Chitin Treatment Research Articles

Gene Editing a Constitutively Active OsRac1 by Homologous Recombination-Based Gene Targeting Induces Immune Responses in Rice

OsRac1 is a member of the plant small GTPase Rac/Rop family and plays a key role in rice immunity. The constitutively active (CA) G19V mutation of OsRac1 was previously shown to induce reactive oxygen species production, phytoalexin synthesis and defense gene activation, leading to resistance to rice blast infection. To study further the effect of the G19V mutation in disease resistance, we introduced a single base substitution by gene targeting and removed the selectable marker using Cre-loxP site-specific recombination. The CA-OsRac1 gene generated by gene targeting was termed CA-gOsRac1. The G19V mutation was transferred from a targeting vector to the OsRac1 locus and stably transmitted to the next generation. In the leaf blade of homozygous CA-gOsRac1 plants, mutant transcript levels were much lower than in those of wild-type plants. In contrast, mutant transcripts in roots, leaf sheaths and panicles were more abundant than those in leaf blades. However, upon chitin treatment, the expression of defense-related genes PAL1 and PBZ1 in the cell culture was greater in the mutants compared with wild-type plants. Furthermore, induction of hypersensitive response (HR)-like cell death was observed in the leaf sheaths of mutant plants infected with a compatible race of rice blast fungus. In the CA-gOsRac1 plants, a number of genes previously shown to be induced by Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae (Xoo) infection were induced in the leaf sheath without pathogen infection. These results suggest that gene targeting will provide mutations useful for gene function studies and crop improvement.

OsRap2.6 transcription factor contributes to rice innate immunity through its interaction with Receptor for Activated Kinase-C 1 (RACK1)

BackgroundThe rice small GTPase OsRac1 is a molecular switch in rice innate immunity. The Receptor for Activated Kinase C-1 (RACK1) interacts with OsRac1 to suppress the growth of the rice blast fungus, Magnaporthe oryzae. RACK1 has two homologs in rice, RACK1A and RACK1B. Overexpressing RACK1A enhances resistance to the rice blast fungus. However, RACK1A downstream signals are largely unknown.ResultsHere, we report the identification of OsRap2.6, a transcription factor that interacts with RACK1A. We found a 94% similarity between the OsRap2.6 AP2 domain and Arabidopsis Rap2.6 (AtRap2.6). Bimolecular fluorescence complementation (BiFC) assays in rice protoplasts using tagged OsRap2.6 and RACK1A with the C-terminal and N-terminal fragments of Venus (Vc/Vn) indicated that OsRap2.6 and RACK1A interacted and localized in the nucleus and the cytoplasm. Moreover, OsRap2.6 and OsMAPK3/6 interacted in the nucleus and the cytoplasm. Expression of defense genes PAL1 and PBZ1 as well as OsRap2.6 was induced after chitin treatment. Disease resistance analysis using OsRap2.6 RNAi and overexpressing (Ox) plants infected with the rice blast fungus indicated that OsRap2.6 RNAi plants were highly susceptible, whereas OsRap2.6 Ox plants had an increased resistance to the compatible blast fungus.ConclusionsOsRap2.6 contributes to rice innate immunity through its interaction with RACK1A in compatible interactions.Electronic supplementary materialThe online version of this article (doi:10.1186/1939-8433-5-35) contains supplementary material, which is available to authorized users.

Effect of γ-irradiation on the thermomechanical and morphological properties of chitosan obtained from prawn shell: Evaluation of potential for irradiated chitosan as plant growth stimulator for Malabar spinach

In the present study we have synthesized chitosan from waste prawn shell via γ-irradiation of chitin and subsequent alkaline treatment. The detailed experimental studies demonstrated that nonirradiated chitin deacetylated by 40% NaOH solution showed 72% degree of deacetylation (DD), however 50kGy irradiated chitin, deacetylated by 20% NaOH demonstrated 81.5% DD. Chitosan in solid state as obtained from γ-irradiation of chitin was further irradiated by different doses (2–100kGy) of gamma irradiation and the effects of irradiation on the molecular weight, thermo-mechanical by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and antimicrobial properties were evaluated with respect to nonirradiated chitosan sample. Gamma irradiation of chitosan with a dose of 100kGy caused a decrease in average molecular weight from 1.9×105 to 6.5×104Da and thus increased its solubility in water. Nonirradiated and γ-irradiated chitosan at concentration 1% (w/w) in water were prepared and used to evaluate of its potentiality for growth stimulation of Malabar spinach. The chitosan solution was sprayed on the specimen plants and neighboring soil where germinations were taken place and various plant growth parameters such as plant height, number of leaves, leaf areas, dry and wet weight of the plants and roots were investigated. The details study revealed that application of 30kGy irradiated chitosan yielded 60% higher growth of the Malabar spinach than that obtained from nonirradiated chitosan. The data are consistent with preliminary results from field experiments and unambiguously confirms that a minor amount of chitosan has a profound effect on the growth and development of Malabar spinach.

LYK4, a Lysin Motif Receptor-Like Kinase, Is Important for Chitin Signaling and Plant Innate Immunity in Arabidopsis

Chitin is commonly found in fungal cell walls and is one of the well-studied microbe/pathogen-associated molecular patterns. Previous studies showed that lysin motif (LysM)-containing proteins are essential for plant recognition of chitin, leading to the activation of plant innate immunity. In Arabidopsis (Arabidopsis thaliana), the LYK1/CERK1 (for LysM-containing receptor-like kinase1/chitin elicitor receptor kinase1) was shown to be essential for chitin recognition, whereas in rice (Oryza sativa), the LysM-containing protein, CEBiP (for chitin elicitor-binding protein), was shown to be involved in chitin recognition. Unlike LYK1/CERK1, CEBiP lacks an intracellular kinase domain. Arabidopsis possesses three CEBiP-like genes. Our data show that mutations in these genes, either singly or in combination, did not compromise the response to chitin treatment. Arabidopsis also contains five LYK genes. Analysis of mutations in LYK2, -3, -4, or -5 showed that LYK4 is also involved in chitin signaling. The lyk4 mutants showed reduced induction of chitin-responsive genes and diminished chitin-induced cytosolic calcium elevation as well as enhanced susceptibility to both the bacterial pathogen Pseudomonas syringae pv tomato DC3000 and the fungal pathogen Alternaria brassicicola, although these phenotypes were not as dramatic as that seen in the lyk1/cerk1 mutants. Similar to LYK1/CERK1, the LYK4 protein was also localized to the plasma membrane. Therefore, LYK4 may play a role in the chitin recognition receptor complex to assist chitin signal transduction and plant innate immunity.

Ethylene-Responsive Element-Binding Factor 5, ERF5, Is Involved in Chitin-Induced Innate Immunity Response

Our recent work demonstrated that chitin treatment modulated the expression of 118 transcription factor (TF) genes in Arabidopsis. To investigate the potential roles of these TF in chitin signaling and plant defense, we initiated an interaction study among these TF proteins, as well as two chitin-activated mitogen-activated protein kinases (MPK3 and MPK6), using a yeast two-hybrid system. This study revealed interactions among the following proteins: three ethylene-responsive element-binding factors (ERF), five WRKY transcription factors, one scarecrow-like (SCL), and the two MPK, in addition to many other interactions, reflecting a complex TF interaction network. Most of these interactions were subsequently validated by other methods, such as pull-down and in planta bimolecular fluorescence complementation assays. The key node ERF5 was shown to interact with multiple proteins in the network, such as ERF6, ERF8, and SCL13, as well as MPK3 and MPK6. Interestingly, ERF5 appeared to negatively regulate chitin signaling and plant defense against the fungal pathogen Alternaria brassicicola and positively regulate salicylic acid signaling and plant defense against the bacterial pathogen Pseudomonas syringae pv. tomato DC3000. Therefore, ERF5 may play an important role in plant innate immunity, likely through coordinating chitin and other defense pathways in plants in response to different pathogens.

Induction of proinflammatory mediators by CHI3L1 is reduced by chitin treatment: Decreased tumor metastasis in a breast cancer model

Disseminated metastasis accounts for over 90% of breast cancer deaths. Recently, elevated serum levels of a glycoprotein known as chitinase-3 like-protein-1 (CHI3L1) has been correlated with poor prognosis and shorter survival of patients with metastatic breast cancer. In this study, we show that there are increased levels of CHI3L1 in plasma of tumor-bearing mice and that both tumor cells and immune cells express and secrete CHI3L1. However, the biological and physiological functions of CHI3L1 are still unclear. We demonstrate that while CHI3L1 has an inhibitory role in the expression of interferon-gamma (IFN-γ), CHI3L1 up-regulates pro-inflammatory mediators, C-chemokine ligand 2 (CCL2), chemokine CX motif ligand 2 (CXCL2) and matrix metalloproteinase-9 (MMP-9) all of which contribute to tumor growth and metastasis. We found that in vitro inhibition of CHI3L1 by siRNA suppressed the production of CCL2, CXCL2 and MMP-9 by macrophages. In vivo treatment of mammary tumor-bearing mice with chitin (β-(1-4)-poly-N-acetyl D-glucosamine), a TH(1) adjuvant and a ligand for CHI3L1, promoted immune effector functions with increased production of IFN-γ and decreased CCL2, CXCL2 and MMP-9 expression. In vivo administration of chitin to mammary tumor-bearing mice significantly decreased lung metastasis. These studies show that CHI3L1 plays a role in tumor progression and that chitin can inhibit the pleiotropic effects of CHI3L1 giving support to the idea that CHI3L1 is a useful therapeutic target for treatment of breast cancer.

Marine microbial community response to inorganic and organic sediment amendments in laboratory mesocosms

Sediment amendments provide promising strategies of enhancing sequestration of heavy metals and degradation of organic contaminants. The impacts of sediment amendments for metal and organic remediation including apatite, organoclay (and apatite and organoclay in geotextile mats), acetate, and chitin on environmental microbial communities in overlying water and sediment profiles are reported here. These experiments were performed concurrent with an ecotoxicity evaluation (data submitted in companion paper) and X-ray absorption spectroscopy of zinc speciation post apatite amendments. X-ray absorption spectra showed that a modest modification of zinc speciation occurred in amended treatments. Significant changes in both bacterial cell densities and populations were observed in response to amendments of apatite+organoclay, chitin, and acetate. The enriched bacteria and breakdown of these amendments were likely attributed to water quality degradation (e.g. ammonia and dissolved oxygen). Molecular fingerprints of bacterial communities by denaturant gradient gel electrophoresis (DGGE) showed that distinct bacterial populations occurred in overlying waters from different amendments: apatite+organoclay led to the dominance of Gammaproteobacteria, acetate enriched Alphaproteobacteria, and chitin treatment led to a dominance of Bacteroidetes and Alphaproteobacteria. In amended sediments, Firmicutes, Bacteroidetes, and Deltaproteobacteria ( Desulfovibrio) were commonly found with chitin and apatite+chitin treatments. Finally, sulfate-reducing bacteria (e.g. Desulfovibrio) and metal-reducing bacteria were also recovered with most probable number (MPN) analyses in treatments with acetate, chitin, and apatite+chitin. These geochemically important bacteria were stimulated by amendments and may play critical functional roles in the metal and organic contaminant remediation process for future investigations of contaminated sediments.

ATL9, a RING Zinc Finger Protein with E3 Ubiquitin Ligase Activity Implicated in Chitin- and NADPH Oxidase-Mediated Defense Responses

Pathogen associated molecular patterns (PAMPs) are signals detected by plants that activate basal defenses. One of these PAMPs is chitin, a carbohydrate present in the cell walls of fungi and in insect exoskeletons. Previous work has shown that chitin treatment of Arabidopsis thaliana induced defense-related genes in the absence of a pathogen and that the response was independent of the salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) signaling pathways. One of these genes is ATL9 ( = ATL2G), which encodes a RING zinc-finger like protein. In the current work we demonstrate that ATL9 has E3 ubiquitin ligase activity and is localized to the endoplasmic reticulum. The expression pattern of ATL9 is positively correlated with basal defense responses against Golovinomyces cichoracearum, a biotrophic fungal pathogen. The basal levels of expression and the induction of ATL9 by chitin, in wild type plants, depends on the activity of NADPH oxidases suggesting that chitin-mediated defense response is NADPH oxidase dependent. Although ATL9 expression is not induced by treatment with known defense hormones (SA, JA or ET), full expression in response to chitin is compromised slightly in mutants where ET- or SA-dependent signaling is suppressed. Microarray analysis of the atl9 mutant revealed candidate genes that appear to act downstream of ATL9 in chitin-mediated defenses. These results hint at the complexity of chitin-mediated signaling and the potential interplay between elicitor-mediated signaling, signaling via known defense pathways and the oxidative burst.

Evolution and Regulation of the Lotus japonicus LysM Receptor Gene Family

LysM receptor kinases were identified as receptors of acylated chitin (Nod factors) or chitin produced by plant-interacting microbes. Here, we present the identification and characterization of the LysM receptor kinase gene (Lys) family (17 members) in Lotus japonicus. Comprehensive phylogenetic analysis revealed a correlation between Lys gene structure and phylogeny. Further mapping coupled with sequence-based anchoring on the genome showed that the family has probably expanded by a combination of tandem and segmental duplication events. Using a sliding-window approach, we identified distinct regions in the LysM and kinase domains of recently diverged Lys genes where positive selection may have shaped ligand interaction. Interestingly, in the case of NFR5 and its closest paralog, LYS11, one of these regions coincides with the predicted Nod-factor binding groove and the suggested specificity determining area of the second LysM domain. One hypothesis for the evolutionary diversification of this receptor family in legumes is their unique capacity to decipher various structures of chitin-derived molecules produced by an extended spectrum of interacting organisms: symbiotic, associative, endophytic, and parasitic. In a detailed expression analysis, we found several Lotus Lys genes regulated not only during the symbiotic association with Mesorhizobium loti but also in response to chitin treatment.

One bath method dyeing of polyester/cotton blend fabric with sulphatoethylsulphonyl disperse/reactive dyes treatment by chitin biopolymer

In this research, the process of dyeing polyester/cotton fabrics using disperse/reactive dyestuffs in one method dyeing processes was investigated. In the order to improve the adhesion of chitin to the surface of polyester/cotton fibers, pre-treatment in NaOH solutions was performed. The colour and rubbing fastness properties of the chitin-deposited polyester/cotton fabrics were assessed. The colour difference between the dyed blank samples and samples dyed in NaOH and/or different viscosity chitin treatment was estimated. The data obtained shows that it is possible to dye polyester/cotton fabrics finished by chitin with only one disperses/reactive dyestuff. The dyed samples showed good rubbing and washing colour fastness properties within the range of colour change. The colour strength of the dyed samples increased with the increased deposition of chitin on the fabric.

One bath method dyeing of polyester/cotton blend fabric with sulphatoethylsulphonyl disperse/reactive dyes treatment by chitin biopolymer

In this research, the process of dyeing polyester/cotton fabrics using disperse/reactive dyestuffs in one method dyeing processes was investigated. In the order to improve the adhesion of chitin to the surface of polyester/cotton fibers, pre-treatment in NaOH solutions was performed. The colour and rubbing fastness properties of the chitin-deposited polyester/cotton fabrics were assessed. The colour difference between the dyed blank samples and samples dyed in NaOH and/or different viscosity chitin treatment was estimated. The data obtained shows that it is possible to dye polyester/cotton fabrics finished by chitin with only one disperses/reactive dyestuff. The dyed samples showed good rubbing and washing colour fastness properties within the range of colour change. The colour strength of the dyed samples increased with the increased deposition of chitin on the fabric.

Evaluation of the Effect of Ecologic on Root Knot Nematode, Meloidogyne incognita, and Tomato Plant, Lycopersicon esculenum

Nonchemical methods and strategies for nematode management including cultural methods and engineered measures have been recommended as an alternative to methyl bromide (a major soil fumigant), due to its role in the depletion of the ozone layer. Hence, an international agreement has recently been reached calling for its reduced consumption and complete phasing out. This present research evaluates the potential of Ecologic, a biological, marine shell meal chitin material, as a soil amendment management agent for root knot nematode, Meloidogyne incognita, control, and its effect on the growth of Floradel tomato plant, Lycopersicon esculentum. To accomplish this goal, studies were conducted during which, experimental pots were set up in greenhouse environments using sterilized soil inoculated with 5,000 root-knot eggs per 1500 g soil. There were 4 treatments and 5 replications. Treatments were: No chitin; 50 g chitin; 100 g chitin; and 200 g chitin. A two-week wait period following Ecologic amendment preceded Floradel tomato planting to allow breakdown of the chitin material into the soil. Fresh and dry weights of shoot and root materials were taken as growth end-points. A statistically significant difference (p < or = 0.05) was obtained with regard to the growth rate of L. esculentum at 100 g chitin treatment compared to the control with no chitin. Mean fresh weights of Floradel tomato were 78.0 +/- 22.3 g, 81.0 +/- 20.3 g, 109.0 +/- 25.4 g and 102.0 +/- 33.3 g at 0, 50, 100 and 200 g chitin, respectively. The analysis of root knot nematode concentrations indicated a substantial effect on reproduction rate associated with chitin amendment. Study results showed a significant decrease in both root knot nematode eggs and juveniles (J2) at 100g and 200 g Ecologic chitin levels, however, an increase in nematode concentrations was recorded at the 50 g Ecologic chitin level (p < or = 0.05). The mean amounts of J2 population, as expressed per 1500 cm3 soil, were 49,933 +/- 38,819, 86,050 +/- 25248, 103 +/- 133 and 103 +/- 133 for 0, 50, 100 and 200 g chitin, respectively. Similarly, the mean numbers of root knot nematode eggs (per 1500 cm3 of soil) were 40,759 +/- 36,712, 66,048 +/- 39,730, 9,904 +/- 16,591 and 9,257 +/- 17,204. Root gall rating was also significantly lower (p < or = 0.05) at the 100 g and 200 g chitin levels compared to the control. Percent gall ratings were 3.3 +/- 1.0%, 3.2 +/- 1.0%, 1.0 +/- 0.5%, and 1.0% +/- 0.6% for amendment levels of 0, 50, 100, and 200 g chitin, respectively.

Evaluation of the Effect of Ecologic on Root Knot Nematode, Meloidogyne incognita, and Tomato Plant, Lycopersicon esculenum

Nonchemical methods and strategies for nematode management including cultural methods and engineered measures have been recommended as an alternative to methyl bromide (a major soil fumigant), due to its role in the depletion of the ozone layer. Hence, an international agreement has recently been reached calling for its reduced consumption and complete phasing out. This present research evaluates the potential of Ecologic, a biological, marine shell meal chitin material, as a soil amendment management agent for root knot nematode, Meloidogyne incognita, control, and its effect on the growth of Floradel tomato plant, Lycopersicon esculentum. To accomplish this goal, studies were conducted during which, experimental pots were set up in greenhouse environments using sterilized soil inoculated with 5,000 root-knot eggs per 1500 g soil. There were 4 treatments and 5 replications. Treatments were: No chitin; 50 g chitin; 100 g chitin; and 200 g chitin. A two-week wait period following Ecologic amendment preceded Floradel tomato planting to allow breakdown of the chitin material into the soil. Fresh and dry weights of shoot and root materials were taken as growth end-points. A statistically significant difference (p ≤ 0.05) was obtained with regard to the growth rate of L. esculentum at 100 g chitin treatment compared to the control with no chitin. Mean fresh weights of Floradel tomato were 78.0 ± 22.3g, 81.0 ± 20.3g, 109.0 ± 25.4g and 102.0 ± 33.3g at 0, 50, 100 and 200g chitin, respectively. The analysis of root knot nematode concentrations indicated a substantial effect on reproduction rate associated with chitin amendment. Study results showed a significant decrease in both root knot nematode eggs and juveniles (J2) at 100g and 200g Ecologic chitin levels, however, an increase in nematode concentrations was recorded at the 50g Ecologic chitin level (p ≤ 0.05). The mean amounts of J2 population, as expressed per 1500cm3 soil, were 49,933 ± 38,819, 86,050 ± 25248, 103 ± 133 and 103 ± 133 for 0, 50, 100 and 200g chitin, respectively. Similarly, the mean numbers of root knot nematode eggs (per 1500cm3 of soil) were 40,759 ± 36,712, 66,048 ± 39,730, 9,904 ± 16,591 and 9,257 ± 17,204. Root gall rating was also significantly lower (p ≤ 0.05) at the 100g and 200g chitin levels compared to the control. Percent gall ratings were 3.3 ± 1.0%, 3.2 ± 1.0%, 1.0 ± 0.5%, and 1.0% ± 0.6% for amendment levels of 0, 50, 100, and 200g chitin, respectively.

Identification of 118 Arabidopsis Transcription Factor and 30 Ubiquitin-Ligase Genes Responding to Chitin, a Plant-Defense Elicitor

Chitin, found in the cell walls of true fungi and the exoskeleton of insects and nematodes, is a well-established elicitor of plant defense responses. In this study, we analyzed the expression patterns of Arabidopsis thaliana transcription factor (TF) and ubiquitin-ligase genes in response to purified chitooctaose at different treatment times (15, 30, 60, 90, and 120 min after treatment), using both quantitative polymerase chain reaction and the Affymetrix Arabidopsis whole-genome array. A total of 118 TF genes and 30 ubiquitin-ligase genes were responsive to the chitin treatment. Among these genes, members from the following four TF families were overrepresented: APETALA2/ethylene-reponsive element binding proteins (27), C2H2 zinc finger proteins (14), MYB domain-containing proteins (11), and WRKY domain transcription factors (14). Transcript variants from a few of these genes were found to respond differentially to chitin, suggesting transcript-specific regulation of these TF genes.

Expression of rice Ca 2+-dependent protein kinases (CDPKs) genes under different environmental stresses

Ca 2+-dependent protein kinases (CDPKs) play an essential role in plant Ca 2+-mediated signal transduction. Twenty-nine CDPK genes have been identified in the rice genome through a complete search of genome and full-length cDNA databases. Eight of them were reported previously to be inducible by different stress stimuli. Sequence comparison revealed that all 29 CDPK genes ( OsCPK1-29) contain multiple stress-responsive cis-elements in the promoter region (1 kb) upstream of genes. Analysis of the information extracted from the Rice Expression Database indicates that 11 of the CDPK genes are regulated by chilling temperature, dehydration, salt, rice blast infection and chitin treatment. RT-PCR and RNA gel blot hybridization were performed in this study to detect the expression 19 of the CDPK genes. Twelve CDPK genes exhibited cultivar- and tissue-specific expression; four CDPK genes ( OsCPK6, OsCPK13, OsCPK17 and OsCPK25) were induced by chilling temperature, dehydration and salt stresses in the rice seedlings. While OsCPK13 ( OsCDPK7) was already known to be inducible by chilling temperature and high salt, this is the first report that the other three genes are stress-regulated. OsCPK6 and OsCPK25 are up-regulated by dehydration and heat shock, respectively, while OsCPK17 is down-regulated by chilling temperature, dehydration and high salt stresses. Based on this evidence, rice CDPK genes may be important components in the signal transduction pathways for stress responses. Findings from this research are important for further dissecting mechanisms of stress response and functions of CDPK genes in rice.

Removal of wheat-germ agglutinin increases protein synthesis in wheat-germ extracts.

Affinity chromatography of wheat germ extracts on a chitin column increased the rate and extent of protein synthesis, programmed by rabbit globin mRNA. Addition of purified wheat germ agglutinin to the chitin-treated extract reduced the rate of protein synthesis to about the levels seen in the untreated extracts. Experiments where the ratio of messenger to extract and the ratio of supernatant to ribosomes were varied, indicated that addition of wheat germ agglutinin reduced the amount of available ribosomes. Reduced and carboxymethylated wheat germ agglutinin failed to inhibit protein synthesis and was unable to bind to the ribosomes. However, labelled intact agglutinin was found to be bound to ribosomes. The bound agglutinin was not released by acid treatment. The inhibiting effect of wheat germ, agglutinin on protein synthesis could not be counteracted by addition of N-acetyl-D-glucosamine or sialic acid, whereas thiols partially diminished the inhibition. The data indicate that wheat germ agglutinin binds reversibly to ribosomes, probably through mixed disulfide formation, and that chitin treatment increases the ability of wheat germ extracts to support protein synthesis, at least in part, by removing the wheat germ agglutinin. The possibility that chitin treatment also removed other inhibitors of protein synthesis cannot be excluded.

Microbially induced defense related proteins against postharvest anthracnose infection in mango

The talc based formulation of plant growth promoting rhizobacteria (PGPR) and yeast antagonistic strains with or without chitin amendment was evaluated against anthracnose in mango. A preharvest application of Pseudomonas fluorescens (FP7) with chitin formulation at monthly spray intervals through aerial spray significantly reduced the pre and postharvest anthracnose incidence. The strain FP7 containing chitin treated mango tree revealed the maximum panicle initiation and yield attributes. In field trials, P. fluorescens (FP7)+chitin treatment reduced the anthracnose incidence of 60% over untreated control and its efficacy was superior to standard fungicide carbendazim treatment. The reduced latent symptom expression was noticed in stored conditions.

Microbially induced defense related proteins against postharvest anthracnose infection in mango

The talc based formulation of plant growth promoting rhizobacteria (PGPR) and yeast antagonistic strains with or without chitin amendment was evaluated against anthracnose in mango. A preharvest application of Pseudomonas fluorescens (FP7) with chitin formulation at monthly spray intervals through aerial spray significantly reduced the pre and postharvest anthracnose incidence. The strain FP7 containing chitin treated mango tree revealed the maximum panicle initiation and yield attributes. In field trials, P. fluorescens (FP7)+chitin treatment reduced the anthracnose incidence of 60% over untreated control and its efficacy was superior to standard fungicide carbendazim treatment. The reduced latent symptom expression was noticed in stored conditions.

Lytic enzymes induced by Pseudomonas fluorescens and other biocontrol organisms mediate defence against the anthracnose pathogen in mango

Talc-based bioformulations containing cells of Pseudomonas fluorescens, Bacillus subtilis and Saccharomyces cerevisiae were evaluated for their potential to attack the mango (Mangifera indica L.) anthracnose pathogen Colletotrichum gloeosporioides Penz. under endemic conditions. The preharvest aerial spray was given at fortnightly and monthly intervals. The plant growth-promoting rhizobacteria Pseudomonas fluorescens (FP7) amended with chitin sprayed at fortnightly intervals gave the maximum induction of flowering, a yield attribute in the preharvest stage, consequently reduced latent symptoms were recorded at the postharvest stage. An enormous induction of the defence-mediating lytic enzymes chitinase and β-1,3-glucanase was recorded in colorimetric assay and the expression of discrete bands in native PAGE analysis after FP7 + chitin treatment. The enhanced expression of defence-mediating enzymes may collectively contribute to suppress the anthracnose pathogen, leading to improved yield attributes.

Chitin stimulates development and sporulation of arbuscular mycorrhizal fungi

Chitin added to sand-soil based cultivation substrates stimulated the root colonization, growth of extraradical mycelium and production of spores of arbuscular mycorrhizal fungi (AMF) in three experiments with Allium amppelloprasum, Plantago lanceolata and Lactuca sativa as host plants. Stimulation of AMF sporulation was also observed when autoclaved mycelium of Fusarium oxysporum was used instead of chitin. Increased numbers of actinomycetes in the substrate as a result of chitin treatment were recorded.