Identification of a novel marker and its associated laccase gene for regulating ear length in tropical and subtropical maize lines.

KEY MESSAGE: This study revealed the identification of a novel gene, Zm00001d042906, that regulates maize ear length by modulating lignin synthesis and reported a molecular marker for selecting maize lines with elongated ears. Maize ear length has garnered considerable attention due to its high correlation with yield. In this study, six maize inbred lines of significant importance in maize breeding were used as parents. The temperate maize inbred line Ye107, characterized by a short ear, was crossed with five tropical or subtropical inbred lines featuring longer ears, creating a multi-parent population displaying significant variations in ear length. Through genome-wide association studies and mutation analysis, the A/G variation at SNP_183573532 on chromosome 3 was identified as an effective site for discriminating long-ear maize. Furthermore, the associated gene Zm00001d042906 was found to correlate with maize ear length. Zm00001d042906 was functionally annotated as a laccase (Lac4), which showed activity and influenced lignin synthesis in the midsection cells of the cob, thereby regulating maize ear length. This study further reports a novel molecular marker and a new gene that can assist maize breeding programs in selecting varieties with elongated ears.

Whole genome sequencing and analysis of Armillaria gallica Jzi34 symbiotic with Gastrodia elata.

BACKGROUND: Armillaria species are plant pathogens, but a few Armillaria species can establish a symbiotic relationship with Gastrodia elata, a rootless and leafless orchid, that is used as a Chinese herbal medicine. Armillaria is a nutrient source for the growth of G. elata. However, there are few reports on the molecular mechanism of symbiosis between Armillaria species and G. elata. The genome sequencing and analysis of Armillaria symbiotic with G. elata would provide genomic information for further studying the molecular mechanism of symbiosis. RESULTS: The de novo genome assembly was performed with the PacBio Sequel platform and Illumina NovaSeq PE150 for the A. gallica Jzi34 strain, which was symbiotic with G. elata. Its genome assembly contained ~ 79.9 Mbp and consisted of 60 contigs with an N50 of 2,535,910 bp. There were only 4.1% repetitive sequences in the genome assembly. Functional annotation analysis revealed a total of 16,280 protein coding genes. Compared with the other five genomes of Armillaria, the carbohydrate enzyme gene family of the genome was significantly contracted, while it had the largest set of glycosyl transferase (GT) genes. It also had an expansion of auxiliary activity enzymes AA3-2 gene subfamily and cytochrome P450 genes. The synteny analysis result of P450 genes reveals that the evolutionary relationship of P450 proteins between A. gallica Jzi34 and other four Armillaria was complex. CONCLUSIONS: These characteristics may be beneficial for establishing a symbiotic relationship with G. elata. These results explore the characteristics of A. gallica Jzi34 from a genomic perspective and provide an important genomic resource for further detailed study of Armillaria. This will help to further study the symbiotic mechanism between A. gallica and G. elata.

Mapping of Lymph Node Metastasis and Efficacy Index in Thoracic Esophageal Squamous Cell Carcinoma: A Large-Scale Retrospective Analysis.

BACKGROUND: Esophageal squamous cell carcinoma has a high mortality rate in China. The metastatic pattern in the lymph nodes and the value of their dissection on the overall survival of these patients remain controversial. The primary aim of this study was to provide a basis for accurate staging of esophageal cancer and to identify the relationship between esophageal cancer surgery, lymph node dissection, and overall survival rates. METHODS: We utilized our hospital database to retrospectively review the data of 1727 patients with esophageal cancer who underwent R0 esophagectomy from January 2010 to December 2017. The lymph nodes were defined according to Japanese Classification of Esophageal Cancer, 11th Edition. The Efficacy Index (EI) was calculated by multiplying the frequency (%) of metastases to a zone and the 5-year survival rate (%) of patients with metastases to that zone, and then dividing by 100. RESULTS: The EI was high in the supraclavicular and mediastinal zones in patients with upper esophageal tumors, and the EI of 101R was 17.39, which was the highest among the lymph node stations. In patients with middle esophageal tumors, the EI was highest in the mediastinal zone, followed by the celiac and supraclavicular zones. Furthermore, the EI was highest in the celiac zone, followed by the mediastinal zones in patients with lower esophageal tumors. CONCLUSIONS: The EI of resected lymph nodes was found to vary between stations and was related to the primary location of the tumor.

