Papers by Usha Chakraborty
NBU Journal of Plant Sciences
Grey blight disease caused by Pestalotiopsis disseminata, is one of the major foliar fungal disea... more Grey blight disease caused by Pestalotiopsis disseminata, is one of the major foliar fungal diseases that constantly affects Persea bombycina Kost, a primary host plant of muga silkworm. Under nursery condition, grey blight disease was recorded mostly in SS and S6 morphotypes of som plants. Vermicompost, PGPR and AMF, alone and in combination were applied for the improvement of the growth of eight morphotypes of som plant as well as to reduce incidence. Growth in terms of height (cm), no. of leaves and no. of branches were studied. Analysis of some major defence related enzymes such as POX, PAL, CHT and GLU was also carried out to check induction of resistance after treatment. Artificial inoculation of som plants under nursery condition with spore suspension of P. disseminata was performed and disease progression noted for 7, 14, 21 and 28 days. It was clearly seen that disease progression was slow and less in treated inoculated plants. The results emphasize the fact that applicatio...
Journal of Mycopathological Research, 2015
Journal of Mycopathological research
Postbloom fruit drop of Citrus reticulata was noticed in fields during early development of fruit... more Postbloom fruit drop of Citrus reticulata was noticed in fields during early development of fruits. Disease symptoms appeared as round brownish black spots, lesions are usually surrounded by yellow aureole. Black lesion can be seen after peeling the fruit, thereby reducing the value of fruit for the fresh market. Fungal pathogen isolated from infected fruit was identified as Alternaria alternata disease symptom by the isolated pathogen was established in healthy mandarin fruit following completion of Koch's postulate. Morphological and molecular identification confirmed the pathogen as Alternaria alternata , which is the first report of postbloom fruit drop of Citrus reticulata in India. Genomic DNA was prepared from A. alternata, purified and PCR amplification of 18S rDNA was done using ITS region specific primer pair. The product size was approximately 544 bp. Phylogenetic tree based on the neighbor-joining analysis of gene sequences of A. alternata from citrus (IPL.CIT.A.F1.001) showed satisfactory homology with 16 ex type strains of Alternaria alternata sequences from NCBI GenBank data base.
In present decade Mushroom is considered as a crucial component for food safety and security. Mic... more In present decade Mushroom is considered as a crucial component for food safety and security. Micro -economy and community engagement in mushroom cultivation is helping rural economy of North Bengal. Calocybe indica an edible mushroom, native to India was to boost first described by Purkayastha and Chandra (1974). Its milky white colour and robust appearance is appealing to all and provided with easy, reliable, renewable method of growing, its popularity is bound to increase. Since this mushroom has not been cultivated in North Bengal region earlier, in the present study we report the attempts made to establish the cultivation here and hence popularize its commercial cultivation. Paddy straw was used as Substrate which was found to be suitable for growing Calocybe indica. The spent mushroom substrate (SMS) is the leftover of wastes after different flushes of mushrooms have been harvested. Spent mushroom substrate of milky mushroom was tested on the growth and development of some lea...
Acta Horticulturae, 2011
Mandarin (Citrus reticulata) is an ancient commercial crop being cultivated in Darjeeling and Sik... more Mandarin (Citrus reticulata) is an ancient commercial crop being cultivated in Darjeeling and Sikkim hills. Decline in general plant health and decreased fruit production as influenced by abiotic and biotic factors is a major threat to the cultivators in the region. Bacillus pumilus TRS 3, a potential plant growth promoting rhizobacterium, isolated from rhizosphere of plantation crop, which showed phosphate solubilization, siderophore production, IAA and volatile production in vitro, when applied to the rhizosphere of nursery grown mandarin seedlings, enhanced growth markedly. Plant growth promotion was determined in terms of increase in height of plants, number of leaves and biomass. B. pumilus also showed antagonism against fungal pathogens in vitro. In addition, screening of arbuscular mycorrhizal fungi from rhizosphere of mandarin plants yielded predominant association of Glomus mosseae, G. fasciculatum, G. intradices, G. versiforme, Gigaspora margarita, G. rosea, G. gigantea along with Acaulospora spinosa, A. bireticulata and Scutellospora sp. Maximum colonization by G. mosseae was evident which was selected for mass multiplication in maize plants. Mandarin roots were inoculated with G. mosseae alone and in combination with B. pumilus which was applied as soil drench. Both microorganisms increased growth of the plants but most significant increase was obtained when both were co-inoculated. Similarly, root rot of mandarin caused by Fusarium oxysporum, was suppressed to certain extent by B. pumilus or G. mosseae, but significant suppression occurred when G. mosseae was co-inoculated with B. pumilus. Three major enzymes involved in defense, chitinase, β-1,3 glucanase and peroxidase showed enhanced activities during disease suppression, which was also confirmed by immunological assays such as PTA-ELISA and Dot-blot. Observed plant health improvement and disease suppression in mandarin plants may be due to a combination of at least three mechanisms-direct inhibition of the pathogen in the soil, induction of resistance in the host or better nutrient availability.
