CsBPC2 is essential for cucumber survival under cold stress.

Cold stress affects the growth and development of cucumbers. Whether the BPC2 transcription factor participates in cold tolerance and its regulatory mechanism in plants have not been reported. Here, we used wild-type (WT) cucumber seedlings and two mutant Csbpc2 lines as materials. The underlying mechanisms were studied by determining the phenotype, physiological and biochemical indicators, and transcriptome after cold stress. The results showed that CsBPC2 knockout reduced cucumber cold tolerance by increasing the chilling injury index, relative electrical conductivity and malondialdehyde (MDA) content and decreasing antioxidant enzyme activity. We then conducted RNA sequencing (RNA-seq) to explore transcript-level changes in Csbpc2 mutants. A large number of differentially expressed genes (1032) were identified and found to be unique in Csbpc2 mutants. However, only 489 down-regulated genes related to the synthesis and transport of amino acids and vitamins were found to be enriched through GO analysis. Moreover, both RNA-seq and qPT-PCR techniques revealed that CsBPC2 knockout also decreased the expression of some key cold-responsive genes, such as CsICE1, CsCOR413IM2, CsBZR1 and CsBZR2. These results strongly suggested that CsBPC2 knockout not only affected cold function genes but also decreased the levels of some key metabolites under cold stress. In conclusion, this study reveals for the first time that CsBPC2 is essential for cold tolerance in cucumber and provides a reference for research on the biological function of BPC2 in other plants.

CsBPC2 is a key regulator of root growth and development.

BASIC PENTACYSTEINE (BPCs) transcription factors are important regulators of plant growth and development. However, the regulatory mechanism of BPC2 in roots remains unclear. In our previous study, we created Csbpc2 cucumber mutants by the CRISPR/Cas9 system, and our studies on the phenotype of Csbpc2 mutants showed that the root growth was inhibited compared with wide-type (WT). Moreover, the surface area, volume and number of roots decreased significantly, with root system architecture changing from dichotomous branching to herringbone branching. Compared with WT, the leaf growth of the Csbpc2 mutants was not affected. However, the palisade and spongy tissue were significantly thinner, which was not beneficial for photosynthesis. The metabolome of root exudates showed that compared with WT, amino acids and their derivatives were significantly decreased, and the enriched pathways were mainly regulated by amino acids and their derivatives, indicating that knockout of CsBPC2 mainly affected the amino acid content in root exudates. Importantly, transcriptome analysis showed that knockout of CsBPC2 mainly affected root gene expression. Knockout of CsBPC2 significantly reduced the gene expression of gibberellins synthesis. However, the expression of genes related to amino acid synthesis, nitrogen fixation and PSII-related photosynthesis increased significantly, which may be due to the effect of knocking out CsBPC2 on gibberellins synthesis, resulting in the inhibition of seedling growth, thus forming negative feedback regulation. Generally, we showed for the first time that BPC2 is a key regulator gene of root growth and development, laying the foundation for future mechanisms of BPC2 regulation in roots.

Long non-coding RNA KCNQ1OT1 promotes the progression of gastric cancer via the miR-145-5p/ARF6 axis.