Rho2 involved in development, stress response and pathogenicity of Fusarium oxysporum.

Rho GTPases regulate the activity of cell wall biosynthesis, actin assembly and polar cell secretion. However, the function of Rho GTPase in filamentous fungi is poorly understood. To understand the role of Rho2 GTPase in Fusarium oxysporum, which is one of root rot pathogens of Panax notoginseng, △rho2 mutant was constructed. Phenotypes of △rho2, including conidiation, germination of spores, stresses (osmotic-, cell membrane-, cell wall disturbing-, metal-, and high temperature-) tolerance and pathogenicity were analyzed. The results showed that the growth of △rho2 was destroyed under cell wall disturbing stress and high temperature stress, suggesting that Rho2 regulated the response of F. oxysporum to cell wall synthesis inhibitors and high temperature stress. Germination of spores and pathogenicity to P. notoginseng were reduced in △rho2 mutant. Western blot results showed that rho2 deletion increased the phosphorylation level of Mpk1. To identify genes regulated by Rho2, transcriptome sequencing was carried out. 2477 genes were identified as upregulated genes and 2177 genes were identified as downregulated genes after rho2 was deleted. These genes provide clues for further study of rho2 function.

Enhancement production of lipid and unsaturation of fatty acids in Cryptococcus humicola via addition of calcium ion.

Lipids synthesized by oleaginous yeasts are considered to be the best candidates for biodiesel production. Cryptococcus humicola as an oleaginous yeast accumulated lipid in cells. In order to optimize the conditions for lipid production, different carbon and nitrogen sources were used and metals were added into the medium. Ca2+ addition increased the lipid production greatly. Xylose and peptone were optimal carbon source and nitrogen source, respectively for lipid accumulation. Response surface experiment results revealed that the accumulation of lipid could be maximized when the xylose, peptone and Ca2+ concentration was 61 g/L, 4.31 g/L, 0.67 mmol/L. C16 and C18 fatty acid account for about 91% of the total fatty acids. The most abundant fatty acid was oleic acid (42.68%), followed by palmitic acid (29.7%) and stearic acid (13.87%). The addition of Ca2+ increased the content of unsaturated fatty acids (such as C16:1 and C18:1) and improved the unsaturation of fatty acids. Quantitative real time PCR analysis revealed that expression of genes related to lipid biosynthesis showed up-regulated by Ca2+ treatment. This study provided a strategy for increase in lipid production and content of unsaturated fatty acids.

The interaction of MYB, bHLH and WD40 transcription factors in red pear (Pyrus pyrifolia) peel.

KEY MESSAGE: Sunlight enhanced peel color and significantly up-regulated the expression of PyMYB10 and PybHLH genes. MYB-bHLH-WD40 transcriptional complex forms in the light and is involved in regulating anthocyanin accumulation in the peel. Anthocyanin is the major pigment in the peel of Yunnan red pear (Pyrus pyrifolia (Burm.) Nak.). A transcriptional activation protein complex, involving members of the transcription factor classes of MYB, bHLH and WD40, regulates anthocyanin biosynthesis. This complex was examined in the peel of red pear. In order to clarify the interaction of PyMYB10, PybHLH and PyWD40, fruit were bagged then peel samples collected 0, 3, 5, and 7 days after bag removal. Samples were used for Western blotting and protein interaction analysis. The results showed that sunlight enhanced peel color and significantly up-regulated the expression of both PyMYB10 and PybHLH genes. Co-immunoprecipitation (Co-IP) analysis showed that PybHLH interacted with PyMYB10 or PyWD40, and PyMYB10 interacted with PyWD40. Using onion cells as a model system, bimolecular fluorescence complementation (BiFC) confirmed these interactions and showed that the interaction localized to the nuclei. GST Pull down and Far-Western blotting assays demonstrated that PybHLH interacted with PyMYB10 or PyWD40, respectively, and PyMYB10 interacted with PyWD40 in vitro. In addition, EMSA assay showed that PyMYB10 can directly bind to the promoter of the gene encoding the anthocyanin biosynthesis enzyme anthocyanidin synthase (PyANS). Taken together, these results showed that the ternary complex of PyMYB10, PybHLH and PyWD40 transcription factors forms to regulate anthocyanin biosynthesis and accumulation in Yunnan red pear.

