Chitinase Research Articles

Biocontrol of grapevine aerial and root pathogens by Paenibacillus sp. strain B2 and paenimyxin in vitro and in planta

Paenibacillus sp. strain B2, isolated from the mycorrhizosphere of Sorghum bicolor, was previously shown to possess antagonistic activity against fungi and bacteria due to the secretion of the peptide paenimyxin. The effects of strain B2 and paenimyxin were assessed against grapevine pathogens as they potentially represent a non-polluting complement or an alternative biocontrol agent to existing disease management strategies. In this study, the effects of Paenibacillus sp. strain B2 and paenimyxin were analyzed in vitro or in planta on the aerial or root pathogens of grapevine Botrytis cinerea, Plasmopara viticola and Xiphinema index. The bacterium significantly reduced B. cinerea development in vitro, and substantially decreased X. index numbers in soil and gall formation in the root system of grapevine plants. In vitro, paenimyxin inhibited the mycelial growth of B. cinerea, the mobility of the zoospores of P. viticola and X. index activity. Supplying paenimyxin at the time of inoculation of leaf tissue with P. viticola decreased infection sites, compared to application prior to fungal inoculation. Using the P. viticola/grapevine pathosystem, we showed that paenimyxin acts as a biopesticide against the oomycete but does not trigger plant defense. Conversely, Paenibacillus sp. strain B2 can induce the expression of the defense genes CHI (chitinase), PR-3 (proteinase inhibitor) and LOX (lipoxygenase). Altogether, the results obtained highlight the interest of Paenibacillus sp. strain B2 and paenimyxin for the biocontrol of different grapevine diseases.

Analysis of chitinase diversity in the Baltic Sea bottom sediments

Analysis of chitinase diversity in the Baltic Sea bottom sediments

Silencing Chitinase Genes Increases Susceptibility of Tetranychus cinnabarinus (Boisduval) to Scopoletin.

The carmine spider mite Tetranychus cinnabarinus is a major pest of crop and vegetable plants worldwide. Previous studies have shown that scopoletin is a promising acaricidal compound against Tetranychus cinnabarinus. However, the acaricidal mechanism of scopoletin remains unclear. In the present study, 12 full-length cDNAs of chitinase (CHIT) genes from Tetranychus cinnabarinus (designated TcCHITs) were cloned and characterized. Although TcCHITs were expressed throughout all life stages, their expression levels were significantly upregulated during the larval and nymphal stages. TcCHITs were downregulated 24 h after treatment with scopoletin and upregulated 24 h after treatment with diflubenzuron (DFB, a chitin synthesis inhibitor). Feeding double-stranded RNA effectively silenced TcCHIT transcription in Tetranychus cinnabarinus, thus increasing its susceptibility to scopoletin but reducing that to DFB. Meanwhile, TcCHIT silencing in larvae and adult resulted in an extremely low molting rate (7.3%) and high mortality rate (53.3%), respectively, compared with those in the control group. CHIT genes are closely related to arthropod survival, molting, and development in Tetranychus cinnabarinus, suggesting that acaricidal mechanisms of scopoletin and DFB may occur by inhibition and activation of CHIT gene expression, respectively. TcCHIT constitutes a possible target of scopoletin and DFB in Tetranychus cinnabarinus.

Hot air treatment activates defense responses and induces resistance against Botrytis cinerea in strawberry fruit

The effect of hot air (HA, 45°C, 3.5 h) treatment on reducing gray mold caused by Botrytis cinerea in strawberry fruit and the possible mechanisms were investigated. The results showed that HA treatment significantly reduced lesion diameter and enhanced activities of chitinase (CHI), β-1,3-glucanase and phenylalanine ammonia-lyase (PAL) in strawberry fruit. Total phenolic contents were also increased by HA treatment. The activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were higher in HA treated strawberry fruit than those in control. Expression of three defense related genes such as CAT, CCR-1 allele and PLA6 was greatly induced in HA treated strawberry fruit with or without inoculation by B. cinerea. In addition, the in vitro experiment showed that HA treatment inhibited spore germination and tube growth of B. cinerea. These results suggested that HA treatment directly activated disease resistance against B. cinerea in strawberry fruit without priming response and directly inhibiting growth of B. cinerea.

