Induction of systemic resistance in rice by leaf extracts of Datura metel against sheath blight disease

The leaf extracts of Datura metel [both aqueous leaf extract (ALE) and ethanolic leaf extract (ELE)] were observed here to find if they can induce systemic resistance in the rice commonly found in Eastern India. The results showed that after the treatment, the enzyme activities of all the defence-related enzymes increased to a certain level even without pathogenic infection in comparison with non-treated seedlings and then, maintain at constant level throughout the study period. When treated seedlings were infected with Rhizoctonia solani, the enzyme activities were increased more than in uninfected seedlings. The elevated enzyme activities gave the indication of an induced systemic resistance in rice. The ELE of D. metel showed better induction effect than ALE.     

Ibuprofen reverts antifungal resistance on Candida albicans showing overexpression of CDR genes

Several mechanisms may be associated with Candida albicans resistance to azoles. Ibuprofen was described as being able to revert resistance related to efflux activity in Candida . The aim of this study was to uncover the molecular base of antifungal resistance in C. albicans clinical strains that could be reverted by ibuprofen. Sixty-two clinical isolates and five control strains of C. albicans were studied: the azole susceptibility phenotype was determined according to the Clinical Laboratory for Standards Institute, M27-A2 protocol and minimal inhibitory concentration values were recalculated with ibuprofen (100 μg mL⁻¹); synergistic studies between fluconazole and FK506, a Cdr1p inhibitor, were performed using an agar disk diffusion assay and were compared with ibuprofen results. Gene expression was quantified by real-time PCR, with and without ibuprofen, regarding CDR1 , CDR2 , MDR1 , encoding for efflux pumps, and ERG11 , encoding for azole target protein. A correlation between susceptibility phenotype and resistance gene expression profiles was determined. Ibuprofen and FK506 showed a clear synergistic effect when combined with fluconazole. Resistant isolates reverting to susceptible after incubation with ibuprofen showed CDR1 and CDR2 overexpression especially of the latter. Conversely, strains that did not revert displayed a remarkable increase in ERG11 expression along with CDR genes. Ibuprofen did not alter resistance gene expression significantly ( P >0.05), probably acting as a Cdrp blocker.     

The induction of systemic resistance in barley to powdery mildew infection using salicylates and various phenolic acids

Treatment of the first leaves of barley seedlings with either 5, 10, 15 or 20 mM salicylic acid, sodium salicylate or acetylsalicylic acid resulted in significant reductions in powdery mildew infection on the upper, second leaves. In general, the greatest reduction in mildew infection on the second leaves was obtained by spraying the first leaves with a 15 mM concentration of the compounds. Although the largest reduction in mildew infection of the upper leaves was obtained when the compounds were applied to the first leaves 1–2 days before inoculation, very substantial reductions in infection were still obtained if the first leaves were treated 12 days before inoculation. The three compounds had little direct effect on mildew infection. When ¹⁴C-salicylic acid was fed to first leaves of barley seedlings, uptake was rapid and increased with time. Within 6 h, 0.2% of the salicylic acid appeared in the second leaf and by 24 h after feeding, this had increased to 1.4% (1.1 μmol salicylic acid g^-1 fresh wt). The application of various phenolic acids to first leaves also led to reductions in mildew infection on the second leaves. In particular, treatment of the first leaves with 1 mM vanillic acid, isovanillic acid or syringic acid, reduced mildew infection of the second leaves by 81–87%.     

Cu2+ reduces hemolytic activity of the antimicrobial peptide HMPI and enhances its trypsin resistance

Nowadays,drug-resistant microbes are becoming a serious clinical problem threatening people's health and life.Antimicrobial peptides (AMPs) are believed to be p...     

