Prof. Appa Rao Podile - Academia.edu (original) (raw)

Papers by Prof. Appa Rao Podile

Natural immunity present in all the plants against most of the pathogens is called as non-host re... more Natural immunity present in all the plants against most of the pathogens is called as non-host resistance (NHR). Although NHR is most durable form of resistance, it was less studied compared to other forms of resistance. We compared transcriptional changes in tomato during non-host ('Magnaporthe grisea') and compatible ('Alternaria alternata' f. sp. 'lycopersici') interactions using Agilent microarray GeneChip containing 44,000 probe sets. The experiment was designed to understand the early and late responses of tomato leaves inoculated with non-host and compatible pathogens. Microarray data revealed that the expression profiles in the non- host and compatible interactions at 6 h post inoculation (hpi) and 24 hpi largely overlapped indicating that a set of genes are activated during plant-pathogen interaction. However, these genes were expressed much earlier in NHR compared to a compatible interaction. NHR is, therefore, an accelerated and amplified basal def...

Journal of Plant Physiology

Plant growth promoting rhizobacteria (PGPR) are extensively used as biofertilizers to improve the... more Plant growth promoting rhizobacteria (PGPR) are extensively used as biofertilizers to improve the soil nutrition for a variety of crop plants. The plant-PGPR interaction, with special reference to chemical signalling molecules is not understood clearly, unlike other beneficial plant-microbe interactions. Chemo-attraction of a PGPR from soil microbial pool towards a plant could be dependent on some of the molecules in the plant root exudates (REs), similar to the beneficial association of legume-rhizobia. In this study, a few functional properties of PGPR like growth, chemotaxis, and biofilm formation by two PGPR strains viz., Bacillus sonorensis RS4 and Pseudomonas aeruginosa RP2 were assessed in the presence of groundnut REs. Functional properties of both the strains were significantly influenced by the REs in a strain-dependent manner. Metabolite profiling of the REs from PGPR-bacterized (RS4 or RP2) and non-bacterized seedlings was performed with GC-MS/MS after 12 and 24 days of growth. A total of 75 metabolites were detected in groundnut REs. Threonine and glyoxylic oxime acid were detected in RP2-bacterized REs, while serine, pentanoic acid, glucopyranoside, tartaric acid, and 2-pyrrolidinone were detected in REs of seedlings bacterized with RP2 and RS4. The results suggested that the PGPR induced distinct variations in the REs. Identification of the interaction-specific metabolites will be useful to develop effective PGPR based bio-formulations for better PGPR colonization and improving crop yields.

Enzyme and Microbial Technology

International Journal of Biological Macromolecules

Transactions of the Indian National Academy of Engineering

The ongoing global crisis due to Coronavirus disease-2019 (COVID-19) pandemic has caused an enorm... more The ongoing global crisis due to Coronavirus disease-2019 (COVID-19) pandemic has caused an enormous socioeconomic burden. A novel coronavirus causing severe acute respiratory syndrome (SARS-CoV-2) that evolved from a virus infecting bats is responsible for COVID-19, first reported in the Chinese city of Wuhan. In the absence of any specific scientifically proven and clinically tested drug or vaccine against SARS-CoV-2, the virus is wreaking havoc across the world, claiming more than 2,50,000 lives in less than 5 months, and posed a global health emergency. The scientific community is relentlessly working on the design and testing of vaccines and antiviral drugs against the novel coronavirus, several of which have reached advanced stages of testing and are undergoing clinical trials. Here we discuss the recent advances and developments in understanding the etiology and epidemiology of the COVID-19 pandemic, the factors influencing the disease transmission, and the countermeasures adopted to combat and stop further spread of the disease.

