More than 200 insect pests are found growing on pigeonpea. Insects lay eggs, attack and feed on l... more More than 200 insect pests are found growing on pigeonpea. Insects lay eggs, attack and feed on leaves, flowers and developing pods. Plants have developed elaborate defenses against these insect pests. The present work evaluates protease inhibitor (PI) based defense of pigeonpea in leaves and flowers. PIs in the extracts of these tender tissues were detected by using gel X-ray film contact print method. Up to three PIs (PI-3, PI-4 and PI-5) were detected in these tissues as against nine (PI-1-PI-9) in mature seeds. PI-3 is the major component of these tissues. Mechanical wounding, insect chewing, fungal pathogenesis and application of salicylic acid induced PIs in pigeonpea in these tissues. Induction was found to be local as well as systemic but local response was stronger than systemic response. During both local and systemic induction, PI-3 appeared first. In spite of the presence and induction of PIs in these tender tissues and seeds farmers continue to suffer yield loses. This is due to the weak expression of PIs. However the ability of the plant to respond to external stimuli by producing defense proteins does not seem to be compromised. This study therefore indicates that PIs are components of both constitutive and inducible defense and provide a ground for designing stronger inducible defense (PIs or other insect toxin based) in pigeonpea.
This paper evaluates α-amylase inhibitor (α-AI) mediated defense of pigeonpea against Helicoverpa... more This paper evaluates α-amylase inhibitor (α-AI) mediated defense of pigeonpea against Helicoverpa armigera. A bifunctional α-amylase/trypsin inhibitor was purified from the seeds of pigeonpea by native liquid phase isoelectric focusing (N-LP-IEF), affinity chromatography and preparative electrophoresis. Its in-vivo and in-vitro interaction with midgut amylases of H. armigera was studied along with growth inhibitory activity. One and two dimensional (2D) zymographic analyses revealed that the purified inhibitor is dimeric glycoprotein (60.2kDa and 56kDa) exist in a multi-isomeric form with five pI variants (pI 5.5 to 6.3). It was found to be heat labile with complete inactivation up to 80°C and stable over a wide range of pH (4-11). The slow binding and competitive type of α-amylase inhibition was observed with 0.08μM of dissociation constant (Ki) for the enzyme-inhibitor complex (EI). The internal protein sequence of two subunits obtained by mass spectrometry matched with cereal-type α-AI, a conserved domain from AAI_LTSS superfamily and sialyltransferase-like protein respectively. In-vivo studies indicated up-regulation of total midgut α-amylase activity with negative effect on growth rate of H. armigera suggesting its suitability for pest control.
ABSTRACT Seeds of pigeonpea are known to accumulate protease inhibitors (PIs), belonging to the B... more ABSTRACT Seeds of pigeonpea are known to accumulate protease inhibitors (PIs), belonging to the Bowman-Burk inhibitor family. PIs are important for natural defense against phytophagous insect pests. Most insects attack crops at the early stages of seed development. Accumulation patterns of individual PIs and their relationship with each other were studied in developing seeds of 76 pigeonpea lines derived from BDN2 cultivar by ethyl methane sulfonate induced chemical mutagenesis. PIs extracted from these lines, collected between 10 and 40 days after flowering (DAF) and from mature seeds of BDN2 cultivar, were detected by using gel X-ray film contact print method. A total of 9 trypsin–chymotrypsin inhibitors were detected in mature seeds. All the nine PIs were capable of inhibiting proteases. Appearance of detectable levels of individual PIs started around 10 DAF. The PI-3 appeared early and was the most stable. It was accumulated in all the studied lines and was also detected in 84 % of the samples collected 10 DAF. In particular, 14 DAF, the individual PIs were accumulated and accumulation sequence was observed (PI-3, PI-2, PI-5, PI-7, PI-6, PI-4, PI-8, PI-9 and PI-1). Accumulation continued up to 40 DAF when seeds started hardening. Chemical mutagenesis could not produce any variation in the profile of individual PIs in the 76 studied lines in mature seeds. The process of accumulation of inhibitors is sturdy and mutagenesis fails to alter it. The robust mechanism is responsible for early appearance of PI-3. Early accumulated PIs in this study need further exploration for strengthening natural defense of pigeonpea against pests.
