Showing papers on "Chitinase published in 2023"

Chitinase-Assisted Bioconversion of Chitinous Waste for Development of Value-Added Chito-Oligosaccharides Products

Abstract: Simple Summary Bioconversion of chitinous waste to chito-oligosaccharides using chitinase is an attractive strategy for traditional waste management. Chito-oligosaccharides have a broad range of applications due to their water solubility and possess various biological properties. The different sources of chitinase provide different yields and physicochemical properties, e.g., the degree of polymerization of chito-oligosaccharides. This review discusses the potential of chitinase in chito-oligosaccharide production with a focus on the chitinase sources, chemo-enzymatic production of chito-oligosaccharides and their derivatives, applications of chito-oligosaccharides, and the route to industrialization, based on the academic studies published within the most recent decade. Abstract Chito-oligosaccharides (COSs) are the partially hydrolyzed products of chitin, which is abundant in the shells of crustaceans, the cuticles of insects, and the cell walls of fungi. These oligosaccharides have received immense interest in the last few decades due to their highly promising bioactivities, such as their anti-microbial, anti-tumor, and anti-inflammatory properties. Regarding environmental concerns, COSs are obtained by enzymatic hydrolysis by chitinase under milder conditions compared to the typical chemical degradation. This review provides updated information about research on new chitinase derived from various sources, including bacteria, fungi, plants, and animals, employed for the efficient production of COSs. The route to industrialization of these chitinases and COS products is also described.

Role of Bacillus pumilus chitinases in antifungal activity against Pseudocercospora fijiensis Morelet

Abstract: The investigation was aimed at determining the role of Bacillus pumilus CCIBP-C5 chitinases in the in vitro interaction with P. fijiensis. For this, the chitinase activity of CCIBP-C5 culture filtrate and the antifungal effect of the bacterial metabolites against Pseudocercospora fijiensis were determined from the use of a culture medium based on colloidal chitin. In all cases it was compared with the results obtained in the culture medium Nutrient Broth (NB). As a result, an increase in the production of total proteins and a greater chitinase activity was observed, as well as affectations to the mycelium and loss vitality of P. fijiensis in relation to the NB culture medium. Therefore, chitinolysis appears to be one mechanism of biological control by strain CCIBP-C5 against P. fijiensis.

Chitinase is a Potent Insecticidal Molecular Target of Camptothecin and Its Derivatives.

Abstract: Camptothecin (CPT) is a prominent molecule in natural product research because of its application prospects in medicine and agriculture. In this study, CPT and its derivatives were discovered to be competitive inhibitors of group II and group h insect chitinases, both of which are key components of insect chitinolytic systems. CPT and 7-ethyl-10-hydroxycamptothecin (SN-38) inhibited group II chitinase from Ostrinia furnacalis (OfChtII) with Ki values of 5.1 and 2.0 μM, respectively. Results from tryptophan fluorescence spectroscopy, molecular docking analysis, and molecular dynamics simulations revealed that both CPT and SN-38 inhibit OfChtII-C1 by interacting with solvent-exposed tryptophan residues in a substrate-binding cleft. CPT exhibited high insecticidal activity toward the orthopteran pest Locusta migratoria, possibly because of the midgut metabolism of CPT, with only moderate activities toward lepidopteran pests. Even though SN-38 exhibited much lower insecticidal activities than CPT, it still showed higher inhibitory activity toward chitinase. This study reports a new molecular target of CPT and provides insights into molecular design of CPT-based insecticides against different kinds of pests.