A small proportion of litter-derived nitrogen is assimilated by plant biomass or immobilized in sediments regardless of harvest management as detected by 15N-labeled Phragmites litter in a constructed wetland.

Emergent aquatic macrophytes play an important role in the removal of nutrients in constructed wetlands (CWs). However, plant biomass supplies litter after the onset of senescence. Although litter-derived nitrogen (N) has been considered a nutrient source for the internal loading that may reduce CW performance, little is known about the quantitative N dynamics associated with litter decomposition. Thus, a controversial question remains about whether plant harvest is needed to manage CWs. In this study, we evaluated the decomposition and the fate of N derived from 15N-labeled Phragmites litter in a CW for 1 year. To simulate respective natural conditions, two treatments, including (1) a single winter harvest and (2) no harvest where the latter supplies a greater stem litterfall, were compared. Although the dry weight of the added stem litter was approximately 4.7 times larger in the no harvest plot than in the harvest plot, the total N content of the initial 15N-labeled litter was only 1.2 times higher in the no harvest plot than in the harvest plots because of the low N concentration in the stem litter. The litter functioned as a minor N sink within the first 6 months of decomposition, and it then shifted to functioning as a minor N source after 1 year of decomposition. The recovery of litter-derived N in the sediment and plant biomass was low (less than 10% of the initial litter N), and much of the remaining N might have been released into ambient water or lost through denitrification. Furthermore, our results suggested a potentially low contribution of litter-derived N to internal N loading for at least 1 year regardless of the harvest management treatment.

Overexpression of a peroxidase gene (AtPrx64) of Arabidopsis thaliana in tobacco improves plant's tolerance to aluminum stress.

KEY MESSAGE: AtPrx64 is one of the peroxidases gene up-regulated in Al stress and has some functions in the formation of plant second cell wall. Its overexpression may improve plant tolerance to Al by some ways. Studies on its function under Al stress may help us to understand the mechanism of plant tolerance to Al stress. In Arabidopsis thaliana, the expressions of some genes (AtPrxs) encoding class III plant peroxidases have been found to be either up-regulated or down-regulated under aluminum (Al) stress. Among 73 genes that encode AtPrxs in Arabidopsis, AtPrx64 is always up-regulated by Al stress, suggesting this gene plays protective roles in response to such stress. In this study, transgenic tobacco plants were generated to examine the effects of overexpressing of AtPrx64 gene on the tolerance to Al stress. The results showed that overexpression of AtPrx64 gene increased the root growth and reduced the accumulation of Al and ROS in the roots. Compared with wild type controls, transgenic tobaccos had much less soluble proteins and malondialdehyde in roots and much more root citrate exudation. The activity of plasma membrane (PM) H+-ATPase, the phosphorylation of PM H+-ATPase and its interaction with 14-3-3 proteins increased in transgenic tobaccos; moreover, the content of lignin in root tips also increased. Taken together, these results showed that overexpression of AtPrx64 gene might enhance the tolerance of tobacco to Al stress.

Effect of Phragmites japonicus harvest frequency and timing on dry matter yield and nutritive value.

Phragmites is a cosmopolitan perennial emergent macrophyte that is distributed worldwide. In recent years, Phragmites has attracted attention for its potential use as roughage. Given the increasing demand for feed and the number of constructed wetlands (CWs) vegetated with Phragmites, Phragmites is expected to play an important role in roughage production. Thus, it is vital to understand the effects of harvest timing and frequency on dry matter yield, nutritive value, and nitrogen (N) removal to establish appropriate vegetation management. In two CWs in Southwest China, four treatments with different harvesting frequencies were evaluated in monospecific areas of P. japonicus. The four treatments included no harvest, single harvest at 6 months, two harvests at 2 and 4 months, and three harvests at 2, 4, and 6 months. A sharp decline in the total digestible nutrients (TDN) concentration and the rate of increase in dry matter (DM) yield was associated with the heading timings, and the seasonal variations in TDN were likely influenced by carbohydrate accumulation in the stems. The three harvest treatment contributed to substantially improve the N and DM yields without decreasing the nutritive value but negatively affected the growth in the following year. Therefore, not only the combinations of harvest timing and frequency but also other management practices, including partial harvesting, may be needed to optimize CW performance and roughage production.

