EMG-based Multi-User Hand Gesture Classification via Unsupervised Transfer Learning Using Unknown Calibration Gestures.

The poor generalization performance and heavy training burden of the gesture classification model contribute as two main barriers that hinder the commercialization of sEMG-based human-machine interaction (HMI) systems. To overcome these challenges, eight unsupervised transfer learning (TL) algorithms developed on the basis of convolutional neural networks (CNNs) were explored and compared on a dataset consisting of 10 gestures from 35 subjects. The highest classification accuracy obtained by CORrelation Alignment (CORAL) reaches more than 90%, which is 10% higher than the methods without using TL. In addition, the proposed model outperforms 4 common traditional classifiers (KNN, LDA, SVM, and Random Forest) using the minimal calibration data (two repeated trials for each gesture). The results also demonstrate the model has a great transfer robustness/flexibility for cross-gesture and cross-day scenarios, with an accuracy of 87.94% achieved using calibration gestures that are different with model training, and an accuracy of 84.26% achieved using calibration data collected on a different day, respectively. As the outcomes confirm, the proposed CNN TL method provides a practical solution for freeing new users from the complicated acquisition paradigm in the calibration process before using sEMG-based HMI systems.

A novel zinc finger transcription factor, BcMsn2, is involved in growth, development, and virulence in Botrytis cinerea.

Reactive oxygen species (ROS) are important for plant defense against fungal attack. As a necrotrophic fungus, Botrytis cinerea can exploit ROS that originated from both sides of the host and pathogen during interaction to facilitate its infestation. Meanwhile, B. cinerea needs to exert an efficient oxidative stress responsive system to balance the intracellular redox state when encountering deleterious ROS levels. However, the machinery applied by B. cinerea to cope with ROS remains obscure. Herein, we investigated the role of the transcription factor BcMsn2 in regulating B. cinerea redox homeostasis. Disruption of the BcMsn2 gene severely impaired vegetative growth, sclerotium formation, conidial yield, and fungal virulence. The intracellular oxidative homeostasis of the ∆bcmsn2 mutant was disrupted, leading to significantly elevated levels of ROS and reduced activities of enzymes closely associated with oxygen stress, such as catalase (CAT) and superoxide dismutase (SOD). RNA-Seq and qRT-PCR analyses showed remarkable downregulation of the expression of several genes encoding ROS scavenging factors involved in maintaining the redox homeostasis in ∆bcmsn2, suggesting that BcMsn2 functions as a transcriptional regulator of these genes. Our findings indicated that BcMsn2 plays an indispensable role in maintaining the equilibrium of the redox state in B. cinerea, and intracellular ROS serve as signaling molecules that regulate the growth, asexual reproduction, and virulence of this pathogen.

The antifungal potential of the chelating agent EDTA against postharvest plant pathogen Botrytis cinerea.

Botrytis cinerea is a phytopathogenic fungus that causes gray mold, a major postharvest disease of fruits and vegetables. Chemical fungicides remain the main solution to control Botrytis disease, but concerns have raised about their safety to environment and human health, and there is an increasing need for development of more effective and less toxic treatments. In this study the divalent cation chelating agent ethylenediaminetetraacetic acid (EDTA) exhibited marked antifungal activity against B. cinerea, including inhibition of spore germination, mycelial growth, infection cushion formation, stimulation of cell death, and impairment of fungal virulence. These adverse effects of EDTA could be reversed by the addition of calcium ion, implying that metal ion chelation is involved in the fungicidal mechanism. Bean leaf and tomato fruit protection assay indicated that EDTA treatment led to a significant reduction of infection by B. cinerea. Furthermore, the antifungal activity of EDTA was significantly enhanced when used in combination with fenhexamid. These findings suggest that EDTA could be a promising tool to control B. cinerea, and application of EDTA may reduce the use of conventional chemical fungicides.

Botrytis cinerea Transcription Factor BcXyr1 Regulates (Hemi-)Cellulase Production and Fungal Virulence.