International Journal of Biological Macromolecules

International Journal of Biological Macromolecules

Scientific Reports

Humans have exploited natural resources for a variety of applications. Chitin and its derivative ... more Humans have exploited natural resources for a variety of applications. Chitin and its derivative chitin oligosaccharides (CHOS) have potential biomedical and agricultural applications. Availability of CHOS with the desired length has been a major limitation in the optimum use of such natural resources. Here, we report a single domain hyper-transglycosylating chitinase, which generates longer CHOS, from Enterobacter cloacae subsp. cloacae 13047 (EcChi1). EcChi1 was optimally active at pH 5.0 and 40 °C with a K m of 15.2 mg ml −1 , and k cat /K m of 0.011× 10 2 mg −1 ml min −1 on colloidal chitin. The profile of the hydrolytic products, major product being chitobiose, released from CHOS indicated that EcChi1 was an endo-acting enzyme. Transglycosylation (TG) by EcChi1 on trimeric to hexameric CHOS resulted in the formation of longer CHOS for a prolonged duration. EcChi1 showed both chitobiase and TG activities, in addition to hydrolytic activity. The TG by EcChi1 was dependent, to some extent, on the length of the CHOS substrate and concentration of the enzyme. Homology modeling and docking with CHOS suggested that EcChi1 has a deep substrate-binding groove lined with aromatic amino acids, which is a characteristic feature of a processive enzyme. Chitin [(C 8 H 13 O 5 N) n»1 ], is a linear homopolymer of N-acetyl glucosamine (GlcNAc) units linked through β (1 → 4) glycosidic bonds. It is an abundant renewable natural resource next to cellulose in the biosphere. Chitin is a primary structural component of the fungal cell wall, insects, molluscs, squid, internal shells of cephalopods and the exoskeletons of arthropod, exists in three biological forms i.e. α-chitin, β-chitin and γ-chitin. The presence of acetamide group (NH-CO-CH 3) allows increased hydrogen bonding between adjacent polymers, giving increased strength of chitin-polymer matrix. Chitin oligosaccharides (CHOS) generated from polymeric chitin with specific composition and length have potential applications. The remarkable properties of CHOS i.e. bio-degradability, bio-compatibility, and non-toxicity suit wider industrial application 1, 2. Production of CHOS by chemical methods has been challenging due to disadvantages like non-specific random hydrolysis, and difficulty to remove the acidity of the CHOS oligomers 3. Chitinases could be possible alternatives for production of long chain CHOS, especially for biological applications. Chitinases (EC 3.2.1.14) hydrolyze chitin to chitin monomer (DP1; Degree of polymerization 1), chitin dimer (DP2) and CHOS of shorter length. Chitinases, classified into two glycoside hydrolase (GH) families i.e. GH18 and GH19 could be exochitinases that act terminally and endochitinases that cleave randomly at internal sites of the chitin, eventually producing a variety of low molecular mass or short length CHOS 4. Chitinases that act on crystalline polysaccharides need to associate and disrupt the polymer from packing and also direct the travelling of single polymer chain into the catalytic center through a catalytic groove, a mechanism called processivity 5, 6. The aromatic amino acids lining the substrate-binding site, facilitate processivity by functioning as a flexible and hydrophobic sheet and allow the polymer chain to slide 7, 8. A few of the GH18 chitinases exhibit an uncommon transglycosylation (TG), in addition to chitin hydrolysis, by introducing new glycosidic bonds between donor and acceptor saccharides 9. The GH18 chitinases gained special interest due to potential applications for the enzymatic production of CHOS by TG from chitin 10. Bacterial

Scientific reports, Jan 23, 2015

Serratia proteamaculans chitinase-D (SpChiD) has a unique combination of hydrolytic and transglyc... more Serratia proteamaculans chitinase-D (SpChiD) has a unique combination of hydrolytic and transglycosylation (TG) activities. The TG activity of SpChiD can be used for large-scale production of chito-oligosaccharides (CHOS). The multiple activities (hydrolytic and/or chitobiase activities and TG) of SpChiD appear to be strongly influenced by the substrate-binding cleft. Here, we report the unique property of SpChiD substrate-binding cleft, wherein, the residues Tyr28, Val35 and Thr36 control chitobiase activity and the residues Trp160 and Trp290 are crucial for TG activity. Mutants with reduced (V35G and T36G/F) or no (SpChiDΔ30-42 and Y28A) chitobiase activity produced higher amounts of the quantifiable even-chain TG product with degree of polymerization (DP)-6, indicating that the chitobiase and TG activities are inversely related. In addition to its unprecedented catalytic properties, unlike other chitinases, the single modular SpChiD showed dual unfolding transitions. Ligand-induc...