[Molecular cloning, bacterial expression analysis and functional characterization of pathogenesis-related PR10-2 gene in Panax notoginseng].

Base on the transcriptome analysis and RT-PCR techniques,a pathogenesis-related protein 10 gene was isolated from Panax notoginseng root and named as PnPR10-2. Bioinformatics and phylogenetic trees analysis revealed that open reading frame (ORF) of PnPR10-2 was 465 bp in length,encoding 154 amino acids,containing one typical conserved domain of pathogenesis related protein Bet v I family, and showed high similarity with that from P. ginseng. The recombinant expressed plasmid pET32a(+)-PnPR10-2 was expressed in Escherichia coli BL21. The expression conditions were optimized and it could be expressed well in soluble and inclusion body protein. Purified PnPR10-2 recombinant protein from the supernatant of cells was used to analysis the pathogen resistance activity by paper method. The purified recombinant protein could inhibit typical root rot disease pathogen (Fusarium solani and Cylindrocarpon destructans）growth evidently, we conjecture that PnPR10-2 may participated in defense response of P. notoginseng resistance to root rot disease pathogen.

Auxin enhances aluminium-induced citrate exudation through upregulation of GmMATE and activation of the plasma membrane H+-ATPase in soybean roots.

Background and Aims Aluminium (Al) toxicity is a limiting factor for plant growth and crop production in acidic soils. Citrate exudation and activation of the plasma membrane H+-ATPase are involved in soybean responses to Al stress. Auxin has crucial functions in plant growth and stress responses. However, little is known about possible interactions between auxin and citrate exudation under Al stress. In this study, we elucidated the regulatory roles of IAA in Al-induced citrate exudation in soybean roots. Methods We measured IAA content, Al concentration, citrate exudation, plasma membrane H+-ATPase activity, expression of the relevant genes and phosphorylation of the plasma membrane H+-ATPase by integrating physiological characterization and molecular analysis using hydroponically grown soybean. Key Results The concentration of IAA was increased by 25 and 50 µm Al, but decreased to the control level at 200 µm Al. External addition of 50 µm IAA to the root medium containing 25, 50 or 200 µm Al decreased root Al concentration and stimulated Al-induced citrate exudation and the plasma membrane H+-ATPase activity. Reverse transcription-PCR analysis showed that exogenous IAA enhanced the expression of citrate exudation transporter (GmMATE) but not the plasma membrane H+-ATPase gene. The western blot results suggested that IAA enhanced phosphorylation of the plasma membrane H+-ATPase under Al stress. Conclusions Auxin enhanced Al-induced citrate exudation through upregulation of GmMATE and an increase in phosphorylation of the plasma membrane H+-ATPase in soybean roots.

Phosphorylation and Interaction with the 14-3-3 Protein of the Plasma Membrane H+-ATPase are Involved in the Regulation of Magnesium-Mediated Increases in Aluminum-Induced Citrate Exudation in Broad Bean (Vicia faba. L).