Here, we report multiple molecular forms of Albizia lebbeck trypsin inhibitors (AlTIs) by using a... more Here, we report multiple molecular forms of Albizia lebbeck trypsin inhibitors (AlTIs) by using a simple and sensitive gel X-ray film contact print technique. About 17 AlTIs were detected in the seed extracts of A. lebbeck. Two groups of AlTIs—1 major (10 AlTIs; slow migration on the gel) and 1 minor (7 AlTIs; fast migration on the gel) were identified. The former was specific only toward trypsin. However, the latter was specific toward both trypsin and Helicoverpa armigera gut proteinases (HaGPs). The most potent AlTI (AlTI13) was purified to assess its in vivo bioefficacy toward HaGPs. Purification was achieved using (NH4)2SO4 fractionation, Sephadex G-100 column chromatography, and preparative native-polyacrylamide gel electrophoresis (PAGE). The dose dependent bioefficacies of AlTIs in the (NH4)2SO4 F3 fractions (0.1%, 0.5%, and 1%) were approximately 79%, 83%, and 90%, respectively, resulting in reductions in the average larval weight of H. armigera. Artificial diet containing a single dose of AlTI13 (5 μg/g diet) reduced the larval weight by about 76%, with 60% mortality. The half-maximal inhibitory concentrations (IC50) of AlTI13 for trypsin and HaGPs were 0.14 and 0.17 μmol/ml, respectively. The optimum conditions for AlTI13 were pH 8 and temperatures ranging from 35 to 40 °C. Reducing sodium dodecyl sulfate-PAGE analysis indicated that ~ 28 kDa Kunitz-like trypsin inhibitor was present. Thus, we showed that AlTIs, particularly, AlTI13 of A. lebbeck could be used as a transgene macromolecule to markedly increase insect resistance in genetically engineered plants.
Most of the plant protection strategies are focused on selection and application of the natural p... more Most of the plant protection strategies are focused on selection and application of the natural proteinase inhibitors (PIs) against insect pests. In addition, PIs also play a vital role in medicine for treatment of immunity related diseases. PI activity exists mainly in seeds, leaves and flowers of plants. In search of novel PIs, 135 different plant tissue extracts (leaf, flower and seed) were screened for their PI (trypsin, chymotrypsin and Helicoverpa gut proteinase inhibitors) activities by using dot-blot assays. Most of the plant tissues screened revealed moderate PI activity, few showed low PI activity and very few of them showed strong PI activity against trypsin, chymotrypsin and Helicoverpa gut proteinases. The inhibitory potency of positive samples was further determined by solution assays. Five plants namely Arachis hypogaea, Vigna sinensis, Dolichos lablab, Phaseolus aureus and Cassia siamea showed higher activity which ranged from 22.91 to 58.33 %. Higher activities recorded in the seed as compare to leaf and flower tissues. Dolichos lablab showed highest PI activity (58.33 %) followed by Cassia siamea (52.08 %). PI activity was found to be distributed unequally in ammonium sulfate (NH2SO4) fractions.
Abstract: Vermiwash was found to contain enzyme cocktail of proteases, amylases, urease and phosp... more Abstract: Vermiwash was found to contain enzyme cocktail of proteases, amylases, urease and phosphatase. Microbiological study of vermiwash revealed that it contains nitrogen-fixing bacteria like Azotobactrer sp., Agrobacterium sp. and Rhizobium sp. and some ...
