Dipjyoti Chakraborty

Proteomic analysis of salicylic acid induced resistance to Mungbean Yellow Mosaic India Virus in Vigna mungo

The role of salicylic acid (SA) in inducing resistance to MYMIV infection in Vigna mungo has been elucidated by proteomics. Twenty-nine proteins identified by MALDI-TOF/TOF, predicted to be involved in stress responses, metabolism, photosynthesis, transport and signal transduction, showed increased abundance upon SA treatment. Susceptible plants showed characteristic yellow mosaic symptoms upon MYMIV infection. A concentration dependent decrease in physiological symptoms associated with MYMIV was observed upon exogenous SA treatment prior to viral inoculation; and no visible symptom was observed at 100 μM SA. SA treatment stimulated SOD and GPX activity and inhibited CAT activity thus preventing ROS mediated damage. Significant increase in chlorophyll, protein, carbohydrate, phenolic content and H(2)O(2) were observed. Involvement of calmodulin for transmission of defense signal by SA is suggested. A metabolic reprogramming leading to enhanced synthesis of proteins involved in primary and secondary metabolisms is necessary for SA mediated resistance to MYMIV. Identification of proteins showing increased abundance, involved in photosynthetic process is a significant finding which restores virus-induced degradation of the photosynthetic apparatus and provides enhanced metabolites required for repartition of resources towards defense.

Plasmodium falciparum: In vitro interaction of quassin and neo-quassin with artesunate, a hemisuccinate derivative of artemisinin

Quassia amara L. (Family Simaroubaceae) is known to have several medicinal properties including the activity against malaria. An HPLC method was employed for purification of the biologically active quassinoids; quassin (Q) and neo-quassin (NQ), further characterized by MALDI-TOF analyses. Purified Q, NQ and the crude bark extract (S1) along with artesunate (AS) were studied for their in vitro anti-plasmodial activity. The in vivo toxicity studies at intraperitoneal doses with higher concentrations of the crude bark extract (S1) in Balb/C mice ruled out the apprehension of toxicity. Interaction studies between the test compounds among themselves (Q+NQ) and individually with artesunate (AS+Q, AS+NQ), were carried out in vitro at four ratios (1:5, 1:2, 2:1 and 5:1) on chloroquine sensitive (MRC-pf-20) and resistant (MRC-pf-303) strains of Plasmodium falciparum. The crude bark extracts of Q. amara exhibited higher P. falciparum inhibitory activity (IC(50)=0.0025 microg/ml) as compared to that of the isolated compounds, quassin (IC(50)=0.06 microg/ml, 0.15 microM), neo-quassin (IC(50)=0.04 microg/ml, 0.1 microM) and also to the positive control, artesunate (IC(50)=0.02 microg/ml, 0.05 microM). The in vitro drug interaction study revealed the compounds, quassin and neo-quassin to be additive to each other. At lower ratios, artesunate was found to be a potential combination partner with both the compounds. It was interesting to note that none of the combinations exhibited antagonistic interactions. This phenomenon offers the opportunity for further exploration of novel therapeutic concentrations and combinations.

Analysis of Biochemical Responses in Vigna Mungo Varieties Subjected to Drought Stress and Possible Amelioration

A complex response (in terms of physiological, biochemical and molecular level) is shown by plants exposed to drought and depending on that, plants show differential adaptation and tolerance mechanisms. Drought stress effects on plants are generally evident in terms of reduced growth, loss of membrane stability and integrity, reduction in essential pigments like chlorophyll etc. The pulse crops black gram (Vigna mungo L.) is an important protein source that is grown in all over India. In addition, it also plays an important role in sustaining soil fertility by fixing atmospheric nitrogen. However, productivity is adversely affected by various biotic and abiotic stresses necessitating screening of newer varieties for better adaptation to local conditions. In the present study, three varieties of Vigna mungo, viz., IPU 94-1, PU 40 and PU 19, widely grown in the northern India were evaluated for their response to short term drought stress at early growth stage. Drought stress had detrimental effect in several biochemical parameters like chlorophyll content, lipid peroxidation, oxidative stress, generation of H2O2. Modulations of several metabolic components like phenolics, proline and antioxidant enzymatic responses of superoxide dismutase, peroxidase and catalase were observed in drought and recovery to combat the stress.