Several studies have shown that external application of micromolar magnesium (Mg) can increase the resistance of legumes to aluminum (Al) stress by enhancing Al-induced citrate exudation. However, the exact mechanism underlying this regulation remains unknown. In this study, the physiological and molecular mechanisms by which Mg enhances Al-induced citrate exudation to alleviate Al toxicity were investigated in broad bean. Micromolar concentrations of Mg that alleviated Al toxicity paralleled the stimulation of Al-induced citrate exudation and increased the activity of the plasma membrane (PM) H(+)-ATPase. Northern blot analysis shows that a putative MATE-like gene (multidrug and toxic compound extrusion) was induced after treatment with Al for 4, 8 and 12 h, whereas the mRNA abundance of the MATE-like gene showed no significant difference between Al plus Mg and Al-only treatments during the entire treatment period. Real-time reverse transcription-PCR (RT-PCR) and Western blot analyses suggest that the transcription and translation of the PM H(+)-ATPase were induced by Al but not by Mg. In contrast, immunoprecipitation suggests that Mg enhanced the phosphorylation levels of VHA2 and its interaction with the vf14-3-3b protein under Al stress. Taken together, our results suggest that micromolar concentrations of Mg can alleviate the Al rhizotoxicity by increasing PM H(+)-ATPase activity and Al-induced citrate exudation in YD roots. This enhancement is likely to be attributable to Al-induced increases in the expression of the MATE-like gene and vha2 and Mg-induced changes in the phosphorylation levels of VHA2, thus changing its interaction with the vf14-3-3b protein.

Investigation of the role of the calvin cycle and C1 metabolism during HCHO metabolism in gaseous HCHO-treated petunia under light and dark conditions using 13C-NMR.

INTRODUCTION: It has been shown that formaldehyde (HCHO) absorbed by plants can be assimilated through the Calvin cycle or C1 metabolism. Our previous study indicated that Petunia hybrida could effectively eliminate HCHO from HCHO-polluted air. OBJECTIVE: To understand the roles of C1 metabolism and the Calvin cycle during HCHO metabolism and detoxification in petunia plants treated with gaseous H(13)CHO under light and dark conditions. METHODS: Aseptically grown petunia plants were treated with gaseous H(13)CHO under dark and light conditions. The metabolites generated from HCHO detoxification in petunia were investigated using (13)C-NMR. RESULTS: [2-(13)C]glycine (Gly) was generated via C1 metabolism and [U-(13)C]glucose (Gluc) was produced through the Calvin cycle simultaneously in petunia treated with low-level gaseous H(13)CHO under light conditions. Generation of [2-(13)C]Gly decreased whereas [U-(13) C]Gluc and [U-(13)C]fructose (Fruc) production increased greatly under high-level gaseous H(13)CHO stress in the light. In contrast, [U-(13)C]Gluc and [U-(13)C] Fruc production decreased greatly and [2-(13)C]Gly generation increased significantly under low-level and high-level gaseous H(13)CHO stress in the dark. CONCLUSION: C1 metabolism and the Calvin cycle contributed differently to HCHO metabolism and detoxification in gaseous H(13CHO-treated petunia plants. As the level of gaseous HCHO increased, the role of C1 metabolism decreased and the role of the Calvin cycle increased under light conditions. However, opposite changes were observed in petunia plants under dark conditions.

C1 metabolism and the Calvin cycle function simultaneously and independently during HCHO metabolism and detoxification in Arabidopsis thaliana treated with HCHO solutions.

Formaldehyde (HCHO) is suggested to be detoxified through one-carbon (C1) metabolism or assimilated by the Calvin cycle in plants. To further understand the function of the Calvin cycle and C1 metabolism in HCHO metabolism in plants, HCHO elimination and metabolism by Arabidopsis thaliana in HCHO solutions was investigated in this study. Results verified that Arabidopsis could completely eliminate aqueous HCHO from the HCHO solutions. Carbon-13 nuclear magnetic resonance ((13)C-NMR) analysis showed that H(13)CHO absorbed by Arabidopsis was first oxidized to H(13)COOH. Subsequently, a clear increase in [U-(13)C]Gluc peaks accompanied by a strong enhancement in peaks of [2-(13)C]Ser and [3-(13)C]Ser appeared in Arabidopsis. Pretreatment with cyclosporin A or L-carnitine, which might inhibit the transport of (13)C-enriched compounds into chloroplasts and mitochondria, caused a remarkable decline in yields of both [U-(13)C]Gluc and [3-(13)C]Ser in H(13)CHO-treated Arabidopsis. These results suggested that both the Calvin cycle and the C1 metabolism functioned simultaneously during HCHO detoxification. Moreover, both functioned more quickly under high H(13)CHO stress than low H(13)CHO stress. When a photorespiration mutant was treated in 6 mm H(13)CHO solution, formation of [U-(13)C]Gluc and [2-(13)C]Ser was completely inhibited, but generation of [3-(13)C]Ser was not significantly affected. This evidence suggested that the Calvin cycle and C1 metabolism functioned independently in Arabidopsis during HCHO metabolism.

