BnXTH1 regulates cadmium tolerance by modulating vacuolar compartmentalization and the cadmium binding capacity of cell walls in ramie (Boehmeria nivea).

Xyloglucan endotransglucosylase/hydrolases (XTH) are cell wall-modifying enzymes important in plant response to abiotic stress. However, the role of XTH in cadmium (Cd) tolerance in ramie remains largely unknown. Here, we identified and cloned BnXTH1, a member of the XTH family, in response to Cd stress in ramie. The BnXTH1 promoter (BnXTH1p) demonstrated that MeJA induces the response of BnXTH1p to Cd stress. Moreover, overexpressing BnXTH1 in Boehmeria nivea increased Cd tolerance by significantly increasing the Cd content in the cell wall and decreasing Cd inside ramie cells. Cadmium stress induced BnXTH1-expression and consequently increased xyloglucan endotransglucosylase (XET) activity, leading to high xyloglucan contents and increased hemicellulose contents in ramie. The elevated hemicellulose content increased Cd chelation onto the cell walls and reduced the level of intracellular Cd. Interestingly, overexpressing BnXTH1 significantly increased the content of Cd in vacuoles of ramie and vacuolar compartmentalization genes. Altogether, these results evidence that Cd stress induced MeJA accumulation in ramie, thus, activating BnXTH1 expression and increasing the content of xyloglucan to enhance the hemicellulose binding capacity and increase Cd chelation onto cell walls. BnXTH1 also enhances the vacuolar Cd compartmentalization and reduces the level of Cd entering the organelles and soluble solution.

Waterlogging increases greenhouse gas release and decreases yield in winter rapeseed (Brassica napus L.) seedlings.

A sustainable future depends on increasing agricultural carbon (C) and nitrogen (N) sequestration. Winter rapeseeds are facing severe yield loss after waterlogging due to the effects of extreme rainfall, especially in the seedling stage, where rainfall is most sensitive. Uncertainty exists over the farming greenhouse gas (GHG) release of rapeseed seedlings following the onset of waterlogging. The effect of waterlogging on GHG release and leaf gas exchange in winter rapeseed was examined in a pot experiment. The experiment included waterlogging treatments lasting 7-day and 21-day and normal irrigation as a control treatment. According to our findings, (1) The ecosystem of rapeseed seedlings released methane (CH4) and nitrous oxide (N2O) in a clear up change that was impacted by ongoing waterlogging. Among them, N2O release had a transient rise during the early stages under the effect of seedling fertilizer. (2) The net photosynthetic rate, transpiration rate, stomatal conductance, plant height, soil moisture, and soil oxidation-reduction potential of rapeseed all significantly decreased due to the ongoing waterlogging. However, rapeseed leaves showed a significant increase in intercellular carbon dioxide (CO2) concentration and leaf chlorophyll content values after waterlogging. Additionally, the findings demonstrated an extremely significant increase in the sustained-flux global warming potential of the sum CO2-eq of CH4 and N2O throughout the entire waterlogging stress period. Therefore, continuous waterlogging can increase C and N release from rapeseed seedlings ecosystem and decrease yield. Therefore, we suggest increasing drainage techniques to decrease the release of agricultural GHGs and promote sustainable crop production.

Molecular Mechanisms Regulating Phenylpropanoid Metabolism in Exogenously-Sprayed Ethylene Forage Ramie Based on Transcriptomic and Metabolomic Analyses.