Induction of nodD Gene in a Betarhizobium Isolate, Cupriavidus sp. of Mimosa pudica, by Root Nodule Phenolic Acids.

Abstract A range of phenolic acids, viz., p-coumaric acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, protocatechuic acid, caffeic acid, ferulic acid, and cinnamic acid have been isolated and identified by LC–MS analysis in the roots and root nodules of Mimosa pudica. The effects of identified phenolic acids on the regulation of nodulation (nod) genes have been evaluated in a betarhizobium isolate of M. pudica root nodule. Protocatechuic acid and p-hydroxybenzoic acid were most effective in inducing nod gene, whereas caffeic acid had no significant effect. Phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase activities were estimated, indicating regulation and metabolism of phenolic acids in root nodules. These results showed that nodD gene expression of betarhizobium is regulated by simple phenolic acids such as protocatechuic acid and p-hydroxybenzoic acid present in host root nodule and sustains nodule organogenesis.

Salicylic Acid and Drought Stress Response: Biochemical to Molecular Crosstalk

Salicylic acid, a naturally occurring phenolic compound, is a multifaceted plant growth modulator and activates the systemic acquired defence in plants as a response to pathogen effect. In recent years in addition to the activation of SAR, SA is reported to play a major role in the modulation of plant responses to biotic and abiotic stresses like drought, salinity, heat, heavy metal stress, osmotic stress, defence against pathogenic elicitors and effectors and symbiotic relationships. Additionally, SA has well laid out physiological roles in growth and development of plants. Several of the targets of SA have been recognized, and the molecular mode of action elucidating the complex signal transduction and involving crosstalk of multiple metabolic pathways is being unravelled. This chapter deals with recent findings on the improvement of drought tolerance vis-a-vis salicylic acid-induced modulation of metabolic pathways and signalling mechanisms.

Antifungal Activity of Medicinal Plants Leaf Extracts on Growth of Macrophomina phaseolina

Macrophomina phaseolina (Tassi goid) is a pathogen that causes Charcoal rot of mungbean resulting in to a great economic loss. In the present study effect of Ocimum sanctum L., Calotropis procera (Ait.) Ait. f. and Astragalous tribuloides Delile extract on the survival of Macrophomina phaseolina was studied. The variety of different extracts of Ocimum sanctum L., Calotropis procera (Ait.) Ait.f and Astragalous tribuloides Delile brings various biochemical changes under suitable condition. The alkaline extract of Ocimum sanctum L., shows the maximum growth of Macrophomina phaseolina, Acidic extract of Calotropis procera (Ait.) Ait. f. and alcoholic extract of Astragalous tribuloides Delile show maximum growth of Macrophomina phaseolina. It showed that Macrophomina phaseolina was less reactive in these extract. On the other hand, aqueous acidic extract of Ocimum sanctum L., alkaline extract of Calotropis procera (Ait) Ait. f. and acidic extract of Astragalous tribuloides Delile showed minimum growth of Macrophomina Phaseolina. It indicated that Macrophomina phaseolina was more reactive in these plant extract.

Response of Plants to Salinity Stress and the Role of Salicylic Acid in Modulating Tolerance Mechanisms: Physiological and Proteomic Approach

Salinity is one of the most consequential stresses, which limits the productivity of agricultural crops and affects germination, plant strength, and crop yield. High salinity affects plants in several ways, such as water stress, ion toxicity, oxidative stress, alteration of metabolic processes, nutritional disorders, membrane disorganization, and reduction of cell division, expansion, and genotoxicity.