ABSTRACT: The present in vitro study was carried out to screen such beneficial rhizobacterial iso... more ABSTRACT: The present in vitro study was carried out to screen such beneficial rhizobacterial isolates that could be utilised for improvement of growth of som plant (Persea bombycina Kost.), a primary food source of the muga silkworm. Rhizobacteria was isolated from the rhizospheric soil collected from the som germplasm conservation site located at Regional Muga Research Station, Central Silk Board, Boko, Assam (GPS location 25.990 N, 91.250 E). Sixty-one percent of the total 18 isolates showed phosphate solubilisation as well as NH3 production. On the contrary, fewer isolates (33%) produced Indole Acetic Acid in vitro. Majority of the isolates showed resistance to Penicillin and Vancomycin at concentrations >10mcg. In addition, some of the isolates depicted antagonistic activity against Pestalotiopsis disseminata and Phyllosticta persea, the two phytopathogens responsible for causing grey blight and leaf spot diseases respectively in P. bombycina. Molecular identification of two...
Indian Phytopathology
The present review deals with the serological and molecular techniques available for detection of... more The present review deals with the serological and molecular techniques available for detection of fungal pathogens in plants, followed by management practices using bioinoculants which can induce resistance in the hosts. Specific detection of pathogens in the plant tissues even before the appearance of symptoms are done either through protein based immunodiagnostic techniques or DNA/RNA based molecular techniques. Immunotechniques depend on specific interaction between antigen of the pathogen or infected tissues and antibodies prepared against the specific antigen. Positive reactions are detected through either qualitative or quantitative techniques. Among the immunodiagnostic techniques, the most widely and commonly used is the enzyme linked immunosorbent assay (ELISA), Dot blot, Western blot and Immunofluorescence. The molecular techniques are predominantly PCR based and include different variations with increasing sensitivity such as nested PCR, multiplex PCR, reverse transcriptase PCR, real time PCR, loop-mediated isothermal amplification (LAMP) and nano based PCR. Thus, by use of one or more sophisticated techniques it is possible to detect pathogens rapidly and specifically. Pathogen detection is generally followed by management techniques, and in the current scenario ecologically safe bioinoculants are used for induction of immunity in the plants. There are several bioinoculants based on beneficial microorganisms such as plant growth promoting bacteria, biocontrol agents and arbuscular mycorrhizal fungi. Application of these microorganisms, singly or as a consortium, has been reported to induce immunity in plants. Induced systemic resistance (ISR) operates through signal molecules and pathways involving jasmonate and ethylene, and in very few cases, salicylate. Upregulation of these pathways leading to enhanced accumulation of antimicrobial compounds (phytoalexin) help in warding off the pathogen during subsequent attack.
NBU Journal of Plant Sciences
The development of molecular techniques for genetic analysis has led to a great increase in our k... more The development of molecular techniques for genetic analysis has led to a great increase in our knowledge of plant genetics and our understanding of the structure and behaviour of plant genome. During last three decades, several powerful DNA based marker technologies have been developed for the assessment of genetic diversities and molecular marker assisted breeding technology. In plant systems, the prospects of DNA profiling and fingerprinting is becoming indispensable in the context of establishment of molecular phylogeny, assessment of somaclonal variants, characterization of plant genomics, marker- based gene tags, map-based cloning of agronomically important genes, variability studies, synteny mapping, marker-assisted selection of desirable genotypes etc. In this review article, various molecular markers are reviewed with emphasis on specific areas of their application in higher plants.
