FtbZIP12 Positively Regulates Responses to Osmotic Stress in Tartary Buckwheat.

ABFs play a key role in regulating plant osmotic stress. However, in Tartary buckwheat, data on the role of ABF genes in osmotic stress remain limited and its associated mechanism in osmoregulation remain nebulous. Herein, a novel ABF family in Tartary buckwheat, FtbZIP12, was cloned and characterized. FtbZIP12 is a transcriptional activator located in the nucleus; its expression is induced by NaCl, mannitol, and abscisic acid (ABA). Atopic expression of FtbZIP12 in Arabidopsis promoted seed germination, reduced damage to primary roots, and improved the tolerance of seedlings to osmotic stress. The quantitative realtime polymerase chain reaction (RT-qPCR) results showed that the expressions of the typical genes related to stress, the SOS pathway, and the proline synthesis pathway in Arabidopsis were significantly (p < 0.05) upregulated under osmotic stress. FtbZIP12 improved the osmotic pressure resistance by reducing the damage caused by reactive oxygen species to plants and maintained plant homeostasis by upregulating the expression of genes related to stress, osmotic regulation, and ion homeostasis. This study identified a key candidate gene for understanding the mechanism underlying osmotic-stress-regulated function in Tartary buckwheat, thereby providing a theoretical basis for improving its yield and quality.

Genome-Wide Identification, Evolution, and Expression Pattern Analysis of the GATA Gene Family in Tartary Buckwheat (Fagopyrum tataricum).

GATA is a transcription factor that exerts a vital function in plant growth and development, physiological metabolism, and environmental responses. However, the GATA gene family has rarely been studied in Tartary buckwheat since the completion of its genome. This study used bioinformatics methods to identify GATA genes of Tartary buckwheat and to analyze their subfamily classification, structural composition, and developmental evolution, as well as to discuss the expression patterns of FtGATA genes in different subfamilies. The twenty-eight identified FtGATA genes in the Tartary buckwheat genome were divided into four subfamilies and distributed on eight chromosomes. One pair of tandem repeat genes and eight pairs of fragments were found in chromosome mapping. Spatiotemporal expression patterns of eight FtGATA genes in different subfamilies indicated that the FtGATA gene family has regulatory roles in tissue specificity, fruit development, abiotic stress, and hormonal responses. This study creates a theoretical and scientific foundation for further research on the evolutionary relationship and biological function of FtGATA.

Physiological and Biochemical Regulation Mechanism of Exogenous Hydrogen Peroxide in Alleviating NaCl Stress Toxicity in Tartary Buckwheat (Fagopyrum tataricum (L.) Gaertn).

We aimed to elucidate the physiological and biochemical mechanism by which exogenous hydrogen peroxide (H2O2) alleviates salt stress toxicity in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn). Tartary buckwheat "Chuanqiao-2" under 150 mmol·L-1 salt (NaCl) stress was treated with 5 or 10 mmol·L-1 H2O2, and seedling growth, physiology and biochemistry, and related gene expression were studied. Treatment with 5 mmol·L-1 H2O2 significantly increased plant height (PH), fresh and dry weights of shoots (SFWs/SDWs) and roots (RFWs/RDWs), leaf length (LL) and area (LA), and relative water content (LRWC); increased chlorophyll a (Chl a) and b (Chl b) contents; improved fluorescence parameters; enhanced antioxidant enzyme activity and content; and reduced malondialdehyde (MDA) content. Expressions of all stress-related and enzyme-related genes were up-regulated. The F3'H gene (flavonoid synthesis pathway) exhibited similar up-regulation under 10 mmol·L-1 H2O2 treatment. Correlation and principal component analyses showed that 5 mmol·L-1 H2O2 could significantly alleviate the toxic effect of salt stress on Tartary buckwheat. Our results show that exogenous 5 mmol·L-1 H2O2 can alleviate the inhibitory or toxic effects of 150 mmol·L-1 NaCl stress on Tartary buckwheat by promoting growth, enhancing photosynthesis, improving enzymatic reactions, reducing membrane lipid peroxidation, and inducing the expression of related genes.

Genome­wide identification, phylogenetic and expression pattern analysis of GATA family genes in foxtail millet (Setaria italica).

BACKGROUND: Transcription factors (TFs) play important roles in plants. Among the major TFs, GATA plays a crucial role in plant development, growth, and stress responses. However, there have been few studies on the GATA gene family in foxtail millet (Setaria italica). The release of the foxtail millet reference genome presents an opportunity for the genome-wide characterization of these GATA genes. RESULTS: In this study, we identified 28 GATA genes in foxtail millet distributed on seven chromosomes. According to the classification method of GATA members in Arabidopsis, SiGATA was divided into four subfamilies, namely subfamilies I, II, III, and IV. Structural analysis of the SiGATA genes showed that subfamily III had more introns than other subfamilies, and a large number of cis-acting elements were abundant in the promoter region of the SiGATA genes. Three tandem duplications and five segmental duplications were found among SiGATA genes. Tissue-specific results showed that the SiGATA genes were mainly expressed in foxtail millet leaves, followed by peels and seeds. Many genes were significantly induced under the eight abiotic stresses, such as SiGATA10, SiGATA16, SiGATA18, and SiGATA25, which deserve further attention. CONCLUSIONS: Collectively, these findings will be helpful for further in-depth studies of the biological function of SiGATA, and will provide a reference for the future molecular breeding of foxtail millet.

Pretreatment with H2O2 Alleviates the Negative Impacts of NaCl Stress on Seed Germination of Tartary Buckwheat (Fagopyrum tataricum).