Cloning, expression and antifungal effect of the recombinant chitinase from Streptomyces sampsonii KJ40

Abstract: ABSTRACT: Streptomyces sampsonii is a kind of biocontrol bacterium with antifungal effects, and chitinase is one of the main antifungal substances. To improve and further study the structure and function of the chitinase gene of S. sampsonii, we amplified the target fragment by PCR, ligated the fragment to the expression vector pET-32a, introduced the resulting plasmid into Escherichia coli BL21 (DE3) and induced expression of the chitinase. Then, the recombinant chitinase was purified by is-labelled protein micro purification kit. A chitinase gene, Sschi61, was cloned from the genome and expressed in a prokaryote. The antifungal effect of the recombinant protein was also studied. Finally, the chitinase gene Sschi61 with a length of 1755 bp was obtained, and the expression of the 82 kDa recombinant chitinase was induced in E. coli by IPTG. The recombinant chitinase could inhibit the black spot pathogen of Eucommia ulmoides (Pestalotiopsis trachicarpicola). After the hyphae of the pathogen of black spot of Eucommia ulmoides (Pestalotiopsis trachicarpicola) were soaked with recombinant chitinase, the hyphae cells expanded, broke, and dissolved.

Localization of Pyranose 2-Oxidase from Kitasatospora aureofaciens: A Step Closer to Elucidate a Biological Role

Abstract: Lignin degradation in fungal systems is well characterized. Recently, a potential for lignin depolymerization and modification employing similar enzymatic activities by bacteria is increasingly recognized. The presence of genes annotated as peroxidases in Actinobacteria genomes suggests that these bacteria should contain auxiliary enzymes such as flavin-dependent carbohydrate oxidoreductases. The only auxiliary activity subfamily with significantly similar representatives in bacteria is pyranose oxidase (POx). A biological role of providing H2O2 for peroxidase activation and reduction of radical degradation products suggests an extracellular localization, which has not been established. Analysis of the genomic locus of POX from Kitasatospora aureofaciens (KaPOx), which is similar to fungal POx, revealed a start codon upstream of the originally annotated one, and the additional sequence was considered a putative Tat-signal peptide by computational analysis. We expressed KaPOx including this additional upstream sequence as well as fusion constructs consisting of the additional sequence, the KaPOx mature domain and the fluorescent protein mRFP1 in Streptomyces lividans. The putative signal peptide facilitated secretion of KaPOx and the fusion protein, suggesting a natural extracellular localization and supporting a potential role in providing H2O2 and reducing radical compounds derived from lignin degradation.

Insights into the ecological generalist lifestyle of Clonostachys fungi through analysis of their predicted secretomes

Abstract: Introduction The fungal secretome comprise diverse proteins that are involved in various aspects of fungal lifestyles, including adaptation to ecological niches and environmental interactions. The aim of this study was to investigate the composition and activity of fungal secretomes in mycoparasitic and beneficial fungal-plant interactions. Methods We used six Clonostachys spp. that exhibit saprotrophic, mycotrophic and plant endophytic lifestyles. Genome-wide analyses was performed to investigate the composition, diversity, evolution and gene expression of Clonostachys secretomes in relation to their potential role in mycoparasitic and endophytic lifestyles. Results and discussion Our analyses showed that the predicted secretomes of the analyzed species comprised between 7 and 8% of the respective proteomes. Mining of transcriptome data collected during previous studies showed that 18% of the genes encoding predicted secreted proteins were upregulated during the interactions with the mycohosts Fusarium graminearum and Helminthosporium solani. Functional annotation of the predicted secretomes revealed that the most represented protease family was subclass S8A (11–14% of the total), which include members that are shown to be involved in the response to nematodes and mycohosts. Conversely, the most numerous lipases and carbohydrate-active enzyme (CAZyme) groups appeared to be potentially involved in eliciting defense responses in the plants. For example, analysis of gene family evolution identified nine CAZyme orthogroups evolving for gene gains (p ≤ 0.05), predicted to be involved in hemicellulose degradation, potentially producing plant defense-inducing oligomers. Moreover, 8–10% of the secretomes was composed of cysteine-enriched proteins, including hydrophobins, important for root colonization. Effectors were more numerous, comprising 35–37% of the secretomes, where certain members belonged to seven orthogroups evolving for gene gains and were induced during the C. rosea response to F. graminearum or H. solani. Furthermore, the considered Clonostachys spp. possessed high numbers of proteins containing Common in Fungal Extracellular Membranes (CFEM) modules, known for their role in fungal virulence. Overall, this study improves our understanding of Clonostachys spp. adaptation to diverse ecological niches and establishes a basis for future investigation aiming at sustainable biocontrol of plant diseases.