BACKGROUND: Long non-coding RNA KCNQ1 opposite strand/antisense transcript one gene (KCNQ1OT1) has been reported to be involved in the progression of many types of human cancer, whereas its role in gastric cancer (GC) remains unknown. The present study aimed to investigate the role of KCNQ1OT1 in GC. METHODS: In total, 25 GC tissues and adjacent normal tissues were collected. The expression of KCNQ1OT1, miR-145-5p and ARF6 in GC tissues and cell lines was detected by quantitative reverse transcriptase-polymerase chain reaction or western blotting. Bioinformatics analysis and a dual luciferase reporter assay were performed to determine the relationship between KCNQ1OT1 and miR-145-5p or miR-145-5p and ARF6. Gain- and loss-of function of KCNQ1OT1 and miR-145-5p were achieved to confirm their roles in GC cells. Cell counting kit-8, colony formation and flow cytometry assays were used to evaluate cell viability, proliferation and apoptosis. A xenograft tumor model was established with BGC803 tumor cells transfected with sh-KCNQ1OT1 or empty vector to determine the role of LINC01089 in vivo. RESULTS: The expression levels of KCNQ1OT1 were markedly elevated in GC tissues and cells. Knockdown of KCNQ1OT1 inhibited GC tumor growth, reduced GC cell viability and colony formation, and induced GC cell apoptosis. The expression levels of miR-145-5p were significantly decreased in GC cells and correlated with the expression of KCNQ1OT1 in GC tumors. Moreover, KCNQ1OT1 directly binds with miR-145-5p, which is targeting ARF6. Knockdown of KCNQ1OT1 increased the expression levels of miR-145-5p. Inhibition of miR-145-5p increased the expression levels of KCNQ1OT1 and also attenuated the effects of knockdown of KCNQ1OT1 on the viability, proliferation and apoptosis of GC cells. In addition, overexpression of miR-145-5p reduced GC cell viability and colony formation and induced GC cell apoptosis, whereas overexpression of ARF6 attenuated the effects of overexpression of miR-145-5p on GC cell viability, colony formation and apoptosis. CONCLUSIONS: KCNQ1OT1 can promote GC progression through the miR-145-5p/ARF6 axis. KCNQ1OT1 may serve as a therapeutic target and a diagnostic biomarker of GC.

Adaptation of cucumber seedlings to low temperature stress by reducing nitrate to ammonium during it's transportation.

BACKGROUND: Low temperature severely depresses the uptake, translocation from the root to the shoot, and metabolism of nitrate and ammonium in thermophilic plants such as cucumber (Cucumis sativus). Plant growth is inhibited accordingly. However, the availability of information on the effects of low temperature on nitrogen transport remains limited. RESULTS: Using non-invasive micro-test technology, the net nitrate (NO3-) and ammonium (NH4+) fluxes in the root hair zone and vascular bundles of the primary root, stem, petiole, midrib, lateral vein, and shoot tip of cucumber seedlings under normal temperature (NT; 26 °C) and low temperature (LT; 8 °C) treatment were analyzed. Under LT treatment, the net NO3- flux rate in the root hair zone and vascular bundles of cucumber seedlings decreased, whereas the net NH4+ flux rate in vascular bundles of the midrib, lateral vein, and shoot tip increased. Accordingly, the relative expression of CsNRT1.4a in the petiole and midrib was down-regulated, whereas the expression of CsAMT1.2a-1.2c in the midrib was up-regulated. The results of 15N isotope tracing showed that NO3--N and NH4+-N uptake of the seedlings under LT treatment decreased significantly compared with that under NT treatment, and the concentration and proportion of both NO3--N and NH4+-N distributed in the shoot decreased. Under LT treatment, the actual nitrate reductase activity (NRAact) in the root did not change significantly, whereas NRAact in the stem and petiole increased by 113.2 and 96.2%, respectively. CONCLUSIONS: The higher net NH4+ flux rate in leaves and young tissues may reflect the higher NRAact in the stem and petiole, which may result in a higher proportion of NO3- being reduced to NH4+ during the upward transportation of NO3-. The results contribute to an improved understanding of the mechanism of changes in nitrate transportation in plants in response to low-temperature stress.

Activation of the LINC00242/miR-141/FOXC1 axis underpins the development of gastric cancer.