Most of the plant protection strategies are focused on selection and application of the natural p... more Most of the plant protection strategies are focused on selection and application of the natural proteinase inhibitors (PIs) against insect pests. In addition, PIs also play a vital role in medicine for treatment of immunity related diseases. PI activity exists mainly in seeds, leaves and flowers of plants. In search of novel PIs, 135 different plant tissue extracts (leaf, flower and seed) were screened for their PI (trypsin, chymotrypsin and Helicoverpa gut proteinase inhibitors) activities by using dot-blot assays. Most of the plant tissues screened revealed moderate PI activity, few showed low PI activity and very few of them showed strong PI activity against trypsin, chymotrypsin and Helicoverpa gut proteinases. The inhibitory potency of positive samples was further determined by solution assays. Five plants namely Arachis hypogaea, Vigna sinensis, Dolichos lablab, Phaseolus aureus and Cassia siamea showed higher activity which ranged from 22.91 to 58.33 %. Higher activities reco...
More than 200 insect pests are found growing on pigeonpea. Insects lay eggs, attack and feed on l... more More than 200 insect pests are found growing on pigeonpea. Insects lay eggs, attack and feed on leaves, flowers and developing pods. Plants have developed elaborate defenses against these insect pests. The present work evaluates protease inhibitor (PI) based defense of pigeonpea in leaves and flowers. PIs in the extracts of these tender tissues were detected by using gel X-ray film contact print method. Up to three PIs (PI-3, PI-4 and PI-5) were detected in these tissues as against nine (PI-1-PI-9) in mature seeds. PI-3 is the major component of these tissues. Mechanical wounding, insect chewing, fungal pathogenesis and application of salicylic acid induced PIs in pigeonpea in these tissues. Induction was found to be local as well as systemic but local response was stronger than systemic response. During both local and systemic induction, PI-3 appeared first. In spite of the presence and induction of PIs in these tender tissues and seeds farmers continue to suffer yield loses. This is due to the weak expression of PIs. However the ability of the plant to respond to external stimuli by producing defense proteins does not seem to be compromised. This study therefore indicates that PIs are components of both constitutive and inducible defense and provide a ground for designing stronger inducible defense (PIs or other insect toxin based) in pigeonpea.
This paper evaluates α-amylase inhibitor (α-AI) mediated defense of pigeonpea against Helicoverpa... more This paper evaluates α-amylase inhibitor (α-AI) mediated defense of pigeonpea against Helicoverpa armigera. A bifunctional α-amylase/trypsin inhibitor was purified from the seeds of pigeonpea by native liquid phase isoelectric focusing (N-LP-IEF), affinity chromatography and preparative electrophoresis. Its in-vivo and in-vitro interaction with midgut amylases of H. armigera was studied along with growth inhibitory activity. One and two dimensional (2D) zymographic analyses revealed that the purified inhibitor is dimeric glycoprotein (60.2kDa and 56kDa) exist in a multi-isomeric form with five pI variants (pI 5.5 to 6.3). It was found to be heat labile with complete inactivation up to 80°C and stable over a wide range of pH (4-11). The slow binding and competitive type of α-amylase inhibition was observed with 0.08μM of dissociation constant (Ki) for the enzyme-inhibitor complex (EI). The internal protein sequence of two subunits obtained by mass spectrometry matched with cereal-type α-AI, a conserved domain from AAI_LTSS superfamily and sialyltransferase-like protein respectively. In-vivo studies indicated up-regulation of total midgut α-amylase activity with negative effect on growth rate of H. armigera suggesting its suitability for pest control.