Biological Control of Aspergillus flavus by the Yeast Aureobasidium pullulans In Vitro and on Tomato Fruit

Abstract: Aspergillus flavus is an important pathogenic fungus affecting many crops and is one of the main sources of their aflatoxin contamination. The primary method of limiting this pathogen is using chemical fungicides, but researchers focus on searching for other effective agents for its control due to many disadvantages and limitations of these agrochemicals. The results obtained in the present study indicate the high potential of two yeast strains, Aureobasidium pullulans PP4 and A. pullulans ZD1, in the biological control of A. flavus. Under in vitro conditions, mycelial growth was reduced by 53.61% and 63.05%, and spore germination was inhibited by 68.97% and 79.66% by ZD1 and PP4 strains, respectively. Both strains produced the lytic enzymes chitinase and β-1,3-glucanase after 5 days of cultivation with cell wall preparations (CWP) of A. flavus in the medium as a carbon source. In addition, the tested yeasts showed the ability to grow over a wide range of temperatures (4–30 °C), pH (4–11), and salinity (0–12%) and showed tolerance to fungicides at concentrations corresponding to field conditions. Both isolates tested were highly tolerant to cupric oxychloride, showing biomass gains of 85.84% (ZD1) and 87.25% (PP4). Biomass growth in the presence of fungicides azoxystrobin was 78.71% (ZD1) and 82.65% (PP4), while in the presence of difenoconazole, it was 70.09% (ZD1) and 75.25% (PP4). The yeast strains were also tested for antagonistic effects against A. flavus directly on tomato fruit. Both isolates acted effectively by reducing lesion diameter from 29.13 mm (control) to 8.04 mm (PP4) and 8.83 mm (ZD1).

Three Chitin Deacetylase Family Members of Beauveria bassiana Modulate Asexual Reproduction and Virulence of Fungi by Mediating Chitin Metabolism and Affect Fungal Parasitism and Saprophytic Life

Abstract: In this study, we report the roles of CDA family in entomopathogenic fungus B. bassiana. Our results indicated that CDA modulates asexual development and regulates fungal virulence by altering chitin deacetylation and metabolic capacity. CDA affected the biological control potential and life history of B. bassiana by affecting its parasitic and saprophytic life. These findings provide novel insights into the roles of multiple CDA paralogues existing in fungal biocontrol agents. ABSTRACT As an important chitin-modifying enzyme, chitin deacetylase (CDA) has been characterized in many fungi, but its function in the entomopathogenic fungus Beauveria bassiana remains unclear. Three CDAs with conserved domains of the carbohydrate esterase 4 (CE-4) family were identified in B. bassiana. Disruption of CDA1 resulted in growth restriction of the fungus on medium with chitin as a carbon source or without a carbon source. Deletion of CDA1 and CDA2 led to defects in fungal conidial formation and conidial vitality compared with those of the wild type (WT), and the conidial yield decreased by 25.81% to 47.68%. Inactivation of three CDA genes resulted in a decrease of 20.23% to 27% in the blastospore yield. ΔCDA1 and ΔCDA3 showed 29.33% and 23.34% reductions in cuticular infection virulence, respectively. However, the CDA family may not contribute to hemocoel infection virulence. Additionally, the sporulation of the insect carcass showed that the three gene deletion mutants were 68.45%, 63.84%, and 56.65% less than WT. Penetration experiments with cicada wings and enzyme activity assays were used to further explore the effect of the fungus on chitin metabolism after gene deletion. Although the three gene deletion mutants penetrated the cicada wings successfully and continued to grow on the underlying medium, their colony sizes were reduced by 29.12% to 47.76%. The CDA enzyme activity of ΔCDA1 and ΔCDA3 decreased by 84.76% and 83.04%, respectively. These data showed that members of the CDA family play a different role in fungal growth, conidial quality, and virulence. IMPORTANCE In this study, we report the roles of CDA family in entomopathogenic fungus B. bassiana. Our results indicated that CDA modulates asexual development and regulates fungal virulence by altering chitin deacetylation and metabolic capacity. CDA affected the biological control potential and life history of B. bassiana by affecting its parasitic and saprophytic life. These findings provide novel insights into the roles of multiple CDA paralogues existing in fungal biocontrol agents.