Themoanaerobacterium calidifontis sp. nov., a novel anaerobic, thermophilic, ethanol-producing bacterium from hot springs in China.

A novel thermophilic Gram staining positive strain Rx1 was isolated from hot springs in Baoshan of Yunnan Province, China. The strain was characterized as a hemicellulose-decomposing obligate anaerobe bacterium that is rod-shaped (diameter: 0.5-0.7 µm; length: 2.0-6.7 µm), spore-forming, and motile. Its growth temperature range is 38-68 °C (optimum 50-55 °C) and pH range is 4.5-8.0 (optimum 7.0). The maximum tolerance concentration of NaCl was 3 %. Rx1 converted thiosulfate to elemental sulfur and reduced sulfite to hydrogen sulfide. The bacterium grew by utilizing xylan and starch, as well as a wide range of monosaccharide and polysaccharides, including glucose and xylose. The main products of fermentation were ethanol, lactate, acetate, CO2, and H2. The maximum xylanase activity in the culture supernatant after 30 h of incubation at 55 °C was 16.2 U/ml. Rx1 DNA G + C content was 36 mol %. 16S rRNA gene sequence analysis indicated that strain Rx1 belonged to the genus Thermoanaerobacterium of the family 'Thermoanaerobacteriaceae' (Firmicutes), with Thermoanaerobacterium aciditolerans 761-119 (99.2 % 16S rRNA gene sequence similarity) being its closest relative. DNA-DNA hybridization between Rx1 and T. aciditolerans 761-119 showed 36 % relatedness. Based on its physiological and biochemical tests and DNA-DNA hybridization analyses, the isolate is considered to represent a novel species in the genus Thermoanaerobacterium, for which the name Thermoanaerobacterium calidifontis sp. nov. is proposed, with the type strain is Rx1 (=JCM 18270 = CCTCC M 2011109).

Irrigation system and land use effect on surface water quality in river, at Lake Dianchi, Yunnan, China.

The surface water samples were collected in river Dahe and its tributaries, which flow into severely eutrophic lake Dianchi, Yunnan Province, China, in order to elucidate factors controlling water quality fluctuations. The temporal and spatial distribution of water quality tendency was observed. The water quality of each river is dependent on the hydrology effect such water gate and circulating irrigation system. We must consider the hydrology effect to accurately understand water quality variations of river in this study field. In river without highly circulating irrigation system or water gate effect, the downstream nitrate nitrogen (NO3-N) concentration increase occurred in area dominated by open field cultivation, whereas the NO3-N concentration was constant or decreased in area dominated by greenhouse land use. This result suggests that greenhouse covers the soil from precipitation, and nitrate load of greenhouse could be less than that of open field cultivation while the rainfall event. In the upper reaches of river, where is dominated by open field cultivation, there were no sharp increase dissolved molybdate reactive phosphorus and total phosphorus concentration, but P load was accumulated in the lower reaches of river, whose predominant land use is greenhouse. Although the P sources is unclear in this study, greenhouse area may have potential of P loads due to its high P content in greenhouse soil. Considering hydrology effect is necessary to determine what the major factor is influencing the water quality variation, especially in area with highly complicated irrigation system in this studying site.

Optimal discharge planning for esophagectomy patients with enhanced recovery after surgery: Recommendations.