Comparative evaluation of Pseudomonas fluorescens and their lipopolysaccharides as implicated in induction of resistance against pearl millet downy mildew

Two plant growth promoting Pseudomonas fluorescens isolates namely UOM SAR 14 and UOM SAR 80 most effectively induced resistance against downy mildew disease of pearl millet both under greenhouse and field conditions. Relative assessment of live cultures of P. fluorescens UOM SAR 14 and UOM SAR 80 and their lipopolysaccharides (LPS) extracted from their cell walls were evaluated for their ability to induce resistance against pearl millet downy mildew. Treatment with P. fluorescens and their LPS enhanced the seed germination and seedling vigour considerably. Although both live cultures and their LPS treatment induced resistance in pearl millet against downy mildew disease both under greenhouse and field conditions as evidenced by the significant reduction of the disease, live cultures were more effective than the LPS in level of resistance induced. Live cultures of UOM SAR 14 and UOM SAR 80 induced 66% and 57% protection while their respective LPS extracts offered 59 and 53% protection against downy mildew disease under greenhouse conditions. Similarly, under field conditions with very heavy inoculum pressure live cultures offered 75% and 70%, and their LPS offered 71% and 67% protection, respectively. In either case, the time gap required for the building up of resistance was found to be 3 days and nature of the resistance induced was systemic and durable with both live cultures and their lipopolysaccharides. It was also noticed that the live bacteria significantly varied in the degree of protection offered and so also their respective LPS.     

Hyaluronic acid of Streptococcus sp. as a potent elicitor for induction of systemic resistance against plant diseases

The potential of hyaluronic acid (HA) in inducing systemic resistance to cucumber, tomato and pepper was tested in planta. In the study, HA was found to be a potent agent for suppressing disease caused by Cucumber Mosaic Virus (CMV) (in pepper), Pseudomonas syringae pv. tomato (tomato speck disease), Xanthomonas axonopodis pv. vesicatoria (tomato spot disease), Pseudomonas syringae pv. lachrymans (cucumber angular leaf spot), and Colletotrichum orbiculare (cucumber anthracnose). Disease control was obtained with spraying, injection and drenching of plants with HA. HA did not exhibit direct antimicrobial action against the pathogens tested. Studies carried out in transgenic tobacco indicated that defense genes PR 1a and PDF 1.2 were activated upon treatment with HA, demonstrating salicylic acid (SA) and jasmonic acid (JA) pathways getting activated during defense. Further work is warranted to evaluate the use of HA-mediated disease suppression in crop plants.     

覆盆子提取物联合唑类药物抗真菌活性研究

目的 探讨中药覆盆子提取物联合唑类药物的体外抗真菌作用.方法 采用CLSI公布的M27-A方案微量液基稀释法和棋盘式微量稀释法,测定覆盆子提取物单用及联合唑类药物对不同念珠菌的MIC值和FICI指数.结果 覆盆子不同溶液提取物与氟康唑均表现出协同关系,以覆盆子醇提物为例,单用对念珠菌的MIC80测定值范围主要集中在0.16～1.25 mg/mL,与氟康唑合用后表现出协同关系(FICI≤0.5),且MIC80测定值范围降至0.01 ～0.04 mg/mL;合用后的氟康唑抗真菌活性也明显增强.另外,覆盆子醇提物与不同唑类药物合用后均有协同关系,其MIC80测定值由单用时大于10 mg/mL降至0.04 mg/mL.结论 覆盆子醇提物和唑类药物单用时对耐药念珠菌的抑菌作用较弱,但二者合用后表现出明显的协同关系,对耐药念珠菌的抑菌作用明显增强.     