Ramie (Boehmeria nivea [L.] Gaud.), a nutritious animal feed, is rich in protein and produces a variety of secondary metabolites that increase its palatability and functional composition. Ethylene (ETH) is an important plant hormone that regulates the growth and development of various crops. In this study, we investigated the impact of ETH sprays on the growth and metabolism of forage ramie. We explored the mechanism of ETH regulation on the growth and secondary metabolites of forage ramie using transcriptomic and metabolomic analyses. Spraying ramie with ETH elevated the contents of flavonoids and chlorogenic acid and decreased the lignin content in the leaves and stems. A total of 1076 differentially expressed genes (DEGs) and 51 differentially expressed metabolites (DEMs) were identified in the leaves, and 344 DEGs and 55 DEMs were identified in the stems. The DEGs that affect phenylpropanoid metabolism, including BGLU41, LCT, PER63, PER42, PER12, PER10, POD, BAHD1, SHT, and At4g26220 were significantly upregulated in the leaves. Ethylene sprays downregulated tyrosine and chlorogenic acid (3-O-caffeoylquinic acid) in the leaves, but lignin biosynthesis HCT genes, including ACT, BAHD1, and SHT, were up- and downregulated. These changes in expression may ultimately reduce lignin biosynthesis. In addition, the upregulation of caffeoyl CoA-O-methyltransferase (CCoAOMT) may have increased the abundance of its flavonoids. Ethylene significantly downregulated metabolites, affecting phenylpropanoid metabolism in the stems. The differential 4CL and HCT metabolites were downregulated, namely, phenylalanine and tyrosine. Additionally, ETH upregulated 2-hydroxycinnamic acid and the cinnamyl hydroxyl derivatives (caffeic acid and p-coumaric acid). Cinnamic acid is a crucial intermediate in the shikimic acid pathway, which serves as a precursor for the biosynthesis of flavonoids and lignin. The ETH-decreased gene expression and metabolite alteration reduced the lignin levels in the stem. Moreover, the HCT downregulation may explain the inhibited lignin biosynthesis to promote flavonoid biosynthesis. In conclusion, external ETH application can effectively reduce lignin contents and increase the secondary metabolites of ramie without affecting its growth and development. These results provide candidate genes for improving ramie and offer theoretical and practical guidance for cultivating ramie for forage.

Identification of the Xyloglucan Endotransglycosylase/Hydrolase (XTH) Gene Family Members Expressed in Boehmeria nivea in Response to Cadmium Stress.

Xyloglucan endotransglycosylase/hydrolase (XTH) genes play an important role in plant resistance to abiotic stress. However, systematic studies of the response of Boehmeria nivea (ramie) XTH genes (BnXTHs) to cadmium (Cd) stress are lacking. We sought to identify the BnXTH-family genes in ramie through bioinformatics analyses and to investigate their responses to Cd stress. We identified 19 members of the BnXTH gene family from the ramie genome, referred to as BnXTH1-19, among which BnXTH18 and BnXTH19 were located on no chromosomes and the remaining genes were unevenly distributed across 11 chromosomes. The 19 members were divided into four groups, Groups I/II/IIIA/IIIB, according to their phylogenetic relationships, and these groups were supported by analyses of intron-exon structure and conserved motif composition. A highly conserved catalytic site (HDEIDFEFLG) was observed in all BnXTH proteins. Additionally, three gene pairs (BnXTH6-BnXTH16, BnXTH8-BnXTH9, and BnXTH17-BnXTH18) were obtained with a fragment and tandem-repeat event analysis of the ramie genome. An analysis of cisregulatory elements revealed that BnXTH expression might be regulated by multiple hormones and abiotic and biotic stress responses. In particular, 17 cisregulatory elements related to abiotic and biotic stress responses and 11 cisregulatory elements related to hormone responses were identified. We also found that most BnXTH genes responded to Cd stress, and BnXTH1, BnXTH3, BnXTH6, and BnXTH15 were most likely to contribute to the Cd tolerance of ramie, as evidenced by the substantial increases in expression under Cd treatment. Heterologous expression of BnXTH1, BnXTH6, and BnXTH15 significantly enhanced the Cd tolerance of transgenic yeast cells. These results suggest that the BnXTH gene family is involved in Cd stress responses, laying a theoretical foundation for functional studies of BnXTH genes and the innovative breeding of Cd-tolerant ramie.

Transcriptional and Metabolic Characterization of Feeding Ramie Growth Enhanced by a Combined Application of Gibberellin and Ethrel.