BACKGROUND: Long non-coding RNAs (LncRNAs) are a class of newly identified transcripts recognized as critical governors of gene expression during human carcinogenesis, whereas their tumor-suppressive or tumor-promoting effects on gastric cancer (GC) are required for further investigation. In the study, we identify the expression pattern of a novel lncRNA LINC00242 in GC and its possible permissive role in the development of GC. METHODS: The study included 68 pairs of GC and adjacent normal gastric tissue samples. The viability, migration, and invasion of cultured human GC cells HGC27 were evaluated by CCK-8 and Transwell chamber assays. In vitro tube formation of human brain microvascular endothelial cells (HBMVECs) in HGC27 cell coculture was detected. The regulatory network of LINC00242/miR-141/FOXC1 was verified using dual luciferase reporter gene assay and RNA immunoprecipitation (RIP) assay. Subcutaneous xenografts of HGC27 cells were performed in nude mice. RESULTS: LINC00242 was highly expressed in GC tissues and cells and contributed to poor prognosis. LINC00242 knockdown inhibited HGC27 cell viability, migration and invasion, and tube formation of HBMVECs. LINC00242 interacted with miR-141 and positively regulated FOXC1, a target gene of miR-141. LINC00242 knockdown was partially lost in HGC27 cells upon miR-141 inhibition or FOXC1 overexpression. The tumor-promoting effect of LINC00242 on GC was demonstrated in nude mice. CONCLUSION: Taken together, the present study demonstrates the oncogenic role of the LINC00242/miR-141/FOXC1 axis in GC, highlighting a theoretical basis for GC treatment.

The CsGPA1-CsAQPs module is essential for salt tolerance of cucumber seedlings.

KEY MESSAGE: CsGPA1 interacts with CsTIP1.1 (a member of CsAQPs) and suppression of CsGPA1 results the reverse expression of CsAQPs in leaves and roots, resulting in declining water content of cucumber seedlings under salt stress. Salt stress seriously affects cucumber growth and development. Whether the G-protein alpha subunit functions in cucumber during salt stress and its regulation mechanism remains unknown. We interrogated CsGPA1-RNAi lines to identify the role of CsGPA1 during salt stress. Phenotypically, compared with wild type, leaves were severely withered, and root cells showed signs of senescence under salt stress for RNAi lines. Compared with WT, SOD and CAT activity, soluble protein and proline contents all decreased in RNAi lines, while malondialdehyde and relative electrical conductivity increased. Through screening the yeast two-hybrid library and combined with yeast two-hybrid and GST pull-down, the interaction of CsGPA1 with CsTIP1.1 was found the first time in a plant. Then, the expression of aquaporin (AQP) family genes was detected. The expression of CsAQP genes in leaves and roots was primarily up-regulated in WT under salt stress. However, interference by CsGPA1 resulted in enhanced expression of CsAQPs except for CsTIP3.2 in leaves, but reduced expression of some CsAQPs in roots under salt stress. Furthermore, principal component analysis of CsAQP expression profiles and linear regression analysis between CsGPA1 and CsAQPs revealed that CsGPA1 reversely regulated the expression of CsAQPs in leaves and roots under salt stress. Moreover, the water content in leaves and roots of RNAi seedlings significantly decreased compared with WT under salt stress. Overall, CsGPA1 interacts with CsTIP1.1 and suppression of CsGPA1 results in opposite patterns of expression of CsAQPs in leaves and roots, resulting in declining water content of cucumber under salt stress.

Correction to: 24-Epibrassinolide promotes NO3- and NH4+ ion flux rate and NRT1 gene expression in cucumber under suboptimal root zone temperature.

In the original publication of this article [1], the author pointed out there is an error in Figs. 4 and 5.

24-Epibrassinolide promotes NO3- and NH4+ ion flux rate and NRT1 gene expression in cucumber under suboptimal root zone temperature.