ABSTRACT Seeds of pigeonpea are known to accumulate protease inhibitors (PIs), belonging to the B... more ABSTRACT Seeds of pigeonpea are known to accumulate protease inhibitors (PIs), belonging to the Bowman-Burk inhibitor family. PIs are important for natural defense against phytophagous insect pests. Most insects attack crops at the early stages of seed development. Accumulation patterns of individual PIs and their relationship with each other were studied in developing seeds of 76 pigeonpea lines derived from BDN2 cultivar by ethyl methane sulfonate induced chemical mutagenesis. PIs extracted from these lines, collected between 10 and 40 days after flowering (DAF) and from mature seeds of BDN2 cultivar, were detected by using gel X-ray film contact print method. A total of 9 trypsin–chymotrypsin inhibitors were detected in mature seeds. All the nine PIs were capable of inhibiting proteases. Appearance of detectable levels of individual PIs started around 10 DAF. The PI-3 appeared early and was the most stable. It was accumulated in all the studied lines and was also detected in 84 % of the samples collected 10 DAF. In particular, 14 DAF, the individual PIs were accumulated and accumulation sequence was observed (PI-3, PI-2, PI-5, PI-7, PI-6, PI-4, PI-8, PI-9 and PI-1). Accumulation continued up to 40 DAF when seeds started hardening. Chemical mutagenesis could not produce any variation in the profile of individual PIs in the 76 studied lines in mature seeds. The process of accumulation of inhibitors is sturdy and mutagenesis fails to alter it. The robust mechanism is responsible for early appearance of PI-3. Early accumulated PIs in this study need further exploration for strengthening natural defense of pigeonpea against pests.
Here, we report multiple molecular forms of Albizia lebbeck trypsin inhibitors (AlTIs) by using a... more Here, we report multiple molecular forms of Albizia lebbeck trypsin inhibitors (AlTIs) by using a simple and sensitive gel X-ray film contact print technique. About 17 AlTIs were detected in the seed extracts of A. lebbeck. Two groups of AlTIs—1 major (10 AlTIs; slow migration on the gel) and 1 minor (7 AlTIs; fast migration on the gel) were identified. The former was specific only toward trypsin. However, the latter was specific toward both trypsin and Helicoverpa armigera gut proteinases (HaGPs). The most potent AlTI (AlTI13) was purified to assess its in vivo bioefficacy toward HaGPs. Purification was achieved using (NH4)2SO4 fractionation, Sephadex G-100 column chromatography, and preparative native-polyacrylamide gel electrophoresis (PAGE). The dose dependent bioefficacies of AlTIs in the (NH4)2SO4 F3 fractions (0.1%, 0.5%, and 1%) were approximately 79%, 83%, and 90%, respectively, resulting in reductions in the average larval weight of H. armigera. Artificial diet containing a single dose of AlTI13 (5 μg/g diet) reduced the larval weight by about 76%, with 60% mortality. The half-maximal inhibitory concentrations (IC50) of AlTI13 for trypsin and HaGPs were 0.14 and 0.17 μmol/ml, respectively. The optimum conditions for AlTI13 were pH 8 and temperatures ranging from 35 to 40 °C. Reducing sodium dodecyl sulfate-PAGE analysis indicated that ~ 28 kDa Kunitz-like trypsin inhibitor was present. Thus, we showed that AlTIs, particularly, AlTI13 of A. lebbeck could be used as a transgene macromolecule to markedly increase insect resistance in genetically engineered plants.
Most of the plant protection strategies are focused on selection and application of the natural p... more Most of the plant protection strategies are focused on selection and application of the natural proteinase inhibitors (PIs) against insect pests. In addition, PIs also play a vital role in medicine for treatment of immunity related diseases. PI activity exists mainly in seeds, leaves and flowers of plants. In search of novel PIs, 135 different plant tissue extracts (leaf, flower and seed) were screened for their PI (trypsin, chymotrypsin and Helicoverpa gut proteinase inhibitors) activities by using dot-blot assays. Most of the plant tissues screened revealed moderate PI activity, few showed low PI activity and very few of them showed strong PI activity against trypsin, chymotrypsin and Helicoverpa gut proteinases. The inhibitory potency of positive samples was further determined by solution assays. Five plants namely Arachis hypogaea, Vigna sinensis, Dolichos lablab, Phaseolus aureus and Cassia siamea showed higher activity which ranged from 22.91 to 58.33 %. Higher activities recorded in the seed as compare to leaf and flower tissues. Dolichos lablab showed highest PI activity (58.33 %) followed by Cassia siamea (52.08 %). PI activity was found to be distributed unequally in ammonium sulfate (NH2SO4) fractions.