Effects of defoliation and site quality on growth and defenses of Pinus pinaster and P. radiata

The susceptibility to pests and pathogens is frequently of only minor consideration by foresters when selecting tree species to plant, but growth reductions from pests and pathogens are commonly large relative to productivity differences among tree species. Because the selection of tree species and sites when establishing plantation forests has potential effects on subsequent damage by pests, there is need for consideration of joint effects of tree species, site quality, and risk of pests. We tested here how site quality influences the response of two pines species that differ in their evolutionary history with a primary pest in the system. Our specific research objectives were to (1) measure the growth response of two pine species (the native Pinus pinaster and the introduced P. radiata) to defoliation by the pine processionary moth, across a gradient of nutrient availability and (2) compare the constitutive and delayed defoliation induced chemical defenses of these two pine species on sites of low and high quality. We analyzed variation in foliar nitrogen, terpenes, tannins, total phenols and four defensive proteins. The impact on tree growth from experimentally applied defoliation by PPM was surprisingly low. Even with complete defoliation, large sample sizes, and baseline measurements that accounted for much of the variation among trees, we observed only modest effects on diameter growth and no effects on height growth; volume growth was initially reduced by only 6–8% initially, with full recovery within 3 years of defoliation. Pinus radiata, the faster growing species, had higher concentrations than P. pinaster of foliar N while P. pinaster had up to 12 times higher concentrations of terpenes, these results match with predictions of the resource availability hypothesis (RAH). Pinus radiata foliage was relatively rich in tannins and total phenolics. The pine species also differed in defensive proteins. Pinuspinaster had higher concentrations of peroxidase (POD), polyphenol oxidase (PPO) and chitinase (CHI), while P. radiata had higher concentrations of trypsin inhibitor (TI). Finally there was no evidence for delayed inducible defenses in either pine species following PPM defoliation; both species seem to use other defensive strategies to counter predictable attacks by the herbivore. In our study region, defoliation by PPM may not be a primary consideration in the selection of pine species for production forests, but this conclusion need not hold in regions where pines grow more slowly or are exposed to multiple years of defoliation by PPM.

MiR-71 and miR-263 Jointly Regulate Target Genes Chitin synthase and Chitinase to Control Locust Molting.

Chitin synthase and chitinase play crucial roles in chitin biosynthesis and degradation during insect molting. Silencing of Dicer-1 results in reduced levels of mature miRNAs and severely blocks molting in the migratory locust. However, the regulatory mechanism of miRNAs in the molting process of locusts has remained elusive. In this study, we found that in chitin metabolism, two crucial enzymes, chitin synthase (CHS) and chitinase (CHT) were regulated by miR-71 and miR-263 during nymph molting. The coding sequence of CHS1 and the 3’-untranslated region of CHT10 contain functional binding sites for miR-71 and miR-263, respectively. miR-71/miR-263 displayed cellular co-localization with their target genes in epidermal cells and directly interacted with CHS1 and CHT10 in the locust integument, respectively. Injections of miR-71 and miR-263 agomirs suppressed the expression of CHS1 and CHT10, which consequently altered chitin production of new and old cuticles and resulted in a molting-defective phenotype in locusts. Unexpectedly, reduced expression of miR-71 and miR-263 increased CHS1 and CHT10 mRNA expression and led to molting defects similar to those induced by miRNA delivery. This study reveals a novel function and balancing modulation pattern of two miRNAs in chitin biosynthesis and degradation, and it provides insight into the underlying molecular mechanisms of the molting process in locusts.

Solidago canadensis L. Essential Oil Vapor Effectively Inhibits Botrytis cinerea Growth and Preserves Postharvest Quality of Strawberry as a Food Model System.