BACKGROUND: Suboptimal root zone temperature (RZT) causes a remarkable reduction in growth of horticultural crops during winter cultivation under greenhouse production. However, limited information is available on the effects of suboptimal RZT on nitrogen (N) metabolism in cucumber seedlings. The aim of this study is to investigate the effects of 24-Epibrassinolide (EBR) on nitrate and ammonium flux rate, N metabolism, and transcript levels of NRT1 family genes under suboptimal RZT in cucumber seedlings. RESULTS: Suboptimal RZT (LT) negatively affected on cucumber growth and proportionately decreased EBR contents, bleeding rate, root activity, enzyme activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT), nitrate (NO3-) influx rate, ammonium (NH4+) efflux rate, and transcript levels of nitrate transporter (NRT1) encoding genes. However, exogenous EBR reduced the harmful effects of suboptimal RZT and increased endogenous EBR contents, bleeding rate, root activity, enzyme activities of NR, NiR, GS, and GOGAT, NH4+ and NO3- flux rates and contents, and N accumulation. EBR-treated seedlings also upregulated the transcript levels of nitrate transporters CsNRT1.1, CsNRT1.2A, CsNRT1.2B, CsNRT1.2C, CsNRT1.3, CsNRT1.4A, CsNRT1.5B, CsNRT1.5C, CsNRT1.9, and CsNRT1.10, and downregulated CsNRT1.5A and CsNRT1.8. LT treatment upregulated the expression level of CsNRT1.5A, while exogenous BZR application downregulated the expression level of NRT1 genes. CONCLUSION: These results indicate that exogenous application of EBR alleviated the harmful effects of suboptimal RZT through changes in N metabolism, NH4+ and NO3- flux rates, and NRT1 gene expression, leading to improved cucumber seedlings growth. Our study provides the first evidence of the role of EBR in the response to suboptimal RZT in cucumber, and can be used to improve vegetable production.

Integrated Metabolome and Transcriptome Analysis Provide Insights into the Effects of Grafting on Fruit Flavor of Cucumber with Different Rootstocks.

Rootstocks frequently exert detrimental effects on the fruit quality of grafted cucumber (Cucumis sativus L.) plants. To understand and ultimately correct this deficiency, a transcriptomic and metabolomic comparative analysis was performed among cucumber fruits from non-grafted plants (NG), and fruits from plants grafted onto different rootstocks of No.96 and No.45 (Cucurbita moschata. Duch), known to confer a different aroma and taste. We found remarkable changes in the primary metabolites of sugars, organic acids, amino acids, and alcohols in the fruit of the grafted cucumber plants with different rootstocks, compared to the non-grafted ones, especially No.45. We identified 140, 131, and 244 differentially expressed genes (DEGs) in the comparisons of GNo.96 vs. NG, GNo.45 vs. NG, and GNo.45 vs. GNo.96. The identified DEGs have functions involved in many metabolic processes, such as starch and sucrose metabolism; the biosynthesis of diterpenoid, carotenoid, and zeatin compounds; and plant hormone signal transduction. Members of the HSF, AP2/ERF-ERF, HB-HD-ZIP, and MYB transcription factor families were triggered in the grafted cucumbers, especially in the cucumber grafted on No.96. Based on a correlation analysis of the relationships between the metabolites and genes, we screened 10 candidate genes likely to be involved in sugar metabolism (Fructose-6-phosphate and trehalose), linoleic acid, and amino-acid (isoleucine, proline, and valine) biosynthesis in grafted cucumbers, and then confirmed the gene expression patterns of these genes by qRT-PCR. The levels of TPS15 (Csa3G040850) were remarkably increased in cucumber fruit with No.96 rootstock compared with No.45, suggesting changes in the volatile chemical production. Together, the results of this study improve our understanding of flavor changes in grafted cucumbers, and identify the candidate genes involved in this process.

Genome-Wide Identification and Characterization of Cucumber BPC Transcription Factors and Their Responses to Abiotic Stresses and Exogenous Phytohormones.