Background: Studies have suggested that the postoperative length of stay (PLOS) of esophagectomy patients under the enhanced recovery after surgery (ERAS) pathway should be >10 days as against the previously recommended 7 days. We investigated the distribution and influencing factors of PLOS in the ERAS pathway in order to recommend an optimal planned discharge time. Methods: This was a single-center retrospective study of 449 patients with thoracic esophageal carcinoma who underwent esophagectomy and perioperative ERAS between January 2013 and April 2021. We established a database to prospectively document the causes of delayed discharge. Results: The mean and median PLOS were 10.2 days and 8.0 days (range: 5-97), respectively. Patients were divided into four groups: group A (PLOS ≤ 7 days), 179 patients (39.9%); group B (8 ≤ PLOS ≤ 10 days), 152 (33.9%); group C (11 ≤ PLOS ≤ 14 days), 68 (15.1%); group D (PLOS > 14 days), 50 patients (11.1%). The main cause of prolonged PLOS in group B was minor complications (prolonged chest drainage, pulmonary infection, recurrent laryngeal nerve injury). Severely prolonged PLOS in groups C and D were due to major complications and comorbidities. On multivariable logistic regression analysis, open surgery, surgical duration >240 min, age >64 years, surgical complication grade >2, and critical comorbidities were identified as risk factors for delayed discharge. Conclusions: The optimal planned discharge time for patients undergoing esophagectomy with ERAS should be 7-10 days with a 4-day discharge observation window. Patients at risk of delayed discharge should be managed adopting PLOS prediction.

14-3-3 proteins regulate the HCHO stress response by interacting with AtMDH1 and AtGS1 in tobacco and Arabidopsis.

Formaldehyde (HCHO) is one of the most essential common carcinogenic environmental pollutants. While 14-3-3 proteins are known to regulate the response of plants to HCHO stress, the regulatory mechanisms responsible for a tolerant phenotype remain unclear. We first performed qPCR analysis of HCHO-treated Arabidopsis and tobacco and determined that the expression of At14-3-3PSI and Nt14-3-3C genes was rapidly upregulated after HCHO stress. Furthermore, overexpression of 14-3-3, AtMDH1 or AtGS1 genes enhanced plant HCHO absorption capacity and resistance, and knockdown or knockout of 14-3-3, AtMDH1 or AtGS1 genes reduced plant HCHO absorption capacity and resistance. However, overexpression of the AtGS1 and AtMDH1 genes in the At14-3-3 psi mutant restored HCHO uptake and resistance in Arabidopsis. Moreover, 14-3-3 bound to the N-terminus of AtMDH1 and the C-terminus of AtGS1, respectively, and repressed and enhanced their expression. The 13C NMR results of HCHO stress mutants Atgs1 and Atmdh1 showed that the metabolites Glu and Asp rapidly increased, indicating that AtGS1 and AtMDH1 were indeed indispensable for Arabidopsis to metabolize HCHO. In conclusion, we uncovered a HCHO stress response mechanism mediated by 14-3-3, which enhances the plant's ability to absorb HCHO, deepening our understanding of how plants respond to HCHO stress.

Overexpression of tomato glutathione reductase (SlGR) in transgenic tobacco enhances salt tolerance involving the S-nitrosylation of GR.

S-nitrosylation, a post-translational modification (PTM) dependent on nitric oxide, is essential for plant development and environmental responsiveness. However, the function of S-nitrosylation of glutathione reductase (GR) in tomato (SlGR) under NaCl stress is yet uncertain. In this study, sodium nitroprusside (SNP), an exogenous NO donor, alleviated the growth inhibition of tomato under NaCl treatment, particularly at 100 µM. Following NaCl treatment, the transcripts, enzyme activity, and S-nitrosylated level of GR were increased. In vitro, the SlGR protein was able to be S-nitrosylated by S-nitrosoglutathione (GSNO), significantly increasing the activity of GR. SlGR overexpression transgenic tobacco plants exhibited enhanced germination rate, fresh weight, and increased root length in comparison to wild-type (WT) seedlings. The accumulation of reactive oxygen species (ROS) was lower, whereas the expression and activities of GR, ascorbate peroxidase (APX), superoxide dismutase (SOD), and catalase (CAT); the ratio of ascorbic acid/dehydroascorbic acid (AsA/DHA), reduced glutathione/oxidized glutathione (GSH/GSSG), total soluble sugar and proline contents; and the expression of stress-related genes were higher in SlGR overexpression transgenic plants in comparison to the WT plants following NaCl treatment. The accumulation of NO and S-nitrosylated levels of GR in transgenic plants was higher in comparison to WT plants following NaCl treatment. These results indicated that S-nitrosylation of GR played a significant role in salt tolerance by regulating the oxidative state.