This study investigated the anti-fungal properties of Solidago canadensis L. essential oil (SCLEO) against Botrytis cinerea in vitro, and its ability to control gray mold and maintain quality in strawberry fruits. SCLEO exhibited dose-dependent antifungal activity against B. cinerea and profoundly altered mycelial morphology, cellular ultrastructure, and membrane permeability as evaluated by scanning electron microscopy, transmission electron microscopy, and fluorescence microscopy. SCLEO vapor at 0.1 mL/L maintained higher sensory acceptance and reduced decay of fresh strawberry fruit, and also reduced gray mold in artificially inoculated fruit. SCLEO treatment did not, however, stimulate phenylalanin ammonia-lyase, polyphenol oxidase, or chitinase, enzymes related to disease resistance. This suggests that SCLEO reduces gray mold by direct inhibition of pathogen growth. SCLEO vapor may provide a new and effective strategy for controlling postharvest disease and maintaining quality in strawberries.

Impact of neoadjuvant chemotherapy with gemcitabine and S-1 on postoperative prognosis: A matched case-control study

Two chitinase(CTS)-encoding genes (cts) from Coccidioides immitis (CI), a respiratory fungal pathogen of humans, were cloned and sequenced. Both the genomic and cDNA sequences are presented. The transcription start points and poly(A)-addition sites were confirmed. The cts1 gene contains five introns and a 1281-bp ORF which translates a 427-amino-acid (aa) protein of 47.4 kDa. The cts2 gene contains two introns and a 2580-bp ORF which translates a 860-aa protein of 91.4 kDa. The deduced CTS1 protein showed highest homology to the Aphanocladium album and Trichoderma harzianum CTS (74% and 76%, respectively), while CTS2 showed highest homology to the CTS of Saccharomyces cerevisiae (Sc) and Candida albicans (47% and 51%, respectively). The putative N-terminal sequence of the mature CTS1 protein also showed 89% homology to the reported N-terminal sequence of a 48-kDa complement fixation antigen (CF-Ag) of Ci which has demonstrated chitinase activity. The CFAg is a clinically important antigen used in serodiagnosis of this fungal disease. CTS2 showed several of the conserved features of the Sc CTS, including putative catalytic and Ser/Thr-rich domains, and a C-terminal Cys-rich region. We propose that CTS1 and CTS2 of Ci are members of two distinct classes of fungal chitinases, an observation not previously reported for a single fungus.

THE POTENTIAL ABILITY OF SOME ABIOTIC AGENTS TO CONTROL BARLEY NET BLOTCH DISEASE

The efficacy of some abiotic agents such as chitosan (CHT), xanthan gum (XAN), propolis (PROP) and propiconazol fungicide at its recommended dose (0.25 ml/l) against barley net blotch disease caused by Drechslera teres (D. teres) were evaluated. In vitro trials, CHT proved high inhibition effect on spore germination than on the linear growth of D. teres, while the contrary occurred by PROP. Meanwhile, XAN had not exhibited any direct effect against mycelial growth and spore germinations. In vivo trials, under greenhouse conditions, disease responses at both seedling and adult stages were significantly reduced compared to the control. Both tested concentrations of CHT and propiconazol treatments revealed the highest protection level by reducing the number and rate of lesion increase followed by XAN. Treatments of PROP showed the lower protection level especially at seedling stages. The ability of tested substances to trigger physiological defense reaction in plant tissues was investigated during the assessment of some defense related enzyme activities i.e. peroxidase (POD) chitinase (CHS) and phenylalanine ammonialyase (PAL). The higher activity of POD was obtained by propiconazol, followed by XAN at 0.3% and PROP at 0.6%. Activities of CHS showed the highest stimulation response with PROP at 0.6%, CHT at 0.1 and 0.15%, followed by XAN at 0.3%. However, the lowest response was recorded with the propiconazol. PAL activity was observed to be high in plants treated with propiconazol followed by CHT at 0.1 and 0.15%.