ABSTRACT Harpins are heat-stable, glycine-rich proteins secreted by several Gram-negative phytopa... more ABSTRACT Harpins are heat-stable, glycine-rich proteins secreted by several Gram-negative phytopathogenic bacteria, involved in the induction of hypersensitive response in non-host plants. HrpZPss is highly heat stable, exists as a polydispersed, multimeric protein in nature and the functional significance for its existence in many oligomeric forms, remains still unclear. It was suggested that the leucine zipper-like motifs (LZMs) may take part in the formation of oligomeric aggregates, which may be responsible for HR elicitation by harpins and for their high thermal stability. To test the involvement of LZMs in HR elicitation and induction of defense responses, we have generated deletion mutants with or without LZMs and analysed their ability to induce HR, and/or activate the defense responses. The deletion mutant HrpZMM1, with no LZM also elicited HR as well as defense responses in tobacco suggesting the LZMs are not essential for elicitor activity of HrpZPss. However, the ability to elicit defense responses may be linked with the ability to induce HR.

Proceedings of the Indian National Science Academy, 2014

Plant growth promoting rhizobacteria (PGPR) exhibit an intricate and interdependent relationship ... more Plant growth promoting rhizobacteria (PGPR) exhibit an intricate and interdependent relationship with plants, which involves biotic and abiotic factors of the rhizosphere region other than the two partners. Success of PGPR is dependent on their survival and establishment on the root/rhizosphere. In this article, we have highlighted root colonization and celldensity dependant quorum sensing as the two important factors that play a key role in determining the outcome of the interaction.

Phytopathology, 2005

Late leaf spot (LLS), caused by Phaeoisariopsis personata, is a foliar disease of groundnut or pe... more Late leaf spot (LLS), caused by Phaeoisariopsis personata, is a foliar disease of groundnut or peanut (Arachis hypogaea) with high economic and global importance. Antifungal and chitinolytic Bacillus circulans GRS 243 and Serratia marcescens GPS 5, selected among a collection of 393 peanut-associated bacteria, were applied as a prophylactic foliar spray and tested for control of LLS. Chitin-supplemented application of B. circulans GRS 243 and S. marcescens GPS 5 resulted in improved biological control of LLS disease. Supplementation of bacterial cells with 1% (wt/vol) colloidal chitin reduced lesion frequency by 60% compared with application of bacterial cells alone, in the greenhouse. Chitinsupplemented application of GRS 243 and GPS 5 also resulted in improved and stable control of LLS in a repeated field experiment and increased the pod yields by 62 and 75%, respectively, compared with the control. Chitin-supplemented application of GPS 5 was tested in six onfarm trials, and the ...

Canadian Journal of Microbiology, 2005

Bacteria associated with 6 habitats of groundnut were evaluated for their broad-spectrum antifung... more Bacteria associated with 6 habitats of groundnut were evaluated for their broad-spectrum antifungal activity and suppression of collar rot (Aspergillus niger) of groundnut. Three hundred and ninety-three strains were tested against 8 fungal pathogens of groundnut including 5 necrotrophic fungi, Aspergillus flavus, A. niger, Rhizoctonia bataticola, Rhizoctonia solani, and Sclerotium rolfsii, and 3 biotrophic fungi, Cercospora arachidicola, Phaeoisariopsis personata, and Puccinia arachidis. Pseudomonas sp. GRS 175, Pseudomonas aeruginosa GPS 21, GSE 18, GSE 19, and GSE 30, and their cell-free culture filtrates were highly antagonistic to all the test fungi. The cell-free culture filtrates of these bacteria were fungicidal and induced mycelial deformations including hyphal bulging and vacuolization in necrotrophic fungi. The cell-free culture filtrates at 10% (v/v) concentration significantly inhibited the spore germination of biotrophic fungi. In the greenhouse, P. aeruginosa GSE 18 e...

Journal of Phytopathology, 1998

... i .r:i^, I Fig. 2 Photomicrographs of h>phue of Fusurium uchim cuiuire grown m... more ... i .r:i^, I Fig. 2 Photomicrographs of h>phue of Fusurium uchim cuiuire grown m Richard's mt'diuiB iRM) or m presence of 40".) (\ ceil free culture fillrale oiBaciHu.^ yuhiilh A¥ 1 in RM and mounted in cc-tlon blue. A \'egeluti\e hvphae with coiiidia < x UKM t'rt>m KM. ...

Agrochemicals Detection, Treatment and Remediation

Carbohydrate Polymer Technologies and Applications

Journal of Agricultural and Food Chemistry

International Journal of Biological Macromolecules

Natural immunity present in all the plants against most of the pathogens is called as non-host re... more Natural immunity present in all the plants against most of the pathogens is called as non-host resistance (NHR). Although NHR is most durable form of resistance, it was less studied compared to other forms of resistance. We compared transcriptional changes in tomato during non-host ('Magnaporthe grisea') and compatible ('Alternaria alternata' f. sp. 'lycopersici') interactions using Agilent microarray GeneChip containing 44,000 probe sets. The experiment was designed to understand the early and late responses of tomato leaves inoculated with non-host and compatible pathogens. Microarray data revealed that the expression profiles in the non- host and compatible interactions at 6 h post inoculation (hpi) and 24 hpi largely overlapped indicating that a set of genes are activated during plant-pathogen interaction. However, these genes were expressed much earlier in NHR compared to a compatible interaction. NHR is, therefore, an accelerated and amplified basal def...

Journal of Plant Physiology

Plant growth promoting rhizobacteria (PGPR) are extensively used as biofertilizers to improve the... more Plant growth promoting rhizobacteria (PGPR) are extensively used as biofertilizers to improve the soil nutrition for a variety of crop plants. The plant-PGPR interaction, with special reference to chemical signalling molecules is not understood clearly, unlike other beneficial plant-microbe interactions. Chemo-attraction of a PGPR from soil microbial pool towards a plant could be dependent on some of the molecules in the plant root exudates (REs), similar to the beneficial association of legume-rhizobia. In this study, a few functional properties of PGPR like growth, chemotaxis, and biofilm formation by two PGPR strains viz., Bacillus sonorensis RS4 and Pseudomonas aeruginosa RP2 were assessed in the presence of groundnut REs. Functional properties of both the strains were significantly influenced by the REs in a strain-dependent manner. Metabolite profiling of the REs from PGPR-bacterized (RS4 or RP2) and non-bacterized seedlings was performed with GC-MS/MS after 12 and 24 days of growth. A total of 75 metabolites were detected in groundnut REs. Threonine and glyoxylic oxime acid were detected in RP2-bacterized REs, while serine, pentanoic acid, glucopyranoside, tartaric acid, and 2-pyrrolidinone were detected in REs of seedlings bacterized with RP2 and RS4. The results suggested that the PGPR induced distinct variations in the REs. Identification of the interaction-specific metabolites will be useful to develop effective PGPR based bio-formulations for better PGPR colonization and improving crop yields.

Enzyme and Microbial Technology

International Journal of Biological Macromolecules

Transactions of the Indian National Academy of Engineering

The ongoing global crisis due to Coronavirus disease-2019 (COVID-19) pandemic has caused an enorm... more The ongoing global crisis due to Coronavirus disease-2019 (COVID-19) pandemic has caused an enormous socioeconomic burden. A novel coronavirus causing severe acute respiratory syndrome (SARS-CoV-2) that evolved from a virus infecting bats is responsible for COVID-19, first reported in the Chinese city of Wuhan. In the absence of any specific scientifically proven and clinically tested drug or vaccine against SARS-CoV-2, the virus is wreaking havoc across the world, claiming more than 2,50,000 lives in less than 5 months, and posed a global health emergency. The scientific community is relentlessly working on the design and testing of vaccines and antiviral drugs against the novel coronavirus, several of which have reached advanced stages of testing and are undergoing clinical trials. Here we discuss the recent advances and developments in understanding the etiology and epidemiology of the COVID-19 pandemic, the factors influencing the disease transmission, and the countermeasures adopted to combat and stop further spread of the disease.

International Journal of Biological Macromolecules

International Journal of Biological Macromolecules

Scientific Reports

Humans have exploited natural resources for a variety of applications. Chitin and its derivative ... more Humans have exploited natural resources for a variety of applications. Chitin and its derivative chitin oligosaccharides (CHOS) have potential biomedical and agricultural applications. Availability of CHOS with the desired length has been a major limitation in the optimum use of such natural resources. Here, we report a single domain hyper-transglycosylating chitinase, which generates longer CHOS, from Enterobacter cloacae subsp. cloacae 13047 (EcChi1). EcChi1 was optimally active at pH 5.0 and 40 °C with a K m of 15.2 mg ml −1 , and k cat /K m of 0.011× 10 2 mg −1 ml min −1 on colloidal chitin. The profile of the hydrolytic products, major product being chitobiose, released from CHOS indicated that EcChi1 was an endo-acting enzyme. Transglycosylation (TG) by EcChi1 on trimeric to hexameric CHOS resulted in the formation of longer CHOS for a prolonged duration. EcChi1 showed both chitobiase and TG activities, in addition to hydrolytic activity. The TG by EcChi1 was dependent, to some extent, on the length of the CHOS substrate and concentration of the enzyme. Homology modeling and docking with CHOS suggested that EcChi1 has a deep substrate-binding groove lined with aromatic amino acids, which is a characteristic feature of a processive enzyme. Chitin [(C 8 H 13 O 5 N) n»1 ], is a linear homopolymer of N-acetyl glucosamine (GlcNAc) units linked through β (1 → 4) glycosidic bonds. It is an abundant renewable natural resource next to cellulose in the biosphere. Chitin is a primary structural component of the fungal cell wall, insects, molluscs, squid, internal shells of cephalopods and the exoskeletons of arthropod, exists in three biological forms i.e. α-chitin, β-chitin and γ-chitin. The presence of acetamide group (NH-CO-CH 3) allows increased hydrogen bonding between adjacent polymers, giving increased strength of chitin-polymer matrix. Chitin oligosaccharides (CHOS) generated from polymeric chitin with specific composition and length have potential applications. The remarkable properties of CHOS i.e. bio-degradability, bio-compatibility, and non-toxicity suit wider industrial application 1, 2. Production of CHOS by chemical methods has been challenging due to disadvantages like non-specific random hydrolysis, and difficulty to remove the acidity of the CHOS oligomers 3. Chitinases could be possible alternatives for production of long chain CHOS, especially for biological applications. Chitinases (EC 3.2.1.14) hydrolyze chitin to chitin monomer (DP1; Degree of polymerization 1), chitin dimer (DP2) and CHOS of shorter length. Chitinases, classified into two glycoside hydrolase (GH) families i.e. GH18 and GH19 could be exochitinases that act terminally and endochitinases that cleave randomly at internal sites of the chitin, eventually producing a variety of low molecular mass or short length CHOS 4. Chitinases that act on crystalline polysaccharides need to associate and disrupt the polymer from packing and also direct the travelling of single polymer chain into the catalytic center through a catalytic groove, a mechanism called processivity 5, 6. The aromatic amino acids lining the substrate-binding site, facilitate processivity by functioning as a flexible and hydrophobic sheet and allow the polymer chain to slide 7, 8. A few of the GH18 chitinases exhibit an uncommon transglycosylation (TG), in addition to chitin hydrolysis, by introducing new glycosidic bonds between donor and acceptor saccharides 9. The GH18 chitinases gained special interest due to potential applications for the enzymatic production of CHOS by TG from chitin 10. Bacterial

Scientific reports, Jan 23, 2015

Serratia proteamaculans chitinase-D (SpChiD) has a unique combination of hydrolytic and transglyc... more Serratia proteamaculans chitinase-D (SpChiD) has a unique combination of hydrolytic and transglycosylation (TG) activities. The TG activity of SpChiD can be used for large-scale production of chito-oligosaccharides (CHOS). The multiple activities (hydrolytic and/or chitobiase activities and TG) of SpChiD appear to be strongly influenced by the substrate-binding cleft. Here, we report the unique property of SpChiD substrate-binding cleft, wherein, the residues Tyr28, Val35 and Thr36 control chitobiase activity and the residues Trp160 and Trp290 are crucial for TG activity. Mutants with reduced (V35G and T36G/F) or no (SpChiDΔ30-42 and Y28A) chitobiase activity produced higher amounts of the quantifiable even-chain TG product with degree of polymerization (DP)-6, indicating that the chitobiase and TG activities are inversely related. In addition to its unprecedented catalytic properties, unlike other chitinases, the single modular SpChiD showed dual unfolding transitions. Ligand-induc...

ABSTRACT Harpins are heat-stable, glycine-rich proteins secreted by several Gram-negative phytopa... more ABSTRACT Harpins are heat-stable, glycine-rich proteins secreted by several Gram-negative phytopathogenic bacteria, involved in the induction of hypersensitive response in non-host plants. HrpZPss is highly heat stable, exists as a polydispersed, multimeric protein in nature and the functional significance for its existence in many oligomeric forms, remains still unclear. It was suggested that the leucine zipper-like motifs (LZMs) may take part in the formation of oligomeric aggregates, which may be responsible for HR elicitation by harpins and for their high thermal stability. To test the involvement of LZMs in HR elicitation and induction of defense responses, we have generated deletion mutants with or without LZMs and analysed their ability to induce HR, and/or activate the defense responses. The deletion mutant HrpZMM1, with no LZM also elicited HR as well as defense responses in tobacco suggesting the LZMs are not essential for elicitor activity of HrpZPss. However, the ability to elicit defense responses may be linked with the ability to induce HR.

Proceedings of the Indian National Science Academy, 2014

Plant growth promoting rhizobacteria (PGPR) exhibit an intricate and interdependent relationship ... more Plant growth promoting rhizobacteria (PGPR) exhibit an intricate and interdependent relationship with plants, which involves biotic and abiotic factors of the rhizosphere region other than the two partners. Success of PGPR is dependent on their survival and establishment on the root/rhizosphere. In this article, we have highlighted root colonization and celldensity dependant quorum sensing as the two important factors that play a key role in determining the outcome of the interaction.

Phytopathology, 2005

Late leaf spot (LLS), caused by Phaeoisariopsis personata, is a foliar disease of groundnut or pe... more Late leaf spot (LLS), caused by Phaeoisariopsis personata, is a foliar disease of groundnut or peanut (Arachis hypogaea) with high economic and global importance. Antifungal and chitinolytic Bacillus circulans GRS 243 and Serratia marcescens GPS 5, selected among a collection of 393 peanut-associated bacteria, were applied as a prophylactic foliar spray and tested for control of LLS. Chitin-supplemented application of B. circulans GRS 243 and S. marcescens GPS 5 resulted in improved biological control of LLS disease. Supplementation of bacterial cells with 1% (wt/vol) colloidal chitin reduced lesion frequency by 60% compared with application of bacterial cells alone, in the greenhouse. Chitinsupplemented application of GRS 243 and GPS 5 also resulted in improved and stable control of LLS in a repeated field experiment and increased the pod yields by 62 and 75%, respectively, compared with the control. Chitin-supplemented application of GPS 5 was tested in six onfarm trials, and the ...

Canadian Journal of Microbiology, 2005

Bacteria associated with 6 habitats of groundnut were evaluated for their broad-spectrum antifung... more Bacteria associated with 6 habitats of groundnut were evaluated for their broad-spectrum antifungal activity and suppression of collar rot (Aspergillus niger) of groundnut. Three hundred and ninety-three strains were tested against 8 fungal pathogens of groundnut including 5 necrotrophic fungi, Aspergillus flavus, A. niger, Rhizoctonia bataticola, Rhizoctonia solani, and Sclerotium rolfsii, and 3 biotrophic fungi, Cercospora arachidicola, Phaeoisariopsis personata, and Puccinia arachidis. Pseudomonas sp. GRS 175, Pseudomonas aeruginosa GPS 21, GSE 18, GSE 19, and GSE 30, and their cell-free culture filtrates were highly antagonistic to all the test fungi. The cell-free culture filtrates of these bacteria were fungicidal and induced mycelial deformations including hyphal bulging and vacuolization in necrotrophic fungi. The cell-free culture filtrates at 10% (v/v) concentration significantly inhibited the spore germination of biotrophic fungi. In the greenhouse, P. aeruginosa GSE 18 e...

Journal of Phytopathology, 1998

... i .r:i^, I Fig. 2 Photomicrographs of h>phue of Fusurium uchim cuiuire grown m... more ... i .r:i^, I Fig. 2 Photomicrographs of h>phue of Fusurium uchim cuiuire grown m Richard's mt'diuiB iRM) or m presence of 40".) (\ ceil free culture fillrale oiBaciHu.^ yuhiilh A¥ 1 in RM and mounted in cc-tlon blue. A \'egeluti\e hvphae with coiiidia < x UKM t'rt>m KM. ...

Agrochemicals Detection, Treatment and Remediation

Carbohydrate Polymer Technologies and Applications

Journal of Agricultural and Food Chemistry

International Journal of Biological Macromolecules