Botrytis cinerea is an agriculturally notorious plant-pathogenic fungus with a broad host range. During plant colonization, B. cinerea secretes a wide range of plant-cell-wall-degrading enzymes (PCWDEs) that help in macerating the plant tissue, but their role in pathogenicity has been unclear. Here, we report on the identification of a transcription factor, BcXyr1, that regulates the production of (hemi-)cellulases and is necessary for fungal virulence. Deletion of the bcxyr1 gene led to impaired spore germination and reduced fungal virulence and reactive oxygen species (ROS) production in planta. Secreted proteins collected from the bcxyr1 deletion strain displayed a weaker cell-death-inducing effect than the wild-type secretome when infiltrated to Nicotiana benthamiana leaves. Transcriptome sequencing (RNA-seq) analysis revealed 41 genes with reduced expression in the Δbcxyr1 mutant compared with those in the wild-type strain, of which half encode secreted proteins that are particularly enriched in carbohydrate-active enzyme (CAZyme)-encoding genes. Among them, we identified a novel putative expansin-like protein that was necessary for fungal virulence, supporting the involvement of BcXyr1 in the regulation of extracellular virulence factors. IMPORTANCE PCWDEs are considered important components of the virulence arsenal of necrotrophic plant pathogens. However, despite intensive research, the role of PCWDEs in the pathogenicity of necrotrophic phytopathogenic fungi remains ambiguous. Here, we demonstrate that the transcription factor BcXyr1 regulates the expression of a specific set of secreted PCWDE-encoding genes and that it is essential for fungal virulence. Furthermore, we identified a BcXyr1-regulated expansin-like gene that is required for fungal virulence. Our findings provide strong evidence for the importance of PCWDEs in the pathogenicity of B. cinerea and highlight specific PCWDEs that might be more important than others.

Lamin A/C-dependent chromatin architecture safeguards naïve pluripotency to prevent aberrant cardiovascular cell fate and function.

Tight control of cell fate choices is crucial for normal development. Here we show that lamin A/C plays a key role in chromatin organization in embryonic stem cells (ESCs), which safeguards naïve pluripotency and ensures proper cell fate choices during cardiogenesis. We report changes in chromatin compaction and localization of cardiac genes in Lmna-/- ESCs resulting in precocious activation of a transcriptional program promoting cardiomyocyte versus endothelial cell fate. This is accompanied by premature cardiomyocyte differentiation, cell cycle withdrawal and abnormal contractility. Gata4 is activated by lamin A/C loss and Gata4 silencing or haploinsufficiency rescues the aberrant cardiovascular cell fate choices induced by lamin A/C deficiency. We uncover divergent functions of lamin A/C in naïve pluripotent stem cells and cardiomyocytes, which have distinct contributions to the transcriptional alterations of patients with LMNA-associated cardiomyopathy. We conclude that disruption of lamin A/C-dependent chromatin architecture in ESCs is a primary event in LMNA loss-of-function cardiomyopathy.

Long noncoding RNA H19 suppresses cardiac hypertrophy through the MicroRNA-145-3p/SMAD4 axis.

Sustained cardiac hypertrophy (CH) contributes to many heart diseases. Long noncoding RNAs (lncRNAs) collectively play critical roles in cardiovascular diseases (CVDs). However, the roles of lncRNA H19 in CH are still unclear. A CH model was constructed utilizing isoproterenol (ISO). We demonstrated H19 could participate in regulating ISO-induced CH development both in vivo and in vitro. The online databases DIANA and TargetScan were used to predict the targets of H19 and MicroRNA-145-3p (miR-145-3p), respectively. Luciferase reporter assay was used to verify the downstream targets. The results showed that H19 was decreased under ISO stimulation. The H19 overexpression resulted in significant decrease in mouse heart size and weight, left ventricular systolic dysfunction, left ventricular posterior wall thickness and cardiac hypertrophic growth, while promoted the increase of left ventricular ejection fraction and left ventricle fraction shortening. H19 also inhibited protein expression levels of CH markers, such as atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and MYH7. Luciferase assays results showed that miR-145-3p was a target of H19 and SMAD4 was a target of miR-145-3p. We found that H19 regulated SMAD4 by sponging miR-145-3p. Knockout of miR-145-3p or overexpression of SMAD4 facilitated H19-induced decreases in ANP, BNP, and MYH7. Collectively, our findings have indicated that the H19/miR-145-3p/SMAD4 axis should be a negative regulator involved in CH progression.

Macrophage-Derived Exosomal Mir-155 Regulating Cardiomyocyte Pyroptosis and Hypertrophy in Uremic Cardiomyopathy.

miR-155 was synthesized and loaded into exosomes in increased infiltration of macrophages in a uremic heart. The released exosomal fusion with the plasma membrane leads to the release of miR-155 into the cytosol and translational repression of forkhead transcription factors of the O class (FoxO3a) in cardiomyocytes. Finally, macrophage-derived miR-155-containing exosomes promoted cardiomyocyte pyroptosis and uremic cardiomyopathy changes (cardiac hypertrophy and fibrosis) by directly targeting FoxO3a in uremic mice.