NBU Journal of Plant Sciences
Induced heat-tolerance triggered by heat acclimation treatment and foliar application of salicyli... more Induced heat-tolerance triggered by heat acclimation treatment and foliar application of salicylic acid and abscisic acid were evaluated in three different genotypes of chickpea (Cicer arietinum L.) distinctly differing in their sensitivity to heat stress. Seedlings pre-treated with 100uM salicylic acid (SA) and 50 uM abscisic acid (ABA) showed improved heat tolerance to a lethal temperature of 46°C than the untreated control seedlings. Heat stress increased lipid peroxidation of membranes and reduced plant survival. Protein and proline contents increased significantly in pre-treated seedlings. Cell membrane stability also increased remarkably in pre-treated seedlings of all three genotypes. Changes in activities of antioxidative enzymes like peroxidase, ascorbate peroxidase in pre-treated seedlings revealed increase in enzymatic activities which declined sharply at lethal temperuturc. Quantum of increase in enzymatic activity was however higher in thermotolerant genotype in compari...
NBU Journal of Plant Sciences
Salt glands in Poaceae are often found in the Panicoid and Chloridoid grasses. Imperata cylindric... more Salt glands in Poaceae are often found in the Panicoid and Chloridoid grasses. Imperata cylindrica is a perennial panicoid grass with widespread distribution from non-saline to saline habitats. The efficient mechanism of salt gland is an essential property of the salt tolerance of any plant. Salt glands in Imperata are present and actively function to remove the toxic Na+ ion from the cytoplasm of the mesophyll cells. SEM study reveal the presence of salt glands in both control and NaCl treated plants (200 mM NaCl for 3 days), but the density of salt glands is more in NaCl treated leaf samples. Also the vacuolarization of the cells is an important attribute for the sequestration of excess Na+ ion. The concerted activity of these two mechanisms in Imperata is important for maintaining osmotic balance inside the cells. The time dependent lowering of H202 and O2 and increased accumulation of proline under NaCl stress was also observed in Imperata. This accounts for a favourable environ...
NBU Journal of Plant Sciences
Two wheat cultivars, viz. C306 and HT41, have been evaluated for their responses to heat stress i... more Two wheat cultivars, viz. C306 and HT41, have been evaluated for their responses to heat stress in terms of some biochemical and physiological attributes. During the exposure to high temperature (40°C for 6 and 12 h), a significant reduction in RWC and FW was recorded in HT41 which was also associated with heat susceptibility. The detrimental effects of high temperature were also apparent in terms of lipid peroxidation, chlorophyll content, H2O2 generation and electrolyte leakage and these were more pronounced in HT 41. Accumulation of osmolytes like proline, total sugar increased due to heat injury and also varied between the two cultivars. In this present study evaluation and analysis of these biochemical and physiological characters under heat stress could unravel the mechanism of basal thermotolerance and thus might be useful as genetic stock to develop wheat tolerant varieties.
NBU Journal of Plant Sciences
The effect of the aqueous extract of Moringa oleifera Lamk. leaves (MOLE) in the treatment of dia... more The effect of the aqueous extract of Moringa oleifera Lamk. leaves (MOLE) in the treatment of diabetes along with its antioxidant activity in streptozotocin induced diabetic rats was determined in the current study. Oral administration of MOLEt @ 125 and 250 mg/kg for 20 days significantly prevented the STZ- induced hyperglycemia. Administration of the extracts at the dose of 250 mg/kg body weight/day resulted in a marked decrease in the levels of fasting blood glucose and urine sugar. The extract also produced a significant decrease in peroxidation products, viz.. thiobarbituric acid reactive substances. The activity of reduced glutathione and glycogen content were found to be increased in the hepatic tissue of SiZ- diabetic rats treated with MOLEL. STZ-diabetic rats treated with MOLEt significantly reversed all these changes to near normal. The MOLBt thus exhibits antidiabetic and anti-oxidative activity in STZ-induced diabetic rats.
NBU Journal of Plant Sciences
Reactive oxygen species (ROS) include oxygen ions, free radicals and peroxides both inorganic and... more Reactive oxygen species (ROS) include oxygen ions, free radicals and peroxides both inorganic and organic. They are generally very small molecules and are highly reactive due to the presence of unpaired valence shell electrons. ROSs form as a natural byproduct of the normal metabolism of oxygen and have important roles in cell signaling. While ROS have the potential to cause oxidative damage to cells during environmental stress, recent studies have shown that ROS play a key role in plants as signal transduction molecules involved in mediating responses to pathogen infection, environmental stresses, programmed cell death and developmental stimuli. The rapid increase in ROS production, referred to as 'the oxidative burst', was shown to be essential for many of these processes, and genetic studies have shown that respiratory burst oxidase homolog (Rboh) genes, encoding NADPH oxidases, are the main producers of signal transduction-associated ROS in cells during these processes.