Abstract: Vermiwash was found to contain enzyme cocktail of proteases, amylases, urease and phosp... more Abstract: Vermiwash was found to contain enzyme cocktail of proteases, amylases, urease and phosphatase. Microbiological study of vermiwash revealed that it contains nitrogen-fixing bacteria like Azotobactrer sp., Agrobacterium sp. and Rhizobium sp. and some ...
Most of the plant protection strategies are focused on selection and application of the natural p... more Most of the plant protection strategies are focused on selection and application of the natural proteinase inhibitors (PIs) against insect pests. In addition, PIs also play a vital role in medicine for treatment of immunity related diseases. PI activity exists mainly in seeds, leaves and flowers of plants. In search of novel PIs, 135 different plant tissue extracts (leaf, flower and seed) were screened for their PI (trypsin, chymotrypsin and Helicoverpa gut proteinase inhibitors) activities by using dot-blot assays. Most of the plant tissues screened revealed moderate PI activity, few showed low PI activity and very few of them showed strong PI activity against trypsin, chymotrypsin and Helicoverpa gut proteinases. The inhibitory potency of positive samples was further determined by solution assays. Five plants namely Arachis hypogaea, Vigna sinensis, Dolichos lablab, Phaseolus aureus and Cassia siamea showed higher activity which ranged from 22.91 to 58.33 %. Higher activities reco...
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(PIs) against insect pests. In addition, PIs also play a vital role in medicine for treatment of immunity related
diseases. PI activity exists mainly in seeds, leaves and flowers of plants. In search of novel PIs, 135 different plant
tissue extracts (leaf, flower and seed) were screened for their PI (trypsin, chymotrypsin and Helicoverpa gut
proteinase inhibitors) activities by using dot-blot assays. Most of the plant tissues screened revealed moderate PI
activity, few showed low PI activity and very few of them showed strong PI activity against trypsin, chymotrypsin
and Helicoverpa gut proteinases. The inhibitory potency of positive samples was further determined by solution
assays. Five plants namely Arachis hypogaea, Vigna sinensis, Dolichos lablab, Phaseolus aureus and Cassia siamea
showed higher activity which ranged from 22.91 to 58.33 %. Higher activities recorded in the seed as compare to leaf
and flower tissues. Dolichos lablab showed highest PI activity (58.33 %) followed by Cassia siamea (52.08 %). PI
activity was found to be distributed unequally in ammonium sulfate (NH2SO4) fractions.
(PIs) against insect pests. In addition, PIs also play a vital role in medicine for treatment of immunity related
diseases. PI activity exists mainly in seeds, leaves and flowers of plants. In search of novel PIs, 135 different plant
tissue extracts (leaf, flower and seed) were screened for their PI (trypsin, chymotrypsin and Helicoverpa gut
proteinase inhibitors) activities by using dot-blot assays. Most of the plant tissues screened revealed moderate PI
activity, few showed low PI activity and very few of them showed strong PI activity against trypsin, chymotrypsin
and Helicoverpa gut proteinases. The inhibitory potency of positive samples was further determined by solution
assays. Five plants namely Arachis hypogaea, Vigna sinensis, Dolichos lablab, Phaseolus aureus and Cassia siamea
showed higher activity which ranged from 22.91 to 58.33 %. Higher activities recorded in the seed as compare to leaf
and flower tissues. Dolichos lablab showed highest PI activity (58.33 %) followed by Cassia siamea (52.08 %). PI
activity was found to be distributed unequally in ammonium sulfate (NH2SO4) fractions.