Brassinosteroids (BRs) play essential roles in modulating plant growth, development and stress responses. Here, involvement of BRs in plant systemic resistance to virus was studied. Treatment of ...local leaves in Nicotiana benthamiana with BRs induced virus resistance in upper untreated leaves, accompanied by accumulations of H₂O₂ and NO. Scavenging of H₂O₂ or NO in upper leaves blocked BR‐induced systemic virus resistance. BR‐induced systemic H₂O₂ accumulation was blocked by local pharmacological inhibition of NADPH oxidase or silencing of respiratory burst oxidase homolog gene NbRBOHB, but not by systemic NADPH oxidase inhibition or NbRBOHA silencing. Silencing of the nitrite‐dependent nitrate reductase gene NbNR or systemic pharmacological inhibition of NR compromised BR‐triggered systemic NO accumulation, while local inhibition of NR, silencing of NbNOA1 and inhibition of NOS had little effect. Moreover, we provide evidence that BR‐activated H₂O₂ is required for NO synthesis. Pharmacological scavenging or genetic inhibiting of H₂O₂ generation blocked BR‐induced systemic NO production, but BR‐induced H₂O₂ production was not sensitive to NO scavengers or silencing of NbNR. Systemically applied sodium nitroprusside rescued BR‐induced systemic virus defense in NbRBOHB‐silenced plants, but H₂O₂ did not reverse the effect of NbNR silencing on BR‐induced systemic virus resistance. Finally, we demonstrate that the receptor kinase BRI1(BR insensitive 1) is an upstream component in BR‐mediated systemic defense signaling, as silencing of NbBRI1 compromised the BR‐induced H₂O₂ and NO production associated with systemic virus resistance. Together, our pharmacological and genetic data suggest the existence of a signaling pathway leading to BR‐mediated systemic virus resistance that involves local Respiratory Burst Oxidase Homolog B (RBOHB)‐dependent H₂O₂ production and subsequent systemic NR‐dependent NO generation.
Systemic resistance is induced by pathogens and confers protection against a broad range of pathogens. Recent studies have indicated that salicylic acid (SA) derivative methyl salicylate (MeSA) ...serves as a long-distance phloem-mobile systemic resistance signal in tobacco, Arabidopsis, and potato. However, other experiments indicate that jasmonic acid (JA) is a critical mobile signal. Here, we present evidence suggesting both MeSA and methyl jasmonate (MeJA) are essential for systemic resistance against Tobacco mosaic virus (TMV), possibly acting as the initiating signals for systemic resistance. Foliar application of JA followed by SA triggered the strongest systemic resistance against TMV. Furthermore, we use a virus-induced gene-silencing-based genetics approach to investigate the function of JA and SA biosynthesis or signaling genes in systemic response against TMV infection. Silencing of SA or JA biosynthetic and signaling genes in Nicotiana benthamiana plants increased susceptibility to TMV. Genetic experiments also proved the irreplaceable roles of MeSA and MeJA in systemic resistance response. Systemic resistance was compromised when SA methyl transferase or JA carboxyl methyltransferase, which are required for MeSA and MeJA formation, respectively, were silenced. Moreover, high-performance liquid chromatography-mass spectrometry analysis indicated that JA and MeJA accumulated in phloem exudates of leaves at early stages and SA and MeSA accumulated at later stages, after TMV infection. Our data also indicated that JA and MeJA could regulate MeSA and SA production. Taken together, our results demonstrate that (Me)JA and (Me)SA are required for systemic resistance response against TMV.
