.

Effect of co-treatment of microwave and exogenous l-phenylalanine on the enrichment of flavonoids in Tartary buckwheat sprouts.

BACKGROUND: Tartary buckwheat is rich in flavonoids. The application of physical processing technology and exogenous materials treatment can effectively promote grain germination and the accumulation of bioactive secondary metabolites. The content of four flavonoids, the activities of key enzymes (phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), flavonol synthase (FLS)) and the expression of key enzyme genes (FtPAL, FtCHI, FtFLS1, FtFLS2) in Tartary buckwheat sprouts treated with microwave and l-phenylalanine (l-Phe) were investigated, and the relationship between them was analyzed to explore the mechanism of promoting flavonoid accumulation, and to provide a theoretical basis for the development of functional Tartary buckwheat sprout food. RESULTS: Germination can promote the synthesis of flavonoids. The contents of chlorogenic acid and rutin in 7-day sprouts increased by 13 420.63% and 225.12% compared with seeds, respectively. Under the best treatment condition T3 (microwave 250 W, 90 s, 2.9 mmol L-1 L-Phe), the specific activities of PAL, CHI and FLS in 5-day-old sprouts increased by 47.84%, 53.04% and 28.02% compared with control check (CK), respectively; and the expression of FtPAL, FtCHI and FtFlS1 increased by 39.84%, 24.78% and 33.72% compared with CK, respectively. Correlation analysis showed that the content of flavonoids in Tartary buckwheat sprouts was significantly positively correlated with the specific activities of key enzymes (P < 0.01) and dynamically correlated with genes related to the synthesis of three enzymes. CONCLUSION: It suggested that microwave and l-Phe treatment may promote the synthesis of flavonoids by promoting the expression of key enzymes genes in phenylpropane metabolism and controlling the activity of key enzymes in phenylpropane metabolism. © 2022 Society of Chemical Industry.

Label-free quantitative proteomics reveals the mechanism of microwave-induced Tartary buckwheat germination and flavonoids enrichment.

The objective of this study was to reveal the mechanism underlying the effects of microwave treatment on Tartary buckwheat germination and flavonoids enrichment. Label-free quantitative proteomic analysis showed that Tartary buckwheat germinated at 3, 5, and 7 days after 300 W/50 s microwave treatment had 7, 5, and 5 differentially expressed proteins (DEPs) compared to those of control. These DEPs are mainly related to energy production and conversion, gene expression, and flavonoids metabolism. Based on KEGG analysis, the DEPs were mainly enriched in photosynthesis, RNA polymerase, flavonoid biosynthesis, phenylalanine metabolism, and phenylpropanoid biosynthesis metabolic pathways. Further, the upregulation of phenylalanine ammonia-lyase and flavonol synthase protein enzymes promoted germination and flavonoids accumulation in Tartary buckwheat. These findings reveal the mechanism of Tartary buckwheat germination and the enrichment of flavonoids induced by microwaves and provide a scientific basis for the development of functional foods for Tartary buckwheat.

Comparison of buckwheat genomes reveals the genetic basis of metabolomic divergence and ecotype differentiation.

Golden buckwheat (Fagopyrum dibotrys or Fagopyrum cymosum) and Tartary buckwheat (Fagopyrum tataricum) belong to the Polygonaceae and the Fagopyrum genus is rich in flavonoids. Golden buckwheat is a wild relative of Tartary buckwheat, yet golden buckwheat is a traditional Chinese herbal medicine and Tartary buckwheat is a food crop. The genetic basis of adaptive divergence between these two buckwheats is poorly understood. Here, we assembled a high-quality chromosome-level genome of golden buckwheat and found a one-to-one syntenic relationship with the chromosomes of Tartary buckwheat. Two large inversions were identified that differentiate golden buckwheat and Tartary buckwheat. Metabolomic and genetic comparisons of golden buckwheat and Tartary buckwheat indicate an amplified copy number of FdCHI, FdF3H, FdDFR, and FdLAR gene families in golden buckwheat, and a parallel increase in medicinal flavonoid content. Resequencing of 34 wild golden buckwheat accessions across the two morphologically distinct ecotypes identified candidate genes, including FdMYB44 and FdCRF4, putatively involved in flavonoid accumulation and differentiation of plant architecture, respectively. Our comparative genomic study provides abundant genomic resources of genomic divergent variation to improve buckwheat with excellent nutritional and medicinal value.