LncRNA FAF inhibits fibrosis induced by angiotensinogen II via the TGFß1-P-Smad2/3 signalling by targeting FGF9 in cardiac fibroblasts.

The dysregulation of Long noncoding RNAs (lncRNAs) has been implicated in many cardiovascular diseases, including cardiac fibrosis. However, the functions and mechanisms of lncRNAs in cardiac fibroblasts (CFs) have not been fully elucidated. First, we observed a correlation between cardiac remodeling (CR) and lncRNA FAF (FGF9-associated factor, termed FAF) expression in the heart. In vitro, we found that the expression of lncRNA FAF was altered in CFs, whereas it behaved inconsistently in cardiomyocytes (CMs). Next, we investigated the effects of lncRNA FAF on angiotensinogen II (Ang II)-induced cardiac fibrosis in neonatal rat CFs and explored the mechanism underlying these effects. In this study, lncRNA FAF was enriched in CFs and was associated with cardiac fibrosis. Upregulation of lncRNA FAF significantly restrained Ang II-induced increases in cell proliferation, differentiation and collagen accumulation of CFs. Moreover, we found that the function of lncRNA FAF was mainly realized through Transforming growth factor ß1 (TGFß1) secretion and then downregulated phosphorylation of Smad2/3. Additional analysis revealed that Fibroblast growth factor 9 (FGF9) is a direct target of lncRNA FAF, as the overexpression of lncRNA FAF could increase the expression of FGF9 and knockdown of the FGF9 expression could attenuate the down-regulation of lncRNA FAF on TGFß1-P-Smad2/3 pathway. Furthermore, knockdown of the FGF9 expression also abolished the inhibitory effect of FAF on fibrosis. In summary, we demonstrated that the overexpression of lncRNA FAF could inhibit fibrosis induced by Ang II via the TGFß1-P-Smad2/3 signalling by targeting FGF9 in CFs.

A novel long noncoding RNA FAF inhibits apoptosis via upregulating FGF9 through PI3K/AKT signaling pathway in ischemia-hypoxia cardiomyocytes.

Long noncoding RNAs (lncRNAs) have been increasingly considered to play an important role in the pathological process of various cardiovascular diseases, which often bind to the proximal promoters of the protein-coding gene to regulate the protein expression. However, the functions and mechanisms of lncRNAs in cardiomyocytes have not been fully elucidated. High-throughput RNA sequencing was performed to identify the differently expressed lncRNAs and messenger RNAs (mRNAs) between acute myocardial infarction (AMI) rats and healthy controls. One novel lncRNA FGF9-associated factor (termed FAF) and mRNAs in AMI rats were verified by bioinformatics, real-time polymerase chain reaction or western blot. Moreover, RNA fluorescence in situ hybridization was performed to determine the location of lncRNA. Subsequently, a series of in vitro assays were used to observe the functions of lncRNA FAF in cardiomyocytes. The expression of lncRNA FAF and FGF9 were remarkably decreased in ischemia-hypoxia cardiomyocytes and heart tissues of AMI rats. Overexpression of FAF could significantly inhibit cardiomyocytes apoptosis induced by ischemia and hypoxia. Conversely, knockdown of lncRNA FAF could promote apoptosis in ischemia-hypoxia cardiomyocytes. Moreover, overexpression of lncRNA FAF could also increase the expression of FGF9. Knockdown of the FGF9 expression could promote apoptosis in cardiomyocytes with the insult of ischemia and hypoxia, which was consistent with the effect of lncRNA FAF overexpression on cardiomyocyte apoptosis. Mechanistically, FGF9 inhibited cardiomyocytes apoptosis through activating signaling tyrosine kinase FGFR2 via phosphoinositide 3-kinase/protein kinase B signaling pathway. Thus, lncRNA FAF plays a protective role in ischemia-hypoxia cardiomyocytes and may serve as a treatment target for AMI.

A pilot clinical study of adjunctive therapy with selective intracoronary hypothermia in patients with ST-segment elevation myocardial infarction.