Feeding ramie cultivars (Boehmaria nivea L.) are an important feedstock for livestock. Increasing their biomass and improving their nutritional values are essential for animal feeding. Gibberellin (GA3) and ethylene (ETH) are two plant hormones that regulate the growth, development, and metabolism of plants. Herein, we report effects of the GA3 and ETH application on the growth and plant metabolism of feeding ramie in the field. A combination of GA3 and ETH was designed to spray new plants. The two hormones enhanced the growth of plants to produce more biomass. Meanwhile, the two hormones reduced the contents of lignin in leaves and stems, while increased the content of flavonoids in leaves. To understand the potential mechanisms behind these results, we used RNA-seq-based transcriptomics and UPLC-MS/MS-based metabolomics to characterize gene expression and metabolite profiles associated with the treatment of GA3 and ETH. 1562 and 2364 differentially expressed genes (DEGs) were obtained from leaves and stems (treated versus control), respectively. Meanwhile, 99 and 88 differentially accumulated metabolites (DAMs) were annotated from treated versus control leaves and treated versus control stems, respectively. Data mining revealed that both DEGs and DAMs were associated with multiple plant metabolisms, especially plant secondary metabolism. A specific focus on the plant phenylpropanoid pathway identified candidates of DEGs and DEMs that were associated with lignin and flavonoid biosynthesis. Shikimate hydroxycinnamoyl transferase (HCT) is a key enzyme that is involved in the lignin biosynthesis. The gene encoding B. nivea HCT was downregulated in the treated leaves and stems. In addition, genes encoding 4-coumaryl CoA ligase (4CL) and trans-cinnamate 4-monooxygenase (CYP73A), two lignin pathway enzymes, were downregulated in the treated stems. Meanwhile, the reduction in lignin in the treated leaves led to an increase in cinnamic acid and p-coumaryl CoA, two shared substrates of flavonoids that are enhanced in contents. Taken together, these findings indicated that an appropriate combination of GA3 and ETH is an effective strategy to enhance plant growth via altering gene expression and plant secondary metabolism for biomass-enhanced and value-improved feeding ramie.

Molecular Tools and Their Applications in Developing Salt-Tolerant Soybean (Glycine max L.) Cultivars.

Abiotic stresses are one of the significant threats to soybean (Glycine max L.) growth and yields worldwide. Soybean has a crucial role in the global food supply chain and food security and contributes the main protein share compared to other crops. Hence, there is a vast scientific saddle on soybean researchers to develop tolerant genotypes to meet the growing need of food for the huge population. A large portion of cultivated land is damaged by salinity stress, and the situation worsens yearly. In past years, many attempts have increased soybean resilience to salinity stress. Different molecular techniques such as quantitative trait loci mapping (QTL), genetic engineering, transcriptome, transcription factor analysis (TFs), CRISPR/Cas9, as well as other conventional methods are used for the breeding of salt-tolerant cultivars of soybean to safeguard its yield under changing environments. These powerful genetic tools ensure sustainable soybean yields, preserving genetic variability for future use. Only a few reports about a detailed overview of soybean salinity tolerance have been published. Therefore, this review focuses on a detailed overview of several molecular techniques for soybean salinity tolerance and draws a future research direction. Thus, the updated review will provide complete guidelines for researchers working on the genetic mechanism of salinity tolerance in soybean.

The Role of Hemicellulose in Cadmium Tolerance in Ramie (Boehmeria nivea (L.) Gaud.).

Ramie cell walls play an important role in cadmium (Cd) detoxification. However, the Cd binding capacity of the cell wall components and the cell wall compositions among ramie species remains unclear. Therefore, this study compared two ramie populations ('Dazhuhuangbaima' (low-Cd-accumulating population) and 'Zhongzhu 1' (high-Cd-accumulating population)) with different Cd enrichment characteristics. The two ramie populations were treated with 0, 25, and 75 mg kg-1 Cd for 30 days; then, their root length, plant height, biomass, Cd enrichment in the organs, subcellular Cd distribution, Cd content in the cell wall polysaccharides, and hemicellulose content were determined. The root length, plant height, biomass, and Cd enrichment in all organs were significantly higher (p ≤ 0.05) in 'Zhongzhu 1' than in 'Dazhuhuangbaima' under Cd stress. In addition, the subcellular Cd distribution analysis revealed that Cd was mainly found in the cell wall in both ramie populations. Among the cell wall fractions, Cd was mainly bound to the hemicelluloses, with 60.38-73.10% and 50.05-64.45% Cd accumulating in the 'Zhongzhu 1' and 'Dazhuhuangbaima' cell wall hemicelluloses, respectively. However, the Cd concentration in the 'Zhongzhu 1' hemicellulose was significantly higher (p ≤ 0.05) than that in the 'Dazhuhuangbaima' hemicellulose. Hemicellulose content analysis further revealed that the hemicellulose concentration increased with the Cd concentration in both populations, but it was significantly higher (p ≤ 0.05) in 'Zhongzhu 1' than in 'Dazhuhuangbaima' across all Cd treatments. Thus, ramie copes under Cd stress by increasing the hemicellulose content in the cell wall. The findings in this study confirm that hemicellulose is the main enrichment site for Cd in ramie. It also provides a theoretical basis for Cd enrichment breeding in ramie.

Improving Drought Stress Tolerance in Ramie (Boehmeria nivea L.) Using Molecular Techniques.