BASIC PENTACYSTEINE (BPC) is a small transcription factor family that functions in diverse growth and development processes in plants. However, the roles of BPCs in plants, especially cucumber (Cucumis sativus L.), in response to abiotic stress and exogenous phytohormones are still unclear. Here, we identified four BPC genes in the cucumber genome, and classified them into two groups according to phylogenetic analysis. We also investigated the gene structures and detected five conserved motifs in these CsBPCs. Tissue expression pattern analysis revealed that the four CsBPCs were expressed ubiquitously in both vegetative and reproductive organs. Additionally, the transcriptional levels of the four CsBPCs were induced by various abiotic stress and hormone treatments. Overexpression of CsBPC2 in tobacco (Nicotiana tabacum) inhibited seed germination under saline, polyethylene glycol, and abscisic acid (ABA) conditions. The results suggest that the CsBPC genes may play crucial roles in cucumber growth and development, as well as responses to abiotic stresses and plant hormones. CsBPC2 overexpression in tobacco negatively affected seed germination under hyperosmotic conditions. Additionally, CsBPC2 functioned in ABA-inhibited seed germination and hypersensitivity to ABA-mediated responses. Our results provide fundamental information for further research on the biological functions of BPCs in development and abiotic stress responses in cucumber and other plant species.

The physiological and molecular mechanism of brassinosteroid in response to stress: a review.

The negative effects of environmental stresses, such as low temperature, high temperature, salinity, drought, heavy metal stress, and biotic stress significantly decrease crop productivity. Plant hormones are currently being used to induce stress tolerance in a variety of plants. Brassinosteroids (commonly known as BR) are a group of phytohormones that regulate a wide range of biological processes that lead to tolerance of various stresses in plants. BR stimulate BRASSINAZOLE RESISTANCE 1 (BZR1)/BRI1-EMS SUPPRESSOR 1 (BES1), transcription factors that activate thousands of BR-targeted genes. BR regulate antioxidant enzyme activities, chlorophyll contents, photosynthetic capacity, and carbohydrate metabolism to increase plant growth under stress. Mutants with BR defects have shortened root and shoot developments. Exogenous BR application increases the biosynthesis of endogenous hormones such as indole-3-acetic acid, abscisic acid, jasmonic acid, zeatin riboside, brassinosteroids (BR), and isopentenyl adenosine, and gibberellin (GA) and regulates signal transduction pathways to stimulate stress tolerance. This review will describe advancements in knowledge of BR and their roles in response to different stress conditions in plants.

5-Aminolevulinic Acid Improves Nutrient Uptake and Endogenous Hormone Accumulation, Enhancing Low-Temperature Stress Tolerance in Cucumbers.

5-aminolevulinic acid (ALA) increases plant tolerance to low-temperature stress, but the physiological and biochemical mechanisms that underlie its effects are not fully understood. To investigate them, cucumber seedlings were treated with different ALA concentrations (0, 15, 30 and 45 mg/L ALA) and subjected to low temperatures (12/8 °C day/night temperature). The another group (RT; regular temperature) was exposed to normal temperature (28/18 °C day/night temperature). Low-temperature stress decreased plant height, root length, leaf area, dry mass accumulation and the strong seedling index (SSI), chlorophyll contents, photosynthesis, leaf and root nutrient contents, antioxidant enzymatic activities, and hormone accumulation. Exogenous ALA application significantly alleviated the inhibition of seedling growth and increased plant height, root length, hypocotyl diameter, leaf area, and dry mass accumulation under low-temperature stress. Moreover, ALA increased chlorophyll content (Chl a, Chl b, Chl a+b, and Carotenoids) and photosynthetic capacity, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as the activities of superoxide dismutase (SOD), peroxidase (POD, catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) enzymes, while decreasing hydrogen peroxide (H2O2), superoxide (O2•-), and malondialdehyde (MDA) contents under low-temperature stress. In addition, nutrient contents (N, P, K, Mg, Ca, Cu, Fe, Mn, and Zn) and endogenous hormones (JA, IAA, BR, iPA, and ZR) were enhanced in roots and leaves, and GA4 and ABA were decreased. Our results suggest the up-regulation of antioxidant enzyme activities, nutrient contents, and hormone accumulation with the application of ALA increases tolerance to low-temperature stress, leading to improved cucumber seedling performance.