OBJECTIVES: We aimed to assess the effect of selective intracoronary hypothermia on outcomes in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). BACKGROUND: Intracoronary hypothermia, the feasibility and safety of which has been validated in humans, induced by selective trans-coronary infusion of saline at different temperatures can reduce infarct size (IS) prior to reperfusion in animal models of STEMI. METHODS: Sixty STEMI patients presenting with thrombolysis in myocardial infarction (TIMI) flow grade 0/1 were randomized after coronary artery angiography. Intracoronary hypothermia was induced by selective trans-coronary infusion of saline at 4°C to the endangered myocardium in the 30 patients. The primary endpoint, absolute IS expressed as IS/myocardium at risk (MaR), was assessed by cardiac magnetic resonance imaging at day 7 post-PPCI in 50 patients. Clinical follow-up was undertaken at day 30 after procedure. RESULTS: Intracoronary hypothermia was successfully performed in hypothermia group, without increase in arrhythmia or hemodynamic instability. The mean temperature reduction of 5.8 ± 1.1°C in distal coronary artery was achieved before reperfusion. Mean IS/MaR was predominantly reduced in the hypothermia group (44.85 ± 5.89% vs. 50.69 ± 10.75%, P = 0.022), especially in the anterior STEMI subgroup (46.12 ± 7.54% vs. 55.27 ± 11.175%, P = 0.023). The clinical events appeared no statistical difference between the two groups at the 30-day follow-up. CONCLUSION: The statistical difference in IS/MaR by intracoronary hypothermia as adjunctive therapy to PPCI is an important observation and warrants a larger pivotal trial fully powered for efficacy.

Mutagen-induced phytotoxicity in maize seed germination is dependent on ROS scavenging capacity.

Ethidium bromide (EB) and acridine orange (AO) bind to nucleic acids and are thus considered as potential mutagens. In this study, the effects of EB and AO on the germination behaviours of white, yellow, red, and purple maize seeds were investigated. The results indicate that low concentrations of EB (50 µg mL-1) and AO (500 µg mL-1) promote germination, particularly for the white and yellow seeds. However, high concentrations of EB (0.5 mg mL-1) and AO (5 mg mL-1) significantly inhibit germination, with the level of inhibition decreasing in the following order: white > yellow > red > purple. In addition, EB and AO induce H2O2 production in a concentration-dependent manner. The effects of these mutagens on seed germination were partly reversed by dimethyl thiourea, a scavenger of reactive oxygen species (ROS), and diphenylene iodonium (DPI), an inhibitor of NADPH oxidase, while the effects were enhanced by treatment with H2O2 and 3-amino-1,2,4-triazole, a specific inhibitor of catalase. In addition, AO and EB profoundly increased NADPH oxidase activities in germinating seeds. The treatment of seeds with EB and AO did not affect the growth or drought tolerance of the resultant seedlings. The findings suggest that the mechanism of mutagen toxicity is related to the induction of ROS production.

Green tea polyphenol epigallocatechin-3-gallate increases atherosclerotic plaque stability in apolipoprotein E-deficient mice fed a high-fat diet.

BACKGROUND: Epigallocatechin-3-gallate (EGCG), which is the principal component of green tea, has been shown to prevent atherosclerosis. However, the effect of EGCG on atherosclerotic plaque stability remains unknown. AIM: This study aimed to assess whether EGCG can enhance atherosclerotic plaque stability and to investigate the underlying mechanisms. METHODS: Apolipoprotein E-deficient mice fed a high-fat diet were injected intraperitoneally with EGCG (10 mg/kg) for 16 weeks. Cross sections of the brachiocephalic arteries were stained with haematoxylin and eosin for morphometric analyses or Masson's trichrome for collagen content analyses. Immunohistochemistry was performed to evaluate the percentage of macrophages and smooth muscle cells (SMCs). Protein expression and matrix metalloproteinase (MMP) activity were assayed by Western blot and gelatin zymography, respectively. Serum inflammatory cytokine levels were quantified by enzyme-linked immunosorbent assays. RESULTS: After 16 weeks of feeding the high-fat diet, there were clear atherosclerotic lesions in the proximal brachiocephalic artery segments according to HE staining. EGCG treatment significantly increased the thickness of the fibrous cap. In the atherosclerotic plaques of the EGCG group, the relative macrophage content was decreased, whereas the relative SMC and collagen contents were increased. The expression levels of MMP-2, MMP-9, and extracellular matrix metalloproteinase inducer (EMMPRIN) were significantly decreased by EGCG treatment. In addition, EGCG treatment decreased the circulat-ing tumour necrosis factor-α, interleukin-6, monocyte chemoattractant protein-1, and interferon-γ levels in apolipoprotein E-deficient mice. CONCLUSIONS: EGCG promotes atherosclerotic lesion stability in apolipoprotein E-deficient mice. Potentially, these effects are mediated through the inhibition of inflammatory cytokine, MMPs and EMMPRIN expression.