ANTAGONISTIC ACTIVITY OF FUNGI FROM ANTHRACNOSE LESIONS ON PAULLINIA CUPANA AGAINST COLLETOTRICHUM sp.

Anthracnose is a cosmopolitan disease caused by Colletotrichum spp. that affects many crops worldwide. Observations have shown that anthracnose leaf lesions may be colonized by several non-pathogenic microorganisms. The relationship of these microorganisms with the pathogen as well as their potential as biocontrol agents is not well known. Guarana (Paullinia cupana Mart. var. sorbilis) is a typical native Amazon crop with unknown microbial diversity. Guarana productivity has been reduced by a fungal disease caused by Colletotrichum sp. In this study, we isolated 15 fungi from guarana anthracnose leaf lesions that belong to five genera: Fusarium, Phomopsis, Leptosphaeria, Microdochium and Pestalotiopsis. Four isolates from the Fusarium sp. (C6 and C10), Pestalotiopsis sp. (C3), and Microdochium sp. (P7) consistently inhibited anthracnose fungal growth in vitro. Except for the Microdochium sp. (P7), these isolates were also able to inhibit the growth of the pathogen in in vivo assays using detached guarana leaves. Some mechanisms related to the growth inhibition of this pathogen were studied. Fusarium sp. (C6) produced chitinases; Fusarium sp. (C6, C10) and Pestalotiopsis sp. (C3) produced antagonistic volatile organic compounds. These three isolates also inhibited the growth of Fusarium spp., a pathogen of several plant species, suggesting their potential broad range of growth inhibition of other phytopathogens.

Detection and analysis of the characteristic expression of microRNAs of anal fistula patients

To detect and analyze the characteristic miRNAs profile of anal fistula and explore their possible target genes and potential clinical significance. The anal mucosa close to the hemorrhoids were collected from three patients undergoing fistulectomy and hemorrhoidectomy (fistula group) as well as three patients receiving only hemorroidectomy(hemorrhoids group), matching with fistula group in age, gender and body weight. miRNA microarray was used to compare the expression of 1 285 human miRNAs of the anal mucosa between two groups. Cluster analysis was adopted to analyze the accumulation of the differentially expressed miRNAs(P<0.05, fold≥2.0 or ≤0.5) and their target genes were predicted with 10 softwares such as DIANAmT, miRanda, miRDB, miRWalk etc. Comprehensive scoring was performed to identify genes with highest predictive score. Gene ontology (GO) concentration technique was used to analyze the target gene-associated biological process. Immunohistochemistry was used to examine protein expression of genes with the highest score. Among 1285 miRNAs in fistula group, 13 miRNAs were differentially expressed with those in hemorrhoid group, including 2 of up-regulation and 11 of down-regulation. Paired t test showed that in fistula group, miRNA-3609 up-regulation was 5.98 folds(P=0.0231) and miR-181a-2-3p down-regulation was 0.13 folds(P=0.0067) compared to those in hemorrhoid group, which had the greatest differential expression. Cluster analysis suggested that up-regulated miR-3609 and miR-6086 had similar change trend in both groups. Among 11 down-regulated miRNAs, miR-125bp-1-3p and miR-548q had similar expression and other 9 miRNAs had similar expression as well, including miR-1185-1-3p, miR-532-3p, miR-1233-5p, miR-769-5p, miR-149-5p, miR-99b-3p, miR-141-3p, miR-138-5p, and miR-181a-2-3p. Target gene prediction analysis of above 13 genes showed that 7 miRNAs(53.8%) were eligible to predict their potential target genes, yielding totally 104 possible target genes. The rest of 6 miRNAs(46.2%) failed to predict any target gene. The highest score in prediction of target gene was chitinase 1(ChIT1) and its corresponding differential miRNA was miR-769-5p(r=-0.94286, P=0.0167). Gene ontology analysis showed that the most associated biological process related with these 104 target genes was keratinization, immune response and signal transduction. Immunohistochemistry revealed ChiT1 expression of anal mucosa in fistula group was significantly higher compared to hemorrhoid group(P<0.01). There is a characteristic miRNAs profile in anal fistula patients, which may play a role in the occurrence and development of anal fistula.