Activity‐based proteomics uncovers suppressed hydrolases and a <i>neo</i> ‐functionalised antibacterial enzyme at the plant–pathogen interface

Abstract: The extracellular space of plant tissues contains hundreds of hydrolases that might harm colonising microbes. Successful pathogens may suppress these hydrolases to enable disease. Here, we report the dynamics of extracellular hydrolases in Nicotiana benthamiana upon infection with Pseudomonas syringae. Using activity-based proteomics with a cocktail of biotinylated probes, we simultaneously monitored 171 active hydrolases, including 109 serine hydrolases (SHs), 49 glycosidases (GHs) and 13 cysteine proteases (CPs). The activity of 82 of these hydrolases (mostly SHs) increases during infection, while the activity of 60 hydrolases (mostly GHs and CPs) is suppressed during infection. Active β-galactosidase-1 (BGAL1) is amongst the suppressed hydrolases, consistent with production of the BGAL1 inhibitor by P. syringae. One of the other suppressed hydrolases, the pathogenesis-related NbPR3, decreases bacterial growth when transiently overexpressed. This is dependent on its active site, revealing a role for NbPR3 activity in antibacterial immunity. Despite being annotated as a chitinase, NbPR3 does not possess chitinase activity and contains an E112Q active site substitution that is essential for antibacterial activity and is present only in Nicotiana species. This study introduces a powerful approach to reveal novel components of extracellular immunity, exemplified by the discovery of the suppression of neo-functionalised Nicotiana-specific antibacterial NbPR3.

Novel Chitin Deacetylase from Thalassiosira weissflogii Highlights the Potential for Chitin Derivative Production

Abstract: β-Chitin is an important carbon fixation product of diatoms, and is the most abundant nitrogen-containing polysaccharide in the ocean. It has potential for widespread application, but the characterization of chitin-related enzymes from β-chitin producers has rarely been reported. In this study, a chitin deacetylase (TwCDA) was retrieved from the Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP) database and was heterologously expressed in vitro for functional analysis. The results showed that both the full-length sequence (TwCDA) and the N-terminal truncated sequence (TwCDA-S) had chitin deacetylase and chitinolytic activities after expression in Escherichia coli. High-performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS) indicated that TwCDA and TwCDA-S could catalyze the deacetylation of oligosaccharide (GlcNAc)5. TwCDA had higher deacetylase activity, and also catalyzed the deacetylation of the β-chitin polymer. A dinitrosalicylic acid (DNS) assay showed that TwCDA-S had high chitinolytic activity for (GlcNAc)5, and the optimal reaction temperature was 35 °C. Liquid chromatography combined with time-of-flight mass spectrometry (LC-coTOF-MS) detected the formation of a N-acetylglucosamine monomer (C8H15NO6) in the reaction mixture. Altogether, we isolated a chitin deacetylase from a marine diatom, which can catalyze the deacetylation and degradation of chitin and chitin oligosaccharides. The relevant results lay a foundation for the internal regulation mechanism of chitin metabolism in diatoms and provide a candidate enzyme for the green industrial preparation of chitosan and chitin oligosaccharides.

Physiological and Chitinase Gene Expression Responses of Male Zizania latifolia to Ustilago esculenta Infection

Abstract: This study explored the effects of Ustilago esculenta inoculation on physiological responses (activities of defense and antioxidant enzymes) and chitinase gene expression in male Zizania latifolia “jiaobai” (without U. esculenta infection, with no galls, but normal flowering). Male jiaobai seedlings were injected at the five-leaf stage with U. esculenta suspension, and the impact on transcription of several genes encoding enzymes was examined. Compared with controls, expression of most enzymes was significantly different at 3 or 12 hours postinjection, and most ZlChi genes were involved in the response to U. esculenta inoculation. Fluorescence quantitative polymerase chain reaction results showed that U. esculenta was present in the roots of male jiaobai inoculated with U. esculenta at the shoot tips. Paraffin sections revealed many fungal hyphae in the roots at 15 d after inoculation, but few in controls. The results provide a basis for further study of the responses of male Z. latifolia to U. esculenta infection.