24-Epibrassinolide Ameliorates Endogenous Hormone Levels to Enhance Low-Temperature Stress Tolerance in Cucumber Seedlings.

Phytohormone biosynthesis and accumulation are essential for plant growth and development and stress responses. Here, we investigated the effects of 24-epibrassinolide (EBR) on physiological and biochemical mechanisms in cucumber leaves under low-temperature stress. The cucumber seedlings were exposed to treatments as follows: NT (normal temperature, 26 °C/18 °C day/night), and three low-temperature (12 °C/8 °C day/night) treatments: CK (low-temperature stress); EBR (low-temperature and 0.1 µM EBR); and BZR (low-temperature and 4 µM BZR, a specific EBR biosynthesis inhibitor). The results indicated that low-temperature stress proportionately decreased cucumber seedling growth and the strong seedling index, chlorophyll (Chl) content, photosynthetic capacity, and antioxidant enzyme activities, while increasing reactive oxygen species (ROS) and malondialdehyde (MDA) contents, hormone levels, and EBR biosynthesis gene expression level. However, EBR treatments significantly enhanced cucumber seedling growth and the strong seedling index, chlorophyll content, photosynthetic capacity, activities of antioxidant enzymes, the cell membrane stability, and endogenous hormones, and upregulated EBR biosynthesis gene expression level, while decreasing ROS and the MDA content. Based on these results, it can be concluded that exogenous EBR regulates endogenous hormones by activating at the transcript level EBR biosynthetic genes, which increases antioxidant enzyme capacity levels and reduces the overproduction of ROS and MDA, protecting chlorophyll and photosynthetic machinery, thus improving cucumber seedling growth.

Grafting-responsive miRNAs in cucumber and pumpkin seedlings identified by high-throughput sequencing at whole genome level.

Grafting is an important agricultural technique widely used for improving growth, yields and tolerance of crops to abiotic and biotic stresses. As one type of endogenous, non-coding small RNAs, microRNAs (miRNAs) regulate development and responsiveness to biotic and abiotic stresses by negatively mediating expression of target genes at the post-transcriptional level. However, there have been few detailed studies to evaluate the role of miRNAs in mediation of grafting-induced physiological processes in plants. Cucumis sativus and Cucurbita moschata are important vegetables worldwide. We constructed eight small RNA libraries from leaves and roots of seedlings that were grafted in the following four ways: (1) hetero-grafting, using cucumber as scion and pumpkin as rootstock; (2) hetero-grafting, with pumpkin as scion and cucumber as rootstock; (3) auto-grafting of cucumbers and (4) auto-grafting of pumpkins. High-throughput sequencing was employed, and more than 120 million raw reads were obtained. We annotated 112 known miRNAs belonging to 40 miRNA families and identified 48 new miRNAs in the eight libraries, and the targets of these known and novel miRNAs were predicted by bioinformatics. Grafting led to changes in expression of most miRNAs and their predicted target genes, suggesting that miRNAs may play significant roles in mediating physiological processes of grafted seedlings by regulating the expression of target genes. The potential role of the grafting-responsive miRNAs in seedling growth and long-distance transport of miRNA was discussed. These results are useful for functional characterization of miRNAs in mediation of grafting-dependent physiological processes.

Proteome and phosphoproteome analysis of 2,4-epibrassinolide-mediated cold stress response in cucumber seedlings.