Construction of prokaryotic expression vector of {\sl Arabidopsis pumila} chitinase and its expression in {\sl Escherichia coil}

Prokaryotic expression vector pET-CH of Arabidopsis pumila chitinase gene cDNA was constructed by means of recombinant gene technology and expressed in Escherichia coil BL21 under induction of IPTG,the expressed products were detected by SDS-PAGE analysis.Result show: Recombinant chitinase was efficiently expressed in E.coli BL21,it molecular weight was about 40 KD.The successful construction of prokaryotic expression vector containing Arabidopsis pumila chitinase gene and effective expression of recombinant chitinase in E. coli BL21 laid the foundation for further study on its biological function.

Biochemical basis of synergism between pathogenic fungus Metarhizium anisopliae and insecticide chlorantraniliprole in Locusta migratoria (Meyen).

We challenged Locusta migratoria (Meyen) grasshoppers with simultaneous doses of both the insecticide chlorantraniliprole and the fungal pathogen, Metarhizium anisopliae. Our results showed synergistic and antagonistic effects on host mortality and enzyme activities. To elucidate the biochemical mechanisms that underlie detoxification and pathogen-immune responses in insects, we monitored the activities of 10 enzymes. After administration of insecticide and fungus, activities of glutathione-S-transferase (GST), general esterases (ESTs) and phenol oxidase (PO) decreased in the insect during the initial time period, whereas those of aryl acylamidase (AA) and chitinase (CHI) increased during the initial period and that of acetylcholinesterase (AChE) increased during a later time period. Activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) decreased at a later time period post treatment. Interestingly, treatment with chlorantraniliprole and M. anisopliae relieved the convulsions that normally accompany M. anisopliae infection. We speculate that locust mortality increased as a result of synergism via a mechanism related to Ca2+ disruption in the host. Our study illuminates the biochemical mechanisms involved in insect immunity to xenobiotics and pathogens as well as the mechanisms by which these factors disrupt host homeostasis and induce death. We expect this knowledge to lead to more effective pest control.

Construction of a recombinant HIV-1 gp140 protein vaccine and evaluation of its immunogenicity

Objective To construct a recombinant HIV-1 gp140 protein vaccine and to evaluate its immunogenicity. Methods Four expression vectors containing different signal peptides including DRVI, IL-2, venom and chitinase were constructed for the expression of gp140 protein clones. Western blot assay was performed to evaluate the expression efficiency of the constructed expression vectors. The cleavage of signal peptides was analyzed by sequencing analysis. The gp140 protein clones with different lengths of C-terminus were constructed and then comparatively analyzed for the screening of optimized recombinant HIV-1 gp140 antigen. Guinea pigs were immunized with different strategies and the potency of vaccination was evaluated by detecting the binding antibodies and neutralizing antibodies after immunization. Results DRVI, the designed signal peptide, had the advantages in determining the efficiency of protein secretion and signal peptide cleavage. Compared with the co-immunization with DNA and recombinant Tiantan vaccinia (rTV) HIV vaccines, immunization of guinea pigs with the recombined gp140 protein vaccine alone could induce higher levels of binding antibodies and neutralizing antibodies. The gp140 protein with long C-terminus was slightly better than the one with short C-terminus in eliciting immune response, but no significant differences were found between them. Conclusion The optimized HIV-1 gp140 protein vaccine with appropriate protein signal peptide and C-terminus was successfully constructed and turned out to be effective in eliciting stronger immune response. Key words: HIV-1 gp140 protein; Antigen design; Immune evaluation

RNA expression profiling in depressed patients suggests retinoid-related orphan receptor alpha as a biomarker for antidepressant response