Streptomyces xanthii sp. nov. and Streptomyces roseirectus sp. nov. isolated from a Chinese medicinal plant.

Two strains of Actinobacteria, designated CRXT-Y-14T and CRXT-G-22T, were isolated from the healthy leaves and seeds, respectively, of a medicinal plant Xanthium sibiricum. Their taxonomic positions were determined using a polyphasic approach. Strain CRXT-Y-14T produced flexuous chains of smooth-surfaced spores. Strain CRXT-G-22T produced straight chains of smooth-surfaced spores. Their morphological features were consistent with the diagnostic characteristics of members of the genus Streptomyces. The results of 16S rRNA gene sequence analyses indicated two strains represented members of the genus Streptomyces. CRXT-Y-14T shared 99.3, 98.9, 98.8 % sequence similarities to Streptomyces atriruber NRRL B-24165T, Streptomyces avermitilis MA-4680T and Streptomyces davaonensis JCM 4913T, respectively. Whilst CRXT-G-22T exhibited highest similarity to Streptomyces acidiscabies ATCC 49003T (98.9 %). The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the closest phylogenetic neighbours of strains CRXT-Y-14T and CRXT-G-22T were S. atriruber NRRL B-24165T and S. acidiscabies ATCC 49003T, respectively. The phylogenomic analyses further confirmed the relative relationship between strain CRXT-G-22T and S. acidiscabies ATCC 49003T, but indicated that CRXT-Y-14T could represent a novel species of the genus Streptomyce. However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between CRXT-Y-14T and strain CRXT-G-22T, between CRXT-Y-14T and S. atriruber NRRL B-24165T, and between CRXT-G-22T and S. acidiscabies ATCC 49003T were 85.4 and 23.2 %, 85.8 and 23.9 % and 89.1 and 34.1 %, respectively, far below the 95~96 and 70 % cut-off points recommended for delineating species. Furthermore, these two novel isolates were distinctly differentiated from their relatives in the genus Streptomyces with respect to phenotypic and chemotaxonomic characteristics. On the basis of these data, CRXT-Y-14T and CRXT-G-22T clearly represent two novel species within the genus Streptomyces, for which the names Streptomyces xanthii sp. nov. (type strain CRXT-Y-14T = MCCC 1K04966T= JCM 34527T) and Streptomyces roseirectus sp. nov. (type CRXT-G-22T = MCCC 1K04979T= JCM 34565T) are proposed.

Streptomyces aquilus sp. nov., a novel actinomycete isolated from a Chinese medicinal plant.

The taxonomic position of a novel actinomycete isolate, designated strain GGCR-6T, isolated from the healthy leaves of Xanthium sibiricum collected from the botanic garden of Hunan University of Science and Technology in Hunan province, PR China, was determined by a polyphasic approach. GGCR-6T grew well on ISP series media and formed well-developed, branched substrate hyphae and aerial mycelium that differentiated into straight spore chains consisting of cylindrical spores with smooth surfaces. The diagnostic diamino acid was ll-diaminopimelic acid. The major menaquinones were MK-9(H8), MK-9(H2), MK-9 and MK-9(H6). The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphotidylinositol and phosphatidylinositol mannosides. The predominant fatty acids were C16 : 1ω9c, iso-C16 : 0 and C16 : 0. The phenotypic characteristics of GGCR-6T indicated that it represented a member of the genus Streptomyces. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that GGCR-6T was most closely related to Streptomyces cyaneus NRRL B2296T and Streptomyces griseoruber NRRL B1818T. However, the digital DNA-DNA hybridization, the average nucleotide identity and the multi locus sequence analysis evolutionary distance clearly separate GGCR-6T from the phylogenetically closely related species. Furthermore, the novel isolate was distinctly differentiated from S. cyaneus NRRL B2296T and S. griseoruber NRRL B1818T by morphological, physiological and biochemical characteristics. Based on these data, strain GGCR-6T should be designated as a representative of a novel species of the genus Streptomyces, for which the name Streptomyces aquilus sp. nov. is proposed. The type strain is strain GGCR-6T (=CICC 11055T=JCM 33584T).