Tropical Grasslands-Forrajes Tropicales
The salt tolerance of 12 native forage grasses from the eastern part of Terai-Duar grasslands was... more The salt tolerance of 12 native forage grasses from the eastern part of Terai-Duar grasslands was assessed using a rapid method of leaf disc senescence bioassay. Samples of these grasses were grown in untreated water as well as 100 and 200 mM NaCl solutions for periods of 3, 6 and 9 days. Discs of fresh leaf were then placed in untreated water as well as in 100 and 200 mM NaCl solutions for 96 hours. Quantitative effects were measured as the effects on chlorophyll concentration in leaves in response to exposure to the varying solutions. From these results, the salt sensitivity index (SSI) of the individual grasses was determined. The SSI values indicated that Imperata cylindrica, Digitaria ciliaris and Cynodon dactylon were most salt-tolerant of all grasses tested. Further characterization of the grasses was done by observing the changes in 6 biomarkers for salinity tolerance: relative water content, total sugar concentration, proline concentration, electrolyte leakage, membrane lipid peroxidation and H2O2 concentration following exposure to 100 and 200 mM NaCl concentrations for 3, 6 and 9 days. Finally, hierarchical cluster analysis using the software CLUSTER 3.0 was used to represent the interrelations among the physiological parameters and to group the grasses on the basis of their salinity tolerance. The overall results indicated that Imperata cylindrica, Eragrostis amabilis, Cynodon dactylon and Digitaria ciliaris were potentially salt-tolerant grasses and should be planted on saline areas to verify our results. On the other hand, Axonopus compressus, Chrysopogon aciculatus, Oplismenus burmanni and Thysanolaena latifolia were found to be highly salt-sensitive and would be unsuitable for use in saline areas.
Indian phytopathology, 2016
Eight different morphotypes (S1-S8) of Persea bombycina , locally known as som plant, were grown ... more Eight different morphotypes (S1-S8) of Persea bombycina , locally known as som plant, were grown in pots under nursery condition where the soil was supplemented with varieties of bio-inoculants like Plant Growth Promoting Rhizobacteria (PGPR), Arbuscular Mycorrhizal Fungi (AMF) and Plant Growth Promoting Fungi (PGPF) alone or in combinations. Among these eight morphotypes, S5 and S6 showed improved growth. These two morphotypes were further transplanted in field where the soil was amended with talc-based formulation of Bacillus altitudinus , wheat bran based formulation of Trichoderma asperellum and mass multiplied spores of AMF. Enhancement of growth was evidenced in treated plants by increase in plant height (cm), total number of branches and number of leaves. Following the application of these bioformulations, soil phosphate content decreased and root phosphate increased in case of treated plants. Increase in chlorophyll content as well as total soluble protein content of the lea...
Journal of Tea Science, 2012
Glomus fasciculatum , one of the dominant arbuscular mycorrhizal fungus (AMF) associated with tea... more Glomus fasciculatum , one of the dominant arbuscular mycorrhizal fungus (AMF) associated with tea root colonization, was selected and maintained in maize plants. Besides AMF, Bacillus amyloliquefaciens TRS6 isolated from tea rhizosphere, which showed in vitro antagonism to a number of tea root rot pathogens as well as siderophore-producing and phosphate-solubilizing activities, was selected for utilization as bioinoculants in tea plants for improvement of health status. The bacterium was applied to the soil as aqueous suspensions, and in case of G. fasciculatum , soil was inoculated with its spores and in joint inoculations, the AMF was inoculated prior to the bacterium. Inoculation of rhizosphere of tea plants of six different varieties (TV-18, T-17, AV-2, T-78, UP-3 and UP-26) with any of two microorganisms increased growth of plants, but the most significant increase was obtained in dual application. Plant growth was measured in terms of increase in height, increase in number of ...
Free radicals are responsible for many oxidative stress related diseases. Antioxidants are those ... more Free radicals are responsible for many oxidative stress related diseases. Antioxidants are those substances capable of scavenging free radicals and in recent years, antioxidants of plant origin are gaining interest globally. Ferns are an interesting group of plants, many of which still remain unexplored in the area of phytochemical properties. Thus, the present study was carried out to quantify the phytochemicals and evaluate the in vitro antioxidant activity of fertile fronds of Drynaria quercifolia, a common fern growing in this region. Methanolic (MeOH), ethanolic (EtOH) and hot water (HW) extracts were used for determination of antioxidative activity. Results revealed the presence of phenol, flavonoid, vitamin C and E in the sample. MeOH extract showed higher antioxidative activity in