Long Noncoding RNA Kcna2 Antisense RNA Contributes to Ventricular Arrhythmias via Silencing Kcna2 in Rats With Congestive Heart Failure.

BACKGROUND: Congestive heart failure (CHF) is a common cardiovascular disease that is often accompanied by ventricular arrhythmias. The decrease of the slow component of the delayed rectifier potassium current (IKs) in CHF leads to action potential (AP) prolongation, and the IKs is an important contributor to the development of ventricular arrhythmias. However, the molecular mechanisms underlying ventricular arrhythmias are still unknown. METHODS AND RESULTS: Kcna2 and Kcna2 antisense RNA (Kcna2 AS) transcript expression was measured in rat cardiac tissues using quantitative real-time reverse transcription-polymerase chain reaction and Western blotting. There was a 43% reduction in Kcna2 mRNA in the left ventricular myocardium of rats with CHF. Kcna2 knockdown in the heart decreased the IKs and prolonged APs in cardiomyocytes, consistent with the changes observed in heart failure. Conversely, Kcna2 overexpression in the heart significantly attenuated the CHF-induced decreases in the IKs, AP prolongation, and ventricular arrhythmias. Kcna2 AS was upregulated ≈1.7-fold in rats with CHF and with phenylephrine-induced cardiomyocyte hypertrophy. Kcna2 AS inhibition increased the CHF-induced downregulation of Kcna2. Consequently, Kcna2 AS mitigated the decrease in the IKs and the prolongation of APs in vivo and in vitro and reduced ventricular arrhythmias, as detected using electrocardiography. CONCLUSIONS: Ventricular Kcna2 AS expression increases in rats with CHF and contributes to reduced IKs, prolonged APs, and the occurrence of ventricular arrhythmias by silencing Kcna2. Thus, Kcna2 AS may be a new target for the prevention and treatment of ventricular arrhythmias in patients with CHF.

Study on association of working hours and occupational physical activity with the occurrence of coronary heart disease in a Chinese population.

OBJECTIVE: To explore the association of working hours and occupational physical activity (OPA) with the occurrence of coronary heart disease (CHD) in a Chinese population. METHODS: A total of 595 participants (354 and 241 patients with and without CHD, respectively) aged between 24 and 65 were enrolled in our study, which was conducted at the First Affiliated Hospital of Nanjing Medical University between December 2015 and October 2016. Participant characteristics were collected from face-to-face questionnaires, and logistic regression analysis was conducted to examine the association of working hours and OPA with the occurrence of CHD. RESULTS: Compared with non-employed people, long working hours (especially ≥55 hours/week) contributed to the occurrence of CHD (adjusted odds ratio[OR] = 2.213, 95% confidence interval [CI]: 1.125, 4.355, P = 0.021) after multivariate adjustment in the Chinese population. With the extension of worktime, the CHD risk increased (P for the dose-response trend = 0.022). Meanwhile, even after adjusting for engagement in physical activity during leisure time, sedentary behavior at work had an adverse effect on CHD risk (adjusted OR = 2.794, 95%CI: 1.526, 5.115, P = 0.001), and a linear relationship was also found between OPA and CHD (P for the trend = 0.005). CONCLUSIONS: Long working hours and sedentary behavior at work are associated with a high risk of CHD. In addition, prolonged working hours in sedentary occupations increases the risk of CHD, independent of engagement in leisure time physical activity.

Epigallocatechin-3-Gallate Inhibits Matrix Metalloproteinase-9 and Monocyte Chemotactic Protein-1 Expression Through the 67-κDa Laminin Receptor and the TLR4/MAPK/NF-κB Signalling Pathway in Lipopolysaccharide-Induced Macrophages.