Solid‐state lithium–oxygen (Li–O2) batteries are considered as the next‐generation solution for high‐safety energy storage systems to overcome the persistent problems associated with liquid battery ...systems. However, the absence of stable solid‐state electrolytes (SSEs) and the design complexity of functional solid‐state cathode (SSC) remains a fundamental challenge. Here, a high‐performance solid‐state Li–O2 battery is presented with Li‐ion‐conducted UiO‐67 (UiO‐67‐Li) as SSEs and UiO‐67‐Li@reduced graphene oxide (rGO) aerogel integrated structure as SSC. The UiO‐67‐Li SSEs reveal exceptional conductivity (0.64 mS cm−1 at 25 °C) along with high chemical/electrochemical robustness. Furthermore, the prepared UiO‐67‐Li@rGO aerogel exhibits continuous and abundant Li+/e− transfer and O2 diffusion channels. Benefiting from the unique chemical properties of the UiO‐67‐Li SSEs layer, the solid‐state Li–O2 battery achieves suppression of anode dendrite formation, resistance to air‐corrosion, and presence of multiple low‐impedance wetting interfaces including anode/electrolyte and electrolyte/cathode. This ingenious arrangement endows the solid‐state Li–O2 battery with low overpotential (0.8 V), superior rate capability, and stable cycling life (up to 115 cycles). This novel design and exciting result will open up one avenue for the development of MOF‐based SSEs and cathodes for high‐performance solid‐state Li–O2 batteries and other solid‐state energy‐storage devices.
For the first time, a novel integrated solid‐state electrolyte‐cathode structure based on Li‐ion‐conducted UiO‐67 is fabricated, successfully solving the tough problems in solid‐state lithium–oxygen batteries including large resistance, low catalytic activity, and limited triple‐phase boundaries. The elaborated design and achieved electrochemical properties open up a new avenue in constructing high‐performance solid‐state lithium–oxygen batteries.
Plant steroid hormones, brassinosteroids (BRs), play essential roles in plant growth, development and stress responses. However, mechanisms by which BRs interfere with plant resistance to virus ...remain largely unclear. In this study, we used pharmacological and genetic approaches in combination with infection experiments to investigate the role of BRs in plant defense against Tobacco Mosaic Virus (TMV) in Nicotiana benthamiana. Exogenous applied BRs enhanced plant resistance to virus infection, while application of Bikinin (inhibitor of glycogen synthase kinase-3), which activated BR signaling, increased virus susceptibility. Silencing of NbBRI1 and NbBSK1 blocked BR-induced TMV resistance, and silencing of NbBES1/BZR1 blocked Bikinin-reduced TMV resistance. Silencing of NbMEK2, NbSIPK and NbRBOHB all compromised BR-induced virus resistance and defense-associated genes expression. Furthermore, we found MEK2-SIPK cascade activated while BES1/BZR1 inhibited RBOHB-dependent ROS production, defense gene expression and virus resistance induced by BRs. Thus, our results revealed BR signaling had two opposite effects on viral defense response. On the one hand, BRs enhanced virus resistance through MEK2-SIPK cascade and RBOHB-dependent ROS burst. On the other hand, BES1/BZR1 inhibited RBOHB-dependent ROS production and acted as an important mediator of the trade-off between growth and immunity in BR signaling.
Expansins are cell wall-loosening proteins known for their endogenous functions in cell wall extensibility during plant growth. The effects of expansins on plant growth, developmental processes and ...environment stress responses have been well studied. However, the exploration of expansins in plant virus resistance is rarely reported. In the present study, virus-induced gene silencing (VIGS) and Agrobacterium-mediated transient overexpression were conducted to investigate the role of Nicotiana tabacum alpha-expansin 4 (EXPA4) in modulating Tobacco mosaic virus (TMV-GFP) resistance in Nicotiana benthamiana. The results indicated that silencing of EXPA4 reduced the sensitivity of N. benthamiana to TMV-GFP, and EXPA4 overexpression accelerated virus reproduction on tobacco. In addition, our data suggested that the changes of virus accumulation in response to EXPA4 expression levels could further affect the antioxidative metabolism and phytohormone-related pathways in tobacco induced by virus inoculation. EXPA4-silenced plants with TMV-GFP have enhanced antioxidant enzymes activities, which were down-regulated in virus-inoculated 35S:EXPA4 plants. Salicylic acid accumulation and SA-mediated defence genes induced by TMV-GFP were up-regulated in EXPA4-silenced plants, but depressed in 35S:EXPA4 plants. Furthermore, a VIGS approach was used in combination with exogenous phytohormone treatments, suggesting that EXPA4 has different responses to different phytohormones. Taken together, these results suggested that EXPA4 plays a role in tobacco defence against viral pathogens.