Ramie is one of the most significant fiber crops and contributes to good quality fiber. Drought stress (DS) is one of the most devastating abiotic factors which is accountable for a substantial loss in crop growth and production and disturbing sustainable crop production. DS impairs growth, plant water relation, and nutrient uptake. Ramie has evolved a series of defense responses to cope with DS. There are numerous genes regulating the drought tolerance (DT) mechanism in ramie. The morphological and physiological mechanism of DT is well-studied; however, modified methods would be more effective. The use of novel genome editing tools like clustered regularly interspaced short palindromic repeats (CRISPR) is being used to edit the recessive genes in crops to modify their function. The transgenic approaches are used to develop several drought-tolerant varieties in ramie, and further identification of tolerant genes is needed for an effective breeding plan. Quantitative trait loci (QTLs) mapping, transcription factors (TFs) and speed breeding are highly studied techniques, and these would lead to the development of drought-resilient ramie cultivars. The use of hormones in enhancing crop growth and development under water scarcity circumstances is critical; however, using different concentrations and testing genotypes in changing environments would be helpful to sort the tolerant genotypes. Since plants use various ways to counter DS, investigating mechanisms of DT in plants will lead to improved DT in ramie. This critical review summarized the recent advancements on DT in ramie using novel molecular techniques. This information would help ramie breeders to conduct research studies and develop drought tolerant ramie cultivars.

Integrative plasma proteomic and microRNA analysis of Jersey cattle in response to high-altitude hypoxia.

Blood has been widely collected and analyzed for diagnosing and monitoring diseases in humans and animals; a range of plasma proteins and peptide can be used as biomarkers to describe pathological or physiological status. Changes in the environment such as high-altitude hypoxia (HAH) can lead to adaptive changes in the blood system of mammals. However, the adaptation mechanism induced by HAH remains unclear. In this study, we used 12 multiparous Jersey cattle (400 ± 35 kg, average 3 yr old, dry period). We applied an iTRAQ (isobaric tags for relative and absolute quantitation) proteomics approach and microRNA (miRNA) microarray to explore differences in the plasma proteomic and miRNA profiles of Jersey cattle exposed to HAH conditions in Nyingchi, Tibet (altitude 3,000 m) and HAH-free conditions in Shenyang, China (altitude 50 m). Such quantitative proteomic strategies are suitable for accurate and comprehensive prediction of miRNA targets. In total, 264 differentially expressed proteins (127 upregulated, fold-change >1.2; 137 downregulated, fold-change <0.8) and 47 differential miRNAs (25 upregulated, fold-change >2; 22 downregulated, fold-change <0.5) were observed in the HAH-stressed group compared with the HAH-free group. Integrative analysis of proteomic and miRNA profiles demonstrated that the biological processes associated with differentially expressed proteins were immune response, complement system, and conjugation system. Integrative analysis of canonical pathways showed that most were associated with acute phase response signaling (z-score = -0.125), liver X receptor/retinoid X receptor (LXR/RXR) activation pathway (z-score = 1.134), coagulation system (z-score = -0.943), and complement system (z-score = -0.632). The current results indicated that Jersey cattle exposed to HAH could adapt to that condition through regulation of inflammatory homeostasis by inhibiting the acute phase response, coagulation system, and complement system and promoting LXR/RXR activation.

Effects of dietary supplementation of Acanthopanax senticosus on gastrointestinal tract development in calves.

Twenty-four newborn Holstein dairy male calves (with initial body weight of 38 ± 3.0 kg) were used in a randomized block design experiment to determine effects of dietary supplementation of Acanthopanax senticosus (AS) on gastrointestinal tract development. Calves were fed milk (10%/body weight) three times at 06.00, 12.00 and 18.00 hours daily with one to four treatments during the experimental periods (4 to 28 days): no supplementation of AS (control group, CG); 1.0 g/L•time of micro-powder AS (MP); 1.0 g/L•time of superfine powder AS (SP); or 1.0 g/L•time of coarse powder AS (CP). On days 7, 14, 21 and 28, 20 mL blood samples were collected at 06.00 hours before the morning feeding. At the end of the trial (28 days), all calves were euthanized, and tissue samples were taken and placed in 4% buffered formaldehyde for analyses. In the rumen of MP treatment, compared with the CG treatment, wall thickness and papillae diameter was both significantly lower (P<0.05), while crypt depth was significantly greater (P<0.05). In the duodenum, villi diameter of AS supplemented treatments was significantly lower than that of CG treatment (P<0.05). Results indicate that calves during sucking period supplemented with AS as MP style could promote gastrointestinal development.