Group h Chitinase: A Molecular Target for the Development of Lepidopteran-Specific Insecticides.

Abstract: Sustainable agriculture requires insecticides that are selective between insects and mammals and even between harmful and beneficial insects. Lepidoptera includes the largest number of insect pests that threaten crops, and Hymenoptera contains the natural enemies for these pests. Discovery of lepidopteran-specific molecular targets is one route to develop such selective pesticides. Group h chitinase (Chi-h) is an ideal target for lepidopteran-specific insecticides because it is only distributed in Lepidoptera and is critical to their molting processes. This minireview focuses on the latest progress in developing Chi-h as a lepidopteran-specific insecticide target. We describe the biological function, crystal structure, and small-molecule inhibitors of the enzyme. Notably, two unique pockets were discovered in the crystal structure of Chi-h for the binding of the selective inhibitors, phlegmacin B1 and lynamicin B. Moreover, lynamicin B was found to exhibit significant insecticidal activity toward lepidopteran pests but is harmless toward their natural enemies. These findings are advancing the development of selective insecticides to meet the needs of sustainable agriculture.

Prospects of chitinase in sustainable farming and modern biotechnology: an update on recent progress and challenges.

Abstract: Chitinases are multifunctional biocatalysts for the pest control and useful in modern biotechnology and pharmaceutical industries. Chemical-based fungicides and insecticides have caused more severe effects on environment and human health. Many pathogenic fungal species and insects became resistant to the chemical pesticides. The resistant fungi emerged as a multidrug resistant also and less susceptible insects are not possible to control adequately. Chitinases have an immense potential to be exploited as a biopesticide against fungi and insects. The direct use of chitinase in liquid formulation or whole microbial enzyme producing cells, both act as antagonistically against the pests. Chitinase can disintegrate the fungal cell wall and insect integument that holds the chitin as a vital structural component. Moreover, chitinase is applied for the synthesis of pharmaceutically important chitooligosaccharides. Chitinase producing microbes have the huge potential to utilize against the waste management of sea food remains like shells of crustaceans. Chitinase is valuable for the synthesis of protoplasts from industrially important fungi, further it act as the biocontrol agent of malaria and dengue fever causing larvae of mosquitoes. Chitinases also have been successfully used in wine and single cell protein producing industries. Present review is illustrating the updated information on the state of the art of different applications of chitinases in agriculture and biotechnology industry. It also bestows the understanding to the readers about the areas of extensively studied and the field where there is still much left to be done.

Exploring the Biocontrol Efficacy of Trichoderma spp. against Rigidoporus microporus, the Causal Agent of White Root Rot Disease in Rubber Trees (Hevea brasiliensis)

Abstract: Rigidoporus microporus, which causes white root rot disease (WRD) in Hevea brasiliensis, is a looming threat to rubber plantation in Malaysia. The current study was conducted to determine and evaluate the efficiency of fungal antagonists (Ascomycota) against R. microporus in rubber trees under laboratory and nursery conditions. A total of 35 fungal isolates established from the rubber tree rhizosphere soil were assessed for their antagonism against R. microporus by the dual culture technique. Trichoderma isolates can inhibit the radial growth of R. microporus by 75% or more in the dual culture test. Strains of T. asperellum, T. koningiopsis, T. spirale, and T. reesei were selected to assess the metabolites involved in their antifungal activity. Results indicated that T. asperellum exhibited an inhibitory effect against R. microporus in both volatile and non-volatile metabolite tests. All Trichoderma isolates were then tested for their ability in producing hydrolytic enzymes such as chitinase, cellulase and glucanase, indole acetic acid (IAA), siderophores production, and phosphate solubilization. From the positive results of the biochemical assays, T. asperellum and T. spirale were selected as the biocontrol candidates to be further tested in vivo against R. microporus. The nursery assessments revealed that rubber tree clone RRIM600 pretreated with only T. asperellum or with the combination of T. asperellum and T. spirale was able to reduce the disease severity index (DSI) and exert higher suppression of R. microporus compared to other pretreated samples, with the average DSI below 30%. Collectively, the present study demonstrates that T. asperellum represents a potential biocontrol agent that should be further explored to control R. microporus infection on rubber trees.