The 2, 4-epibrassinolide (EBR) significantly increased plants cold tolerance. However, mechanisms of EBR in regulating cold tolerance in phosphoproteome and proteome levels have not been reported. The mechanism of EBR regulating cold response in cucumber was studied by multiple omics analysis. In this study, phosphoproteome analysis showed that cucumber responded to cold stress through multi-site serine phosphorylation, while EBR further upregulated single-site phosphorylation for most of cold-responsive phosphoproteins. Association analysis of the proteome and phosphoproteome revealed that EBR reprogrammed proteins in response to cold stress by negatively regulating protein phosphorylation and protein content, and phosphorylation negatively regulated protein content in cucumber. Further functional enrichment analysis of proteome and phosphoproteome showed that cucumber mainly upregulated phosphoproteins related to spliceosome, nucleotide binding and photosynthetic pathways in response to cold stress. However, different from the EBR regulation in omics level, hypergeometric analysis showed that EBR further upregulated 16 cold-up-responsive phosphoproteins participated photosynthetic and nucleotide binding pathways in response to cold stress, suggested their important function in cold tolerance. Analysis of cold-responsive transcription factors (TFs) by correlation between proteome and phosphoproteome showed that cucumber regulated eight class TFs may through protein phosphorylation under cold stress. Further combined with cold-related transcriptome found that cucumber phosphorylated eight class TFs, and mainly through targeting major hormone signal genes by bZIP TFs in response to cold stress, while EBR further increased these bZIP TFs (CsABI5.2 and CsABI5.5) phosphorylation level. In conclusion, the EBR mediated schematic of molecule response mechanisms in cucumber under cold stress was proposed.

Multifaceted regulatory functions of CsBPC2 in cucumber under salt stress conditions.

BASIC PENTACYSTEINE (BPC) transcription factors are essential regulators of plant growth and development. However, BPC functions and the related molecular mechanisms during cucumber (Cucumis sativus L.) responses to abiotic stresses, especially salt stress, remain unknown. We previously determined that salt stress induces CsBPC expression in cucumber. In this study, Csbpc2 transgene-free cucumber plants were created using a CRISPR/Cas9-mediated editing system to explore CsBPC functions associated with the salt stress response. The Csbpc2 mutants had a hypersensitive phenotype, with increased leaf chlorosis, decreased biomass, and increased malondialdehyde and electrolytic leakage levels under salt stress conditions. Additionally, a mutated CsBPC2 resulted in decreased proline and soluble sugar contents and antioxidant enzyme activities, which led to the accumulation of hydrogen peroxide and superoxide radicals. Furthermore, the mutation to CsBPC2 inhibited salinity-induced PM-H+-ATPase and V-H+-ATPase activities, resulting in decreased Na+ efflux and increased K+ efflux. These findings suggest that CsBPC2 may mediate plant salt stress resistance through its effects on osmoregulation, reactive oxygen species scavenging, and ion homeostasis-related regulatory pathways. However, CsBPC2 also affected ABA signaling. The mutation to CsBPC2 adversely affected salt-induced ABA biosynthesis and the expression of ABA signaling-related genes. Our results indicate that CsBPC2 may enhance the cucumber response to salt stress. It may also function as an important regulator of ABA biosynthesis and signal transduction. These findings will enrich our understanding of the biological functions of BPCs, especially their roles in abiotic stress responses, thereby providing the theoretical basis for improving crop salt tolerance.

PBAT/PLA humic acid biodegradable film applied on solar greenhouse tomato plants increased lycopene and decreased total acid contents.

This work aims to resolve residual film pollution in farmlands and improve tomato quality. The mechanical properties and degradation of PBAT/PLA lignin (MZS) and PBAT/PLA humic acid (FZS) composite biodegradable film were analyzed, and its effect on soil temperature and humidity, soil microorganisms, soil physical and chemical properties, tomato yield, and quality was studied. Polyethylene film (PE) was used as a control. The results demonstrate a higher degradation degree of FZS film than of MZS film. The degradation degree of FZS and MZS films reached level 2 and level 1, respectively, after 131 days of film covering. The weight loss rate of FZS and MZS films reached 52.74 % and 57.82 %, respectively, when buried for 160 days. Compared to the coverings of PE and MZS films, FZS film could significantly increase the soil's electric conductivity and organic matter content (p < 0.05). The relative abundance of soil fungi Chaetomium also increased. The yield, soluble solids, vitamin C (Vc), soluble sugar, and lycopene of tomato plants covered with FZS film significantly increased by 6.74 %, 8.75 %, 15.41 %, 8.30 %, and 27.27 % compared to plants covered with PE film, and the total acid and hardness significantly decreased by 24.95 % and 8.46 %, respectively (p < 0.05). Using 10 µm PBAT/PLA humic acid biodegradable film for tomato cultivation in autumn and winter increased the lycopene and decreased the total acid content by changing the soil's physical and chemical characteristics and increasing the content of Chaetomium soil.