Soil salinization is one of the main abiotic stress factors impacting the growth of crops and the agricultural industry today. Thus, we aimed to investigate the effects of H2O2 pretreatment on seed germination in Tartary buckwheat (Fagopyrum tataricum) seeds under salt stress and to evaluate this species' salt tolerance. Through the preliminary experiment, this study used 50 mmol L-1 NaCl solution to induce seed stress. After soaking for 12 h in different H2O2 concentrations, seeds were laid in Petri dishes with 50 mmol L-1 NaCl for seven days and the germination parameters and physiological indicators were measured to screen the optimal H2O2 pretreatment concentration and the salt tolerance index. Our results indicated that pretreatment with 5-10 mmol L-1 H2O2 was most effective in alleviating NaCl's impacts on the seeds' germination parameters. Furthermore, the growth and material accumulation of seedlings was promoted; catalase, superoxide dismutase activity, and proline content were enhanced; and malondialdehyde content was reduced. Principal component analysis and stepwise regression revealed six key indicators that had a significant impact on the salt tolerance characteristics of F. tataricum, namely, germination potential, shoot fresh weight, root surface area, root average diameter, catalase activity, and superoxide dismutase activity.

First Report of Botryosphaeria dothidea Causing Gray Mold on Tartary Buckwheat in Southwest China.

Tartary buckwheat (Fagopyrum tataricum, Polygonaceae) is an annual plant originating in Southwest China. It has a short growth cycle, barren soil tolerance, and strong stress resistance (Zhang et al. 2021). Because of its high content of proteins, starch, trace elements, phenols, and dietary fiber, Tartary buckwheat is beneficial to the human body and hence has received widespread attention (Joshi et al. 2019; Dc ja, B, et al. 2020). In the period from September to November 2020, a diseased plant infected with gray mold was found among M2 generation plants treated using ethyl methanesulfonate (EMS) in a location with potted Tartary buckwheat plants in Huaxi District, Guiyang City, Guizhou Province, China. The diseased plant started to show symptoms during the initial flowering stage; water-soaked spots appeared at first, that the spots increased in size and turned into light brown patches, with the leaf edges scorched brown. In severe cases, the leaves turned yellow, the diseased spots became dry, and finally the leaves necrotic (Figure 1A). Among the leaves that showed disease symptoms, severely susceptible leaves were selected; a piece of tissue (2×2 mm) was removed at the junction of the diseased and healthy tissues. The tissue was then soaked in 75% ethanol for 2 to 3 s, transferred to 1% sodium hypochlorite solution and soaked for 3 min, rinsed three times with sterile water, and placed on sterilized filter paper to dry. Sterile tweezers were used to transfer the tissue blocks to Potato Dextrose Agar medium (Bio-Rad Ltd. Com, USA) containing a Streptomyces-Penicillium mixture (100 µg/mL), and they were incubated on this medium for 7 to 10 days at 25°C and 70% humidity under 16 h light and 8 h dark conditions. The colonies were white at the early stages, with developed aerial hyphae; subsequently, they gradually turned gray-green (Figure 1B). In the later stages, the back of the colony was black and piles of conidia could be seen (Figure 1C). The conidia are scattered, which were colorless and transparent, fusiform or fusiform, with a size of 8.02-11.13 µm×2.06-3.22 µm (average=9.51 µm×2.69 µm, n=50) (Figure 1D). Based on their morphological characteristics, These cultural and morphological characteristics were consistent with the descriptions of as B. dothidea (Fan et al. 2021). The ITS1/ITS4 (Mills et al. 1992), Bt-2a/Bt-2b primers (Glass and Donaldson 1995), and EF1-728F/EF1-986R (Slippers et al. 2004) were amplified and sequenced to analyze the ITS region, ß-tubulin genes translation elongation factor 1-α (TEF1-α), and translation elongation factor 1-α (TEF1-α), respectively. According to BLAST search in GenBank, the sequences of ITS (MZ326853), TUB2 (MZ399162) and TEF1-α (MZ399163) had 99.40%, 100% and 100% similarity to sequences NR111146.1, AY236927.1, and AY236898.1 of B. dothidea ex-type strain CMW8000, respectively. The three nucleotide sequences were concatenated together, and MEGA-X (with the neighbor-joining method) with 1,000 bootstraps was used to construct a phylogenetic tree. The results showed that our isolate was closely related to B. dothidea (Figure 2). Healthy Tartary buckwheat from the M2 generation was used for the pathogenicity test. Disinfect with 75% alcohol and 1×105 mL-1 of spore suspension was sprayed on the leaves. Each treatment included three plants, and it was repeated three times with sterile water as control. The treatments were kept in a houseat25°C for 24 h, then transferred it to the natural environment of 22℃ to 28℃,and sterile water was sprayed every morning and evening to keep the leaves moist. After 10 days, the symptoms seen in the field appeared on the treated plants (Figure 1E), but the control plants did not show any symptoms (Figure 1F). The diseased parts of the leaves were isolated and cultured again, and the isolates were consistent with the original inoculum. Thus, the study conformed to Koch's postulates. B. dothidea is a fungus with no host preference in the genus Botryosphaeria (Botryosphaeriaceae, Botryosphaeriales). It can cause canker, leaf spots, trunk diseases, fruit rot and die-back of many important wood plants all over the world (Marsberg et al.2017). Recently, it was reported that B. dothidea caused soybean canker in China (Chen et al.2021), but there have been no reports of B. dothidea causing Tartary buckwheat gray mold. To the best of our knowledge, this is the first report of B. dothidea causing gray mold on Tartary buckwheat. This finding will provide a basis for the prevention and treatment of Tartary buckwheat gray mold.