Gene expression profiling may be a tool to identify markers of antidepressant treatment response and new potential drug targets. In a first step, we selected 12 males, age- and severity-matched pairs of remitters and non-responders, and analyzed expression profiles in peripheral blood at admission and after 2 and 5 weeks of treatment using Illumina expression arrays. We identified 127 transcripts significantly associated with treatment response with a minimal P -value of 9.41×10 −4 (false discovery rate-corrected). Analysis of selected transcripts in an independent replication sample of 142 depressed inpatients confirmed that lower expression of retinoid-related orphan receptor alpha (RORa, P =6.23×10 −4 ), germinal center expressed transcript 2 (GCET2, P =2.08×10 −2 ) and chitinase 3-like protein 2 (CHI3L2, P =4.45×10 −2 ) on admission were associated with beneficial treatment response. In addition, leukocyte-specific protein 1 (LSP1) significantly decreased after 5 weeks of treatment in responders ( P =2.91×10 −2 ). Additional genetic, in vivo stress responsitivity data and murine hippocampal gene expression findings corroborate our finding of RORa as a transcriptional marker of antidepressant response. In summary, using a genome-wide transcriptomics approach and subsequent validation studies, we identified several transcripts including the circadian gene transcript RORa that may serve as biomarkers indicating antidepressant treatment response.

Ficus hirta fruits extract incorporated into an alginate-based edible coating for Nanfeng mandarin preservation

An edible coating based on 1.5% sodium alginate (SA), 0.7% citric acid and 1.0% sucrose ester with and without Ficus hirta (FH) fruit extract was applied to Nanfeng mandarins to preserve their postharvest quality. Changes in decay rate, weight loss, quality parameters, respiration rate, and enzymatic activities of the coated and control samples were assessed at 10-day intervals for a 100-day storage period at 6°C. The decay rate, weight loss, respiration rate and maleicdialdehyde (MDA) content were much lower in the FH-SA coated samples than in the control group. During the middle and later periods of storage, Nanfeng mandarin treated with FH-SA coating maintained good fruit quality. The FH-SA coating treatment enhanced the activities of antioxidant and defense-related enzymes such as superoxyde dismutase (SOD), catalase (CAT), peroxidase (POD), chitinase (CHI), β-1,3-glucanase (GLU), and phenylalanine ammonialyase (PAL), and stimulated the accumulation of phenolic compounds. Our study suggests that FH-SA coating has the potential to enhance the long term quality and storage of Nanfeng mandarin.

High level expression of Saccharomyces cerevisiae chitinase (ScCTS1) in Pichia pastoris for degrading chitin

Chitin is the second most abundant renewable biopolymer in the world. Chitinases play important roles in the degradation of chitin. Chitinases are produced by different organisms for different purposes, which are widely expressed in the three domains of life, ranging from archaea, bacteria, to fungi, yeasts, plants, insects, and even vertebrates. But there are few reports about Saccharomyces cerevisiae chitinase (ScCTS1). The aim of this study was to realize the high level expression of ScCTS1. The ScCTS1 was cloned into the expression vector pPIC9K. The recombinant plasmid was linearized and transformed into competent Pichia pastoris GS115. After screening by G418 plate, the fermentation conditions were optimized. Ultimately, under the optimal fermentation conditions, ScCTS1 enzymatic activity reached up to 94.6 U/mL. This paper presents the first report on the heterologous expression of a full-length ScCTS1 with considerably high activity. The work will not only make a great stride towards its potential applications in biotechnology, but also facilitate elucidating the precise mechanism of yeast cell division. Keywords: chitinases, heterologous expression, Saccharomyces cerevisiae, pichia pastoris, biotechnology DOI: 10.3965/j.ijabe.20150805.2071 Citation: Zhao Y X, Jiang H H, Rao Z M, Ji Y Z, Cheng Y L, Ma Y H. High level expression of Saccharomyces cerevisiae chitinase (ScCTS1) in Pichia pastoris for degrading chitin. Int J Agric & Biol Eng, 2015; 8(5): 142－150.