Irreversible evolutionary loss of chitin‐degrading ability in the chitinase‐like protein Ym1 under positive selection in rodents

Abstract: Ym1 (chitinase‐like 3, Chil3) expressed in mice is a nonenzymatic chitinase‐like protein, which shows 67% identity with mouse acidic chitinase (Chia). Similar to Chia, Ym1 is overexpressed in asthma and parasitic infections in mouse lungs. Due to the lack of chitin‐degrading activity, the biomedical role of Ym1 under these pathophysiological conditions remains to be determined. In this study, we investigated what region and amino acid changes in Ym1 resulted in the loss of enzymatic activity. Replacing two amino acids at the catalytic motif to obtain a Chia‐like sequence (N136D and Q140E; MT‐Ym1) did not activate the protein. We conducted a comparative study of Ym1 and Chia. We found that three protein segments—(i) the catalytic motif residues, (ii) exons 6 and 7, and (iii) exon 10—are responsible for chitinase activity loss in Ym1. We show that replacing each of these three segments in Chia that are also involved in substrate recognition and binding by the Ym1 sequence can fully abolish the enzymatic activity. In addition, we show that there have been extensive gene duplication events at the Ym1 locus specific to the rodent lineages. Consistent with this result, Ym1 orthologs from the rodent genome were under positive selection when analyzed through the CODEML program. These data suggest that numerous amino acid substitutions in the regions involved in the chitin recognition, binding, and degradation ability of the ancestor Ym1 molecule lead to the irreversible inactivation of the protein.

Inhibition of Macrophage-Specific CHIT1 as an Approach to Treat Airway Remodeling in Severe Asthma

Abstract: Chitotriosidase (CHIT1) is an enzyme produced by macrophages that regulates their differentiation and polarization. Lung macrophages have been implicated in asthma development; therefore, we asked whether pharmacological inhibition of macrophage-specific CHIT1 would have beneficial effects in asthma, as it has been shown previously in other lung disorders. CHIT1 expression was evaluated in the lung tissues of deceased individuals with severe, uncontrolled, steroid-naïve asthma. OATD-01, a chitinase inhibitor, was tested in a 7-week-long house dust mite (HDM) murine model of chronic asthma characterized by accumulation of CHIT1-expressing macrophages. CHIT1 is a dominant chitinase activated in fibrotic areas of the lungs of individuals with fatal asthma. OATD-01 given in a therapeutic treatment regimen inhibited both inflammatory and airway remodeling features of asthma in the HDM model. These changes were accompanied by a significant and dose-dependent decrease in chitinolytic activity in BAL fluid and plasma, confirming in vivo target engagement. Both IL-13 expression and TGFβ1 levels in BAL fluid were decreased and a significant reduction in subepithelial airway fibrosis and airway wall thickness was observed. These results suggest that pharmacological chitinase inhibition offers protection against the development of fibrotic airway remodeling in severe asthma.

Crystal structure of a polyglycine hydrolase determined using a <i>RoseTTAFold</i> model

Abstract: Polyglycine hydrolases (PGHs) are secreted fungal proteases that cleave the polyglycine linker of Zea mays ChitA, a defensive chitinase, thus overcoming one mechanism of plant resistance to infection. Despite their importance in agriculture, there has been no previous structural characterization of this family of proteases. The objective of this research was to investigate the proteolytic mechanism and other characteristics by structural and biochemical means. Here, the first atomic structure of a polyglycine hydrolase was identified. It was solved by X-ray crystallography using a RoseTTAFold model, taking advantage of recent technical advances in structure prediction. PGHs are composed of two domains: the N- and C-domains. The N-domain is a novel tertiary fold with an as-yet unknown function that is found across all kingdoms of life. The C-domain shares structural similarities with class C β-lactamases, including a common catalytic nucleophilic serine. In addition to insights into the PGH family and its relationship to β-lactamases, the results demonstrate the power of complementing experimental structure determination with new computational techniques.