Human coronaviruses (HCoV) OC43, 229E, NL63, and HKU1 are common respiratory viruses which cause various respiratory diseases, including pneumonia. There is a paucity of evidence on the epidemiology ...and clinical manifestations of these four HCoV strains worldwide. We collected 11,399 throat swabs from hospitalized children with acute respiratory tract infection from July 2009 to June 2016 in Guangzhou, China. These were tested for four strains of HCoV infection using real-time polymerase chain reaction (PCR). HCoV-positive patients were then tested for 11 other respiratory pathogens. 4.3% (489/11399) of patients were positive for HCoV, of which 3.0% were positive for OC43 (346/11399), 0.6% for 229E (65/11399), 0.5% for NL63 (60/11399), and 0.3% for HKU1 (38/11399). Patients aged 7–12 months had the highest prevalence of HCoV and OC43 when compared with other age groups (
p
< 0.001). The peak seasons of infection varied depending on the HCoV strain. Patients infected with a single strain of HCoV infection were less likely to present fever (≥ 38 °C) (
p
= 0.014) and more likely to present pulmonary rales (
p
= 0.043) than those co-infected with more than one HCoV strain or other respiratory pathogens. There were also significant differences in the prevalence of certain symptoms, including coughing (
p
= 0.032), pneumonia (
p
= 0.026), and abnormal pulmonary rales (
p
= 0.002) according to the strain of HCoV detected. This retrospective study of the prevalence of four HCoV strains and clinical signs among a large population of pediatric patients in a subtropical region of China provides further insight into the epidemiology and clinical features of HCoV.
Acute Respiratory Infections (ARI) are some of the most common human diseases worldwide. However, they have a complex and diverse etiology, and the characteristics of the pathogens involved in ...respiratory infections in developing countries are not well understood. In this work, we analyzed the characteristics of 17 common respiratory pathogens in children (≤14 years old) with ARI in Guangzhou, southern China over a 3-year period using real-time polymerase chain reaction. Pathogens were identified in 2361/4242 (55.7%) patients, and the positivity rate varied seasonally. Ten of the 17 pathogens investigated showed positivity rates of more than 5%. The most frequently detected pathogens were respiratory syncytial virus (768/2361, 32.5%), influenza A virus (428/2361, 18.1%), enterovirus (138/2361, 13.3%), Mycoplasma pneumoniae (267/2361, 11.3%) and adenovirus (213/2361, 9.0%). Co-pathogens were common and found in 503 of 2361 (21.3%) positive samples. When ranked according to frequency of occurrence, the pattern of co-pathogens was similar to that of the primary pathogens, with the exception of human bocavirus, human coronavirus and human metapneumovirus. Significant differences were found in age prevalence in 10 of the 17 pathogens (p≤0.009): four basic patterns were observed, A: detection rates increased with age, B: detection rates declined with age, C: the detection rate showed distinct peaks or D: numbers of patients were too low to detect a trend or showed no significant difference among age groups (p>0.05). These data will be useful for planning vaccine research and control strategies and for studies predicting pathogen prevalence.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Since they function as cell wall-loosening proteins, expansins can affect plant growth, developmental processes and environmental stress responses. Our previous study demonstrated that changes in ...Nicotiana tabacum α-expansin 4 (EXPA4) expression affect the sensitivity of tobacco to Tobacco mosaic virus recombinant TMV encoding green fluorescent protein (TMV-GFP) infection by Agrobacterium-mediated transient expression. In this study, to characterize the function of tobacco EXPA4 further, EXPA4 RNA interfernce (RNAi) mutants and overexpression lines were generated and assayed for their tolerance to abiotic stress and resistance to pathogens. First, the differential phenotypes and histomorphology of transgenic plants with altered EXPA4 expression indicated that EXPA4 is essential for normal tobacco growth and development. By utilizing tobacco EXPA4 mutants with abiotic stress, it was demonstrated that RNAi mutants have increased hypersensitivity to salt and drought stress. In contrast, the overexpression of EXPA4 in tobacco conferred greater tolerance to salt and drought stress, as indicated by less cell damage, higher fresh weight, higher soluble sugar and proline accumulation, and higher expression levels of several stress-responsive genes. In addition, the overexpression lines were more susceptible to the viral pathogen TMV-GFP when compared with the wild type or RNAi mutants. The induction of the antioxidant system, several defense-associated phytohormones and gene expression was down-regulated in overexpression lines but up-regulated in RNAi mutants when compared with the wild type following TMV-GFP infection. In addition, EXPA4 overexpression also accelerated the disease development of Pseudomonas syringae DC3000 on tobacco. Taken together, these results suggested that EXPA4 appears to be important in tobacco growth and responses to abiotic and biotic stress.
Human parainfluenza viruses (HPIVs) are important causes of upper respiratory tract illness (URTI) and lower respiratory tract illness (LRTI). To analyse epidemiologic and clinical characteristics of ...the four types of human parainfluenza viruses (HPIVs), patients with acute respiratory tract illness (ARTI) were studied in Guangzhou, southern China.
Throat swabs (n=4755) were collected and tested from children and adults with ARTI over a 26-month period, and 4447 of 4755 (93.5%) patients' clinical presentations were recorded for further analysis.
Of 4755 patients tested, 178 (3.7%) were positive for HPIV. Ninety-nine (2.1%) samples were positive for HPIV-3, 58 (1.2%) for HPIV-1, 19 (0.4%) for HPIV-2 and 8 (0.2%) for HPIV-4. 160/178 (88.9%) HPIV-positive samples were from paediatric patients younger than 5 years old, but no infant under one month of age was HPIV positive. Seasonal peaks of HPIV-3 and HPIV-1 occurred as autumn turned to winter and summer turned to autumn. HPIV-2 and HPIV-4 were detected less frequently, and their frequency of isolation increased when the frequency of HPIV-3 and HPIV-1 declined. HPIV infection led to a wide spectrum of symptoms, and more "hoarseness" (p=0.015), "abnormal pulmonary breathing sound" (p<0.001), "dyspnoea" (p<0.001), "pneumonia" (p=0.01), and "diarrhoea" (p<0.001) presented in HPIV-positive patients than HPIV-negative patients. 10/10 (100%) HPIV-positive adult patients (≥14 years old) presented with systemic influenza-like symptoms, while 90/164 (54.9%) HPIV-positive paediatric patients (<14 years old) presented with these symptoms (p=0.005). The only significant difference in clinical presentation between HPIV types was "Expectoration" (p<0.001). Co-infections were common, with 33.3%-63.2% of samples positive for the four HPIV types also testing positive for other respiratory pathogens. However, no significant differences were seen in clinical presentation between patients solely infected with HPIV and patients co-infected with HPIV and other respiratory pathogens.
HPIV infection led to a wide spectrum of symptoms, and similar clinical manifestations were found in the patients with four different types of HPIVs. The study suggested pathogenic activity of HPIV in gastrointestinal illness. The clinical presentation of HPIV infection may differ by patient age.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Alpha-momorcharin (α-MMC) is a type-I ribosome inactivating protein with a molecular weight of 29 kDa that is found in
, and has been shown to be effective against a broad range of human viruses as ...well as having anti-tumor activities. However, the role of endogenous α-MMC under viral infection and the mechanism of the anti-viral activities of α-MMC in plants are still unknown. To study the effect of α-MMC on plant viral defense and how α-MMC increases plant resistance to virus, the
-
(CMV) interaction system was investigated. The results showed that the α-MMC level was positively correlated with the resistance of
to CMV. α-MMC treatment could alleviate photosystem damage and enhance the ratio of glutathione/glutathione disulfide in
under CMV infection. The relationship of α-MMC and defense related phytohormones, and their roles in plant defense were further investigated. α-MMC treatment led to a significant increase of jasmonic acid (JA) and vice versa, while there was no obvious relevance between salicylic acid and α-MMC. In addition, reactive oxygen species (ROS) were induced in α-MMC-pretreated plants, in a similar way to the ROS burst in JA-pretreated plants. The production of ROS in both ibuprofen (JA inhibitor) and (α-MMC+ibuprofen)-pretreated plants was reduced markedly, leading to a greater susceptibility of
to CMV. Our results indicate that the anti-viral activities of α-MMC in
may be accomplished through the JA related signaling pathway.
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