BACKGROUND/AIMS: Epigallocatechin-3-gallate (EGCG), a major catechin found in green tea, has been shown to prevent cardiovascular diseases. Previously, Matrix metalloproteinase-9 (MMP-9), monocyte chemotactic protein-1 (MCP-1) and toll-like receptor 4 (TLR4) were confirmed to play an important role in atherosclerosis and plaque instability. Both TLR4 and its negative regulator, Toll-interacting protein (Tollip), could be mediated by EGCG. The present study aimed to examine the effect of physiological concentration of EGCG (1 µM) on the expression of MMP-9 and MCP-1 in lipopolysaccharide (LPS)-induced macrophages and the potential mechanisms underlying its actions. METHODS: The RAW264.7 cell line was used. Western blot was used to determine MCP-1, TLR4, Tollip, Mitogen-activated protein kinase (MAPK) and Nuclear factor-κB (NF-κB) protein expression. MMP-9 activity was assayed by gelatine zymography. The mRNA expression of MMP-9 and MCP-1 was measured by realtime polymerase chain reaction (RT-PCR). RESULTS: EGCG (1 µM) significantly suppressed the expression of MMP-9 and MCP-1 and inhibited MAPK and NF-κB in LPS-induced macrophages but was blocked by Tollip silencing. The expression of LPS-induced MMP-9 and MCP-1 and the phosphorylation of the ERK1/2, P38 and NF-κB pathway proteins decreased after TLR4 siRNA treatment. Furthermore, EGCG mediated TLR4 and Tollip expression through binding to 67-kDa laminin receptor (67LR). CONCLUSION: The results of our study suggested that EGCG (1 µM) suppresses the TLR4/MAPK/NF-κB signalling pathway, decreases the expression of the plaque instability-mediating cytokines MMP-9 and MCP-1, and might prove to be effective in stabilizing atherosclerotic plaque.

Association between pet ownership and coronary artery disease in a Chinese population.

A number of studies have suggested the benefits of pet ownership to human health, including cardiovascular disease (CVD). However, there are few findings regarding pet ownership and coronary artery disease (CAD). The objective of this study is to investigate the association between pet ownership and CAD in a Chinese population. From October 2015 to May 2016, a survey consisting of 561 consecutive patients was done in Nanjing, China. Based on the results of coronary arteriography for the first time, participants were divided into 2 groups (non-CAD and CAD groups). Pet ownership information was collected by using a questionnaire. After multivariate adjustments, pet ownership was associated with a decreased CAD risk (odds ratios [OR]: 0.504, 95% confidence intervals [CIs]: 0.310-0.819). There was a reduced CAD risk among dog owners (OR: 0.420, 95% CI: 0.242-0.728) when compared with the cat group (OR: 0.738, 95% CI: 0.240-2.266) and the cat and dog group (OR: 1.052, 95% CI: 0.330-3.355). With the increase of pet ownership duration, there was a decreased tendency of CAD risk, including years of keeping pets (P for trend = 0.008) and time of playing with pets per day (P for trend = 0.001). In addition, similar dose-response relationship was observed for starting age of keeping pets (P for trend = 0.002). Pet ownership, especially dog ownership, can be a protective factor for CAD in Chinese patients.

Harpin-induced expression and transgenic overexpression of the phloem protein gene AtPP2-A1 in Arabidopsis repress phloem feeding of the green peach aphid Myzus persicae.

BACKGROUND: Treatment of plants with HrpNEa, a protein of harpin group produced by Gram-negative plant pathogenic bacteria, induces plant resistance to insect herbivores, including the green peach aphid Myzus persicae, a generalist phloem-feeding insect. Under attacks by phloem-feeding insects, plants defend themselves using the phloem-based defense mechanism, which is supposed to involve the phloem protein 2 (PP2), one of the most abundant proteins in the phloem sap. The purpose of this study was to obtain genetic evidence for the function of the Arabidopsis thaliana (Arabidopsis) PP2-encoding gene AtPP2-A1 in resistance to M. persicae when the plant was treated with HrpNEa and after the plant was transformed with AtPP2-A1. RESULTS: The electrical penetration graph technique was used to visualize the phloem-feeding activities of apterous agamic M. persicae females on leaves of Arabidopsis plants treated with HrpNEa and an inactive protein control, respectively. A repression of phloem feeding was induced by HrpNEa in wild-type (WT) Arabidopsis but not in atpp2-a1/E/142, the plant mutant that had a defect in the AtPP2-A1 gene, the most HrpNEa-responsive of 30 AtPP2 genes. In WT rather than atpp2-a1/E/142, the deterrent effect of HrpNEa treatment on the phloem-feeding activity accompanied an enhancement of AtPP2-A1 expression. In PP2OETAt (AtPP2-A1-overexpression transgenic Arabidopsis thaliana) plants, abundant amounts of the AtPP2-A1 gene transcript were detected in different organs, including leaves, stems, calyces, and petals. All these organs had a deterrent effect on the phloem-feeding activity compared with the same organs of the transgenic control plant. When a large-scale aphid population was monitored for 24 hours, there was a significant decrease in the number of aphids that colonized leaves of HrpNEa-treated WT and PP2OETAt plants, respectively, compared with control plants. CONCLUSIONS: The repression in phloem-feeding activities of M. persicae as a result of AtPP2-A1 overexpression, and as a deterrent effect of HrpNEa treatment in WT Arabidopsis rather than the atpp2-a1/E/142 mutant suggest that AtPP2-A1 plays a role in plant resistance to the insect, particularly at the phloem-feeding stage. The accompanied change of aphid population in leaf colonies suggests that the function of AtPP2-A1 is related to colonization of the plant.