Amanita sp. from subtropical region of Saudi Arabia as a source of chitinase enzyme and its antifungal activity

Abstract: Mushroom products have been used as a biotechnological tool for many applications. Particularly, thermostable chitinase plays a vital role in biowaste management and biological control. In the present investigation, Amanita sp. was recorded in the subtropical region of Saudi Arabia, therefore, it was utilized for chitinase production using substrates chitin and dead fungal mycelia (DFM). Compared with the DFM, chitin was more suitable for chitinase activity at different temperatures and pH. Amanita sp. produced chitinase up to 70 °C, but the optimum was 50 °C. The chitinase activity was 4.98, 3.5, and 0.9 U.mg-1 with the use of chitin, while it was 4.6, 3.1, and 0.6 U.mg-1 with the use of DFM at 50, 60, and 70 °C, respectively. Chitinase activity was stable up to 60 °C, then it began to decrease at 70 °C. The chitinase activity was better at pH 4 and 5 than pH 8 and 9. The antifungal effect of the produced chitinase at 50 °C was more effective than at 60 °C. For instance, the Alternaria alternata colony radius was 3.50 cm and 2.26 cm at 50 °C while it was 4.35 cm and 4.13 cm at 60 °C when using DFM and chitin, respectively.

Pathogenesis-Related Proteins (PRs) with Enzyme Activity Activating Plant Defense Responses

Abstract: Throughout evolution, plants have developed a highly complex defense system against different threats, including phytopathogens. Plant defense depends on constitutive and induced factors combined as defense mechanisms. These mechanisms involve a complex signaling network linking structural and biochemical defense. Antimicrobial and pathogenesis-related (PR) proteins are examples of this mechanism, which can accumulate extra- and intracellular space after infection. However, despite their name, some PR proteins are present at low levels even in healthy plant tissues. When they face a pathogen, these PRs can increase in abundance, acting as the first line of plant defense. Thus, PRs play a key role in early defense events, which can reduce the damage and mortality caused by pathogens. In this context, the present review will discuss defense response proteins, which have been identified as PRs, with enzymatic action, including constitutive enzymes, β-1,3 glucanase, chitinase, peroxidase and ribonucleases. From the technological perspective, we discuss the advances of the last decade applied to the study of these enzymes, which are important in the early events of higher plant defense against phytopathogens.

Molecular identification of the chitinase genes in Aedes albopictus and essential roles of AaCht10 in pupal-adult transition

Abstract: Abstract Background Aedes albopictus is an increasingly serious threat in public health due to it is vector of multiple arboviruses that cause devastating human diseases, as well as its widening distribution in recent years. Insecticide resistance is a serious problem worldwide that limits the efficacy of chemical control strategies against Ae. albopictus . Chitinase genes have been widely recognized as attractive targets for the development of effective and environmentally safe insect management measures. Methods Chitinase genes of Ae . albopictus were identified and characterized on the basis of bioinformatics search of the referenced genome. Gene characterizations and phylogenetic relationships of chitinase genes were investigated, and spatio-temporal expression pattern of each chitinase gene was evaluated using qRT-PCR. RNA interference (RNAi) was used to suppress the expression of AaCht 10, and the roles of AaCht 10 were verified based on phynotype observations, chitin content analysis and hematoxylin and eosin (H&E) stain of epidermis and midgut. Results Altogether, 14 chitinase-related genes (12 chitinase genes and 2 IDGF s) encoding 17 proteins were identified. Phylogenetic analysis showed that all these AaCht s were classified into seven groups, and most of them were gathered into group IX. Only AaCht 5-1, AaCht 10 and AaCht 18 contained both catalytic and chitin-binding domains. Different AaCht s displayed development- and tissue-specific expression profiling. Suppression of the expression of AaCht 10 resulted in abnormal molting, increased mortality, decreased chitin content and thinning epicuticle, procuticle and midgut wall of pupa. Conclusions Findings of the present study will aid in determining the biological functions of AaCht s and also contribute to using AaCht s as potential target for mosquito management. Graphical Abstract