Biochemical , Histological Studies of Pectinophora gossypiella (Saund.) Viral Infected Larvae Supported by Scanning Electron Microscope Inspections

A lot of pink bollworm (PBW) Pectinophora gossypiella full grown larvae were excluded from cotton bolls collected from Sakha, Kafr El-Shiekh Governorate, Egypt. Larvae were transferred to laboratory of Bollworms Department, Plant Protection Research Institute, ARC, Dokki, Giza. The healthy appearance PBW larvae were placed individually in sterilized glass tubes (2x7cm) plugged with cotton wool under room conditions and observed 2 times/ week. Infected larvae with baculuviruses (NPV & GV) were collected. Present study clarified and discussed the pathogenicity of baculuviruses against PBW resting larvae in many views (appearance, histology and biochemistry). Results indicated that, the activation of PBW chitinase (CHT) at the resting period enhances the insecticidal activity of latent baculuviruses. So that the baculuviruses overcome apoptosis and prevent ecdysis of PBW resting larvae. And the scanning electron microscope and histology micrographs revealed the appearances of this infection as external scleroticzation, shrinking, swelling and internal degradation of P. gossypiella organs Furthermore, the biochemical analysis revealed decrease activity of larval chitinase with increase activity of both N-acetylglucosamine (NAG) and phenoloxidase. However, the utilizing of these epizootic baculuviruses as microbial control agents still need more studies of insect immune, insecticidal evaluation, molecular biology and environmental safety.

Use of silicon for reducing the severity of bacterial wilt of sweet pepper

Bacterial wilt of sweet pepper, caused by Ralstonia solanacearum (Rs) race 1, is a limiting disease in northern and northeastern Brazil. The present study evaluated the effect of silicon (Si) on the disease in the sweet pepper cv. Enterprise, which was grown in a substrate containing 0.00, 0.25, 0.50, 1.50, or 3.00 g SiO2 kg-1and was subsequently transplanted into soil infested with Rs CGM-8. The following variables were evaluated: latency period (LP50); incidence; bacterial wilt index (BWI); area under the disease progress curve (AUDPC); biomass; accumulation of Ca+2, Mg+2, and Si; total protein and enzymatic activity; chemical characteristics of the substrate; and in vitro bacterial growth. A dose of 2.95 g Si kg-1substrate increased the LP50 (33.6%) and reduced the BWI (98%) and AUDPC (93.7%); this treatment also increased Ca+2 levels in the shoots and reduced Mg+2levels in the shoots and the roots. Supplementation with various doses of Si yielded maximum increases in the shoot fresh biomass (121.8%), the root fresh biomass (83.6%), and the shoot dry biomass (84.9%); increased the concentrations of total protein, catalase, ascorbate peroxidase, and chitinase; caused the accumulation of Si in the shoots and substrate; increased the pH, Na+, and K+; and decreased P in the substrate. The putative mechanisms of action of Si included a direct effect on colonization of the pathogen, an indirect effect on the plant’s development, increased Ca+2 absorption, and signaled for the production of plant defence enzymes. Therefore, the production of sweet pepper seedlings in a substrate containing calcium silicate (2.95 g SiO2 kg-1) could be utilized as an alternative cultivation practice for the management of bacterial wilt disease. More research is needed to elucidate the exact mechanisms of silicon and its effects on latent infections and on bacterial cells and population.

Detection of chitinase activity and its characterization from Pseudomonas fluorescens of tea rhizosphere

&lt;div&gt;&lt;span style="color: black; line-height: 107%; font-family: 'Verdana','sans-serif'; font-size: 7.5pt; mso-bidi-language: AR-SA; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-font-family: Arial; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-GB; mso-fareast-language: EN-US;" lang="EN-GB"&gt;Please see the pdf file here: &lt;a href="http://indsocplantationcrops.in/journal.php"&gt;http://indsocplantationcrops.in/journal.php&lt;/a&gt;&lt;/span&gt;&lt;/div&gt;