Transcription factor AtMYB44 regulates induced expression of the ETHYLENE INSENSITIVE2 gene in Arabidopsis responding to a harpin protein.

AtMYB44 is a transcription factor that functions in association with the ethylene-signaling pathway in Arabidopsis thaliana. The pathway depends on ETHYLENE INSENSITIVE2 (EIN2), an essential component of ethylene signaling, to regulate defense responses in the plant following treatment with HrpN(Ea), a harpin protein from a bacterial plant pathogen. Here, we show that AtMYB44 regulates induced expression of the EIN2 gene in HrpN(Ea)-treated Arabidopsis plants. A HrpN(Ea) and ethylene-responsive fragment of the AtMYB44 promoter is sufficient to support coordinate expression of AtMYB44 and EIN2 in specific transgenic Arabidopsis. In the plant, the AtMYB44 protein localizes to nuclei and binds the EIN2 promoter; the HrpN(Ea) treatment promotes AtMYB44 production, binding activity, and transcription of AtMYB44 and EIN2. AtMYB44 overexpression results in increased production of the AtMYB44 protein and the occurrence of AtMYB44-EIN2 interaction under all genetic backgrounds of wild-type Arabidopsis and the etr1-1, ein2-1, ein3-1, and ein5-1 mutants, which have defects in the ethylene receptor ETR1 and the signal regulators EIN2, EIN3, and EIN5. However, AtMYB44 overexpression leads to enhanced EIN2 expression only under backgrounds of wild type, ein3-1, and ein5-1 but not etr1-1 and ein2-1, suggesting that ethylene perception is necessary to the regulation of EIN2 transcription by AtMYB44.

Thirty-seven transcription factor genes differentially respond to a harpin protein and affect resistance to the green peach aphid in Arabidopsis.

The harpin protein HrpN Ea induces Arabidopsis resistance to the green peach aphid by activating the ethylene signalling pathway and by recruiting EIN2, an essential regulator of ethylene signalling, for a defence response in the plant. We investigated 37 ethylene-inducible Arabidopsis transcription factor genes for their effects on the activation of ethylene signalling and insect defence. Twenty-eight of the 37 genes responded to both ethylene and HrpN Ea, and showed either increased or inhibited transcription, while 18 genes showed increased transcription not only by ethylene but also by HrpN Ea. In response to HrpN Ea, transcription levels of 22 genes increased, with AtMYB44 being the most inducible, six genes had decreased transcript levels, and nine remained unchanged. When Arabidopsis mutants previously generated by mutagenicity at the 37 genes were surveyed, 24 mutants were similar to the wild type plant while four mutants were more resistant and nine mutants were more susceptible than wild type to aphid infestation. Aphid-susceptible mutants showed a greater susceptibility for atmyb15, atmyb38 and atmyb44, which were generated previously by T-DNA insertion into the exon region of AtMYB15 and the promoter regions of AtMYB38 and AtMYB44. The atmyb44 mutant was the most susceptible to aphid infestation and most compromised in induced resistance. Resistance accompanied the expression of PDF1.2, an ethylene signalling marker gene that requires EIN2 for transcription in wild type but not in atmyb15, atmyb38, and atmyb44, suggesting a disruption of ethylene signalling in the mutants. However, only atmyb44 incurred an abrogation in induced EIN2 expression, suggesting a close relationship between AtMYB44 and EIN2.