Exploration of a Novel Prognostic Nomogram and Diagnostic Biomarkers Based on the Activity Variations of Hallmark Gene Sets in Hepatocellular Carcinoma.

Background: The initiation and progression of tumors were due to variations of gene sets rather than individual genes. This study aimed to identify novel biomarkers based on gene set variation analysis (GSVA) in hepatocellular carcinoma. Methods: The activities of 50 hallmark pathways were scored in three microarray datasets with paired samples with GSVA, and differential analysis was performed with the limma R package. Unsupervised clustering was conducted to determine subtypes with the ConsensusClusterPlus R package in the TCGA-LIHC (n = 329) and LIRI-JP (n = 232) cohorts. Differentially expressed genes among subtypes were identified as initial variables. Then, we used TCGA-LIHC as the training set and LIRI-JP as the validation set. A six-gene model calculating the risk scores of patients was integrated with the least absolute shrinkage and selection operator (LASSO) and stepwise regression analyses. Kaplan-Meier (KM) and receiver operating characteristic (ROC) curves were performed to assess predictive performances. Multivariate Cox regression analyses were implemented to select independent prognostic factors, and a prognostic nomogram was integrated. Moreover, the diagnostic values of six genes were explored with the ROC curves and immunohistochemistry. Results: Patients could be separated into two subtypes with different prognoses in both cohorts based on the identified differential hallmark pathways. Six prognostic genes (ASF1A, CENPA, LDHA, PSMB2, SRPRB, UCK2) were included in the risk score signature, which was demonstrated to be an independent prognostic factor. A nomogram including 540 patients was further integrated and well-calibrated. ROC analyses in the five cohorts and immunohistochemistry experiments in solid tissues indicated that CENPA and UCK2 exhibited high and robust diagnostic values. Conclusions: Our study explored a promising prognostic nomogram and diagnostic biomarkers in hepatocellular carcinoma.

Photosynthesis Mediated by RBOH-Dependent Signaling Is Essential for Cold Stress Memory.

Cold tolerance is improved by cold stress acclimation (CS-ACC), and the cold tolerance level is 'remembered' by plants. However, the underlying signaling mechanisms remain largely unknown. Here, the CS memory mechanism was studied by bioinformation, plant physiological and photosynthetic parameters, and gene expression. We found that CS-ACC induced the acquisition of CS memory and enhanced the maintenance of acquired cold tolerance (MACT) in cucumber seedlings. The H2O2 content and NADPH oxidase activity encoded by CsRBOH was maintained at higher levels during recovery after CS-ACC and inhibition of RBOH-dependent signaling after CS-ACC resulted in a decrease in the H2O2 content, NADPH oxidase activity, and MACT. CsRBOH2, 3, 4, and 5 showed high expression during recovery after CS-ACC. Many BZR-binding sites were identified in memory-responsive CsRBOHs promoters, and CsBZR1 and 3 showed high expression during recovery after CS-ACC. Inhibition of RBOH-dependent signaling or brassinosteroids affected the maintenance of the expression of these memory-responsive CsRBOHs and CsBZRs. The photosynthetic efficiency (PE) decreased but then increased with the prolonged recovery after CS-ACC, and was higher than the control at 48 h of recovery; however, inhibition of RBOH-dependent signaling resulted in a lower PE. Further etiolated seedlings experiments showed that a photosynthetic capacity was necessary for CS memory. Therefore, photosynthesis mediated by RBOH-dependent signaling is essential for CS memory.