Elicitation of systemic resistance and growth promotion of Arabidopsis thaliana by PGPRs from Nicotiana glauca: a study of the putative induction pathway

The ability of six putative plant growth promoting rhizobacteria, isolated from the rhizosphere of Nicotiana glauca L., to stimulate growth and induce systemic resistance against Xanthomonas campestris CECT 95 in Arabidopsis thaliana L. Col-0 was evaluated. The six bacterial strains significantly reduced the disease symptoms caused by the pathogen compared to the controls, with the best results obtained with the Bacillus strain N11.37 and the Stenotrophomonas strain N6.8. These two strains were tested on A. thaliana NahG plants and jar1-1 and etr1-1 mutants, to elucidate whether the salicylic acid (SA)-dependent or SA-independent pathway was involved in the induction of systemic resistance. The results indicate that N6.8 induces the SA-dependent pathway. For N11.37 it is as yet not clear as in the etr1-1 mutants and NahG plants ISR is not expressed, while in jar1-1 it is. In addition, levels of SA were measured in Col-0 plants treated with N6.8 and N11.37 to confirm whether or not the two strains produced an increased level of SA. N6.8- and N11.37-induced plants showed higher levels of SA than the controls. It is concluded that N6.8 induces a SA-dependent pathway while N11.37 induces a pathway that is both ethylene (ET)- and SA-dependent.     

Association of some plant defense enzyme activities with systemic resistance to early leaf blight and leaf spot induced in tomato plants by azoxystrobin and Pseudomonas fluorescens

Abstract

Azoxystrobin at three different concentrations, namely, 31.25, 62.50 and 125 g a.i. ha^?1 mancozeb (1 kg ha^?1) and Pseudomonas fluorescens (10 kg ha^?1) were evaluated for their efficacy in inducing defense enzymes in tomato against Alternaria solani and Septoria lycopersici. The activity of defense enzymes peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), β-1, 3 glucanase, chitinase, catalase and defense-inducing chemicals (total phenols) was found to be increased in azoxystrobin and P. fluorescens-treated tomato plants. The activity of these defense enzymes and chemicals was higher in azoxystrobin (125 g a.i. ha^?1) and P. fluorescens-treated tomato plants challenge inoculated with the pathogens compared to other treatments. Increased expression of specific isoforms of PO and PPO was also observed due to ISR induction.     

短期联合应用灰黄霉素、克霉唑和地塞米松对红色毛癣菌的影响

目的研究灰黄霉素、克霉唑及灰黄霉素、克霉唑与地塞米松组合成的联合药物对红色毛癣菌在体内、外活性影响。方法在体外分别应用灰黄霉素、地塞米松、克霉唑、灰黄霉素：克霉唑：地塞米松=5：5：1联合药物的不同药物浓度作用于红色毛癣菌,确立药物最小抑菌浓度（MIC）和联合药物的分数抑菌浓度（FIC）;制作由红色毛癣菌引起皮肤癣的豚鼠动物模型,根据豚鼠用药部位分成四组,对豚鼠皮疹进行疗效的评估。结果体外实验联合药物的MIC小于单药的MIC,且联合药物起协同和次协同作用;体内实验中联合用药组对动物受损局部皮肤给药后,对红色毛癣菌所致皮损积分为（1．89±0．68）,与对照组（3．33±0．69）比较,可明显减轻局部皮肤损伤病变程度,该药优于克霉唑组（2．33±0．69）、灰黄霉素组（2．11±0．58）。结论短期内灰黄霉素、克霉唑与地塞米松组合成的联合药物有较强的抗红色毛癣菌和抗炎作用,其抗菌活性强于单独药物的灰黄霉素和克霉唑。     

Systemic induction of phloem secondary metabolism and its relationship to resistance to a canker pathogen in Austrian pine

The mechanisms and conditions affecting expression of systemic induced resistance (SIR) in pine are not clearly understood. Two hypotheses were tested here: that SIR against a pathogen induced by either a pathogen or an insect involves coordinated shifts in phloem secondary metabolism; and that fertility affects the production of these compounds. To test these hypotheses, a tripartite system was used comprising Austrian pine (Pinus nigra) grown under three different fertility regimes, the fungal pathogen Diplodia pinea, and the defoliator Neodiprion sertifer. Fungal induction led to systemic accumulation of lignin, phenolic glycosides and stilbenes, whereas insect defoliation led to an increase in germacrene D concentration in branch phloem. Fertility affected the concentrations of only the phenolic glycosides. Multivariate analyses showed coregulation of compounds within at least three consistent groupings: phenolic glycosides, stilbenes and monoterpenes. As groups and as individual compounds, accumulation of phenolic glycosides and stilbenes was negatively correlated with disease susceptibility. The experimental manipulation of the phenolics and terpenoids metabolic networks achieved in this study by biotic induction and changes in nutrient availability suggests that lignin, phenolic glycosides and stilbenes are important biochemical factors in the expression of SIR against the pathogen in this system.     

转天麻抗真菌蛋白GAFP基因烟草的获得及离体抑菌活性检测

通过根癌农杆菌(Agrobacteriumtumefaciens)介导,采用叶盘法将天麻(GastrodiaelataBl.)抗真菌蛋白基因GAFP转入烟草(NicotianatabacumL.),PCR和Southern blotting分析证明已将GAFP基因整合进烟草植株。体外抑菌实验表明GAFP转基因的烟草植株对真菌瑞氏木霉(Trichodermareesei)表现出一定的抑菌活性。     

Synthesis,spectral characterization,and in vitro antibacterial and antifungal activities of novel 1,3-thiazine-2-amines comprising morpholine nucleus

A collection of 4-(4-morpholinophenyl)-6-aryl-6H-1,3-thiazin-2-amines (20–28) were synthesized and their in vitro antimicrobial activity was investigated. Compound 21 against P. aeruginosa, 23 against B. subtilis, 24 against V. cholerae and P. aeruginosa, 26 against S. aureus and B. subtilis, 27 against B. subtilis and E. coli, and 28 against all tested bacterial strains exerted excellent antibacterial activity. Compound 20 against A. flavus and Rhizopus, 21, 26 against Rhizopus, 22, 27 against Mucor, 23 against A. flavus, 24 against both A. flavus and Mucor, 25 against all tested strains, and 28 against Rhizopus and M. gypseum exerted excellent antifungal activity.     

Protein composition of tobacco leaves with antiviral resistance induced by activators of defense responses and TMV infection

In tobacco (Nicotiana tabacum L.) plants of hypersensitive cv. Samsun NN, a capability of necrosis lesion formation and protein patterns were studied after induction of antiviral resistance by defense responses activators (DRA) (arachidonic acid, ubiquinone 50, and vitamin E) and by infection with tobacco mosaic virus (TMV). DRA and TMV improved both local and systemic leaf resistance to TMV. Native protein electrophoresis demonstrated differences in the composition of leaf proteins extracted under acidic and alkaline conditions. SDS-PAGE revealed proteins accumulated during the development of systemic antiviral resistance after lower leaf treatments with DRA and of local resistance induced by pretreatment with TMV. It was shown that various DRA affected protein patterns similarly, whereas TMV infection resulted in other changes. It is supposed that different pathways function in tobacco plants during induction of systemic resistance by DRA and TMV infection.     

Characterization of anticancer,DNase and antifungal activity of pumpkin 2S albumin

The plant 2S albumins exhibit a spectrum of biotechnologically exploitable functions. Among them, pumpkin 2S albumin has been shown to possess RNase and cell-free translational inhibitory activities. The present study investigated the anticancer, DNase and antifungal activities of pumpkin 2S albumin. The protein exhibited a strong anticancer activity toward breast cancer (MCF-7), ovarian teratocarcinoma (PA-1), prostate cancer (PC-3 and DU-145) and hepatocellular carcinoma (HepG2) cell lines. Acridine orange staining and DNA fragmentation studies indicated that cytotoxic effect of pumpkin 2S albumin is mediated through induction of apoptosis. Pumpkin 2S albumin showed DNase activity against both supercoiled and linear DNA and exerted antifungal activity against Fusarium oxysporum. Secondary structure analysis by CD showed that protein is highly stable up to 90 °C and retains its alpha helical structure. These results demonstrated that pumpkin 2S albumin is a multifunctional protein with host of potential biotechnology applications.