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Cadmium (Cd) can adversely damage plant growth. Therefore, understanding the control molecular mechanisms of Cd accumulation will benefit the development of strategies to reduce Cd accumulation in plants. This study performed transcriptomic and metabolomic analyses on the roots of a Cd-tolerant Tartary buckwheat cultivar following 0 h (CK), 6 h (T1), and 48 h (T2) of Cd treatment. The fresh weight and root length were not significantly inhibited under the T1 treatment but they were in the T2 treatment. The root’s ultrastructure was seriously damaged in T2 but not in T1 treatment. This was evidenced by deformed cell walls, altered shape and number of organelles. A total of 449, 999 differentially expressed genes (DEGs) and eight, 37 differentially expressed metabolites (DEMs) were identified in the CK versus T1 and CK versus T2 comparison, respectively. DEGs analysis found that the expression of genes related to cell wall function, glutathione (GSH) metabolism, and phenylpropanoid biosynthesis changed significantly during Cd stress. Several WRKY, MYB, ERF, and bHLH transcription factors and transporters also responded to Cd treatment. Our results indicate that Cd stress affects cell wall function and GSH metabolism and that changes in these pathways might contribute to mechanisms of Cd tolerance 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.

Background Tartary buckwheat seed development is an extremely complex process involving many gene regulatory pathways. MicroRNAs (miRNAs) have been identified as the important negative regulators of gene expression and performed crucial regulatory roles in various plant biological processes. However, whether miRNAs participate in Tartary buckwheat seed development remains unexplored. Results In this study, we first identified 26 miRNA biosynthesis genes in the Tartary buckwheat genome and described their phylogeny and expression profiling. Then we performed small RNA (sRNA) sequencing for Tartary buckwheat seeds at three developmental stages to identify the miRNAs associated with seed development. In total, 230 miRNAs, including 101 conserved and 129 novel miRNAs, were first identified in Tartary buckwheat, and 3268 target genes were successfully predicted. Among these miRNAs, 76 exhibited differential expression during seed development, and 1534 target genes which correspond to 74 differentially expressed miRNAs (DEMs) were identified. Based on integrated analysis of DEMs and their targets expression, 65 miRNA-mRNA interaction pairs (25 DEMs corresponding to 65 target genes) were identified that exhibited significantly opposite expression during Tartary buckwheat seed development, and 6 of the miRNA-mRNA pairs were further verified by quantitative real-time polymerase chain reaction (qRT-PCR) and ligase-mediated rapid amplification of 5′ cDNA ends (5′-RLM-RACE). Functional annotation of the 65 target mRNAs showed that 56 miRNA-mRNA interaction pairs major involved in cell differentiation and proliferation, cell elongation, hormones response, organogenesis, embryo and endosperm development, seed size, mineral elements transport, and flavonoid biosynthesis, which indicated that they are the key miRNA-mRNA pairs for Tartary buckwheat seed development. Conclusions Our findings provided insights for the first time into miRNA-mediated regulatory pathways in Tartary buckwheat seed development and suggested that miRNAs play important role in Tartary buckwheat seed development. These findings will be help to study the roles and regulatory mechanism of miRNAs in Tartary buckwheat seed development.

The aim of the present study is to evaluate the absolute content and accumulation patterns of flavonoid components; to give insight into the accumulation relationships among flavonoid components; to explore the correlation between the content of flavonoid components and the expression of flavonoid biosynthesis genes in Tartary buckwheat seeds; and to construct a biosynthetic pathway on the major flavonoid components in Tartary buckwheat seeds. In total, 61 flavonoid components were absolutely quantified in five Tartary buckwheat varieties, of which 41 existed in all varieties. The content of most flavonoids varied significantly among different varieties or within the same variety. Rutin, quercetin, nicotiflorin, and kaempferol were the dominant flavonoid components in the Tartary buckwheat seeds, accounting for 73.05–81.79% of the total flavonoids. Significantly positive or negative correlations with content accumulation were found between some flavonoid components. Thirty-six flavonoid components displayed four different accumulation patterns in the developing Tartary buckwheat seeds. Seventeen structural genes for flavonoid biosynthesis displayed a significantly positive correlation with the accumulation of most flavonoid components during the development of Tartary buckwheat seeds, and the F3′5′H-3 gene might be the most crucial contributor in determining the total flavonoid content in Tartary buckwheat seeds. A schematic of the biosynthesis pathways for 30 major flavonoids in Tartary buckwheat seeds was constructed. These findings provide an outlook of the flavonoid components and their biosynthesis in Tartary buckwheat seeds and have potential applications in breeding new cultivars with higher flavonoid contents.

Copper (Cu) is an essential micronutrient for plant growth and development; Cu homeostasis in plant is maintained by the important functions of Ctr/COPT-type Cu transporters. Although the COPT genes have been identified in Arabidopsis thaliana and rice, little is known about Cu transporters in maize. In this study, three-members of putative maize Cu transporters (ZmCOPT 1, 2 and 3) are identified. ZmCOPT genes have expression in all of the tested tissues, including roots, stems, leaves and flowers (male and female), and their expression levels vary responding to stress due to Cu-deficiency and excess. Functional complementation and overexpression together with Cu uptake measurements in ZmCOPTs-transformed ctr1⊿ctr2⊿mutant strain or the wild type strain of Saccharomyces cerevisiae show that the three ZmCOPT members possess the ability to be Cu transporters. Among these, ZmCOPT1 and ZmCOPT2 have high-affinity while ZmCOPT3 has low-affinity. In addition, ZmCOPT2 tend to specifically transport Cu (I) but no other bivalent metal ions.

BBX (B-box), a zinc finger transcription factor with one or two B-box domains, plays an important role in plant photomorphogenesis, growth, and development as well as response to environmental changes. In this study, 28 Tartary buckwheat BBX ( FtBBX ) genes were identified and screened using a comparison program. Their physicochemical properties, gene structures, conserved motifs, distribution in chromosomal, and phylogeny of the coding proteins, as well as their expression patterns, were analyzed. In addition, multiple collinearity analysis in three monocots and three dicot species illustrated that the BBX proteins identified from monocots clustered separately from those of dicots. Moreover, the expression of 11 candidate BBX genes with probable involvement in the regulation of anthocyanin biosynthesis was analyzed in the sprouts of Tartary buckwheat during light treatment. The results of gene structure analysis showed that all the 28 BBX genes contained B-box domain, three genes lacked introns, and these genes were unevenly distributed on the other seven chromosomes except for chromosome 6. The 28 proteins contained 10 conserved motifs and could be divided into five subfamilies. BBX genes of Tartary buckwheat showed varying expression under different conditions demonstrating that FtBBXs might play important roles in Tartary buckwheat growth and development. This study lays a foundation for further understanding of Tartary buckwheat BBX genes and their functions in growth and development as well as regulation of pigmentation in Tartary buckwheat.

Increasing abiotic stress, particularly salinity, poses a significant threat to the germination and seedling development of Tartary buckwheat, thereby limiting its yield potential and broader cultivation. Given Tartary buckwheat’s rich nutritional profile and inherent stress adaptability, enhancing seed tolerance to abiotic stress is essential for ensuring food security and the development of functional food resources. To investigate the role of melatonin in mitigating abiotic stress, seeds of the cultivar ‘Jinqiaomai 2’ were primed with varying melatonin concentrations (with water as the control) at multiple time points. The effects of salt stress on germination and seedling quality were evaluated to determine optimal priming conditions. Subsequent analyses examined seed vigor and physiological and biochemical responses during storage under high temperature and humidity, room temperature, and low-temperature conditions. The results showed that a 3 h melatonin priming consistently resulted in high germination rates (98.7–100.0%). Notably, melatonin at 50 μmol·L−1 was identified as the optimal concentration, significantly improving seedling growth under salinity stress, with increases of 61.1% in seedling length, 59.3% in root length, and 38.9% in root fresh weight compared with the control. Across all storage environments, melatonin-primed seeds exhibited superior vigor and enhanced antioxidant enzyme activity relative to water-primed controls. In conclusion, melatonin priming at an appropriate concentration and duration effectively enhanced the vigor of Tartary buckwheat seeds and alleviated the adverse effects of salinity on germination and storage resilience. However, improved seeds may possess a limited safe storage window and should be sown promptly rather than stored long-term.

Energy-field-assisted cutting exhibits excellent ability to reduce cutting force and improve machining quality. In this study, a magnetic field was applied in an innovative way to aid in the cutting process, and magnetic-field-assisted scratching experiments of single-crystal copper were carried out. It was found that magnetic-field-assisted scratching increased the actual scratching force due to the additional Lorentz force in the cutting process. However, the friction coefficient of the magnetic-field-assisted scratching was reduced by 19.4% due to the tribological modification effect on tool/chip contact. Meanwhile, magnetic-field-assisted scratching was conducive to decreasing the degree of chip deformation, reducing microburrs on the machined surface, and obtaining a surface roughness reduction of an average of 26.8%. The possible reason for this effect was that the presence of a magnetic field in the cutting process promoted the dislocation slip of metal materials. The results indicated that magnetic-field-assisted cutting improves the machinability in the metal cutting process.

Key message ZmMGT10 was specifically expressed in maize roots and induced by a deficiency of magnesium. Overexpression of ZmMGT10 restored growth deficiency of the Salmonella typhimurium MM281 strain and enhanced the tolerance in Arabidopsis to stress induced by low magnesium levels by increasing uptake of Mg 2+ via roots. CorA/MRS2/MGT-type Mg 2+ transporters play a significant role in maintaining magnesium (Mg) homeostasis in plants. Although the maize CorA/MRS2/MGT family comprises of 12 members, currently no member has been functionally characterized. Here, we report the isolation and functional characterization of ZmMGT10 from the maize MRS2/MGT gene family. ZmMGT10 has a typical structure feature which includes two conserved TMs near the C-terminal end and an altered AMN tripeptide motif. The high sequence similarity and close phylogenetic relationship indicates that ZmMGT10 is probably the counterpart of Arabidopsis AtMGT6 . The complementation of the Salmonella typhimurium mutated MM281 strain indicates that ZmMGT10 possesses the ability to transport Mg 2+ . ZmMGT10 was specifically expressed in the plant roots and it can be stimulated by a deficiency of Mg. Transgenic Arabidopsis plants which overexpressed ZmMGT10 grew more vigorously than wild-type plants under low Mg conditions, exhibited by longer root length, higher plant fresh weight and chlorophyll content, suggesting ZmMGT10 was essential for plant growth and development under low Mg conditions. Further investigations found that high accumulation of Mg 2+ occurred in transgenic plants attributed to improved Mg 2+ uptake and thereby enhanced tolerance to Mg deficiency. Results from this investigation illustrate that ZmMGT10 is a Mg transporter of maize which can enhance the tolerance to Mg deficient conditions by improving Mg 2+ uptake in the transgenic plants of Arabidopsis .

Tartary buckwheat has increasingly become the focus of people’s attention due to its powerful health benefits. Golden buckwheat is a traditional Chinese medicine. People have begun to utilize it through wide hybridization to further enhance the health benefits of Tartary buckwheat. To study the genetic stability of the interspecific hybrids of Tartary buckwheat with golden buckwheat, and to provide scientific basis for the interspecific cross breeding of buckwheat, the mitotic chromosomes of two buckwheat double lines and their interspecific hybrids with golden buckwheat were subjected to observe the karyotypes. The results showed as follows: (1) The two autotetraploid Tartary buckwheat lines (Long Black-4T and Daku-1) have chromosome number 2n = 32. The karyotype formula of 2n = 4x = 32 consisted of 16 pairs of metacentric chromosomes for Long Black-4T (TTTT) while Daku-1 (TTTT) has 1sm + 7m Gui Jinqiao 4 with 2n = 32 has a karyotype formula of 2n = 4x = 32 that consisted 1sm + 6m + 1M (genome M) and 2sm + 5m + 1M (genome M’). The normal fertile tetraploid hybrid F1 plants between Long Black-4T and Gui Jinqiao 4 has 2n = 4x = [1sm + 7m (M), 1sm + 7m (M’), 14m + 2M (TT)]. The normal fertile variety Gui Jinku 1 from the above hybrid progenies shows 2n = 4x = [3sm + 5m (M), 2sm + 6m (M’), 16m (TT)], indicating an increment of sm chromosomes by rearrangements of chromosome structure in the M and M’ genomes. The above parents and their hybrids with the MM’TT genome show fertility. A plant from F2 of the above cross, showing highly infertility, has 2n = 3x= [1sm + 7m (M), 1sm + 7m (M’), 8m (T)]; and back cross progeny plant from Daku 1/Gui Jinqiao 4 F2//Gui Jinqiao 2 golden buckwheat has 2n = 4x = [16m (MM), 5sm + 3m (M’), 1sm + 7m (T)], showed high infertility, which is caused by genome aneuploidy and non-even ploidy. The above shows that there are obvious variations of genome karyotypes from the same parent, indicated by certain chromosome structural rearrangements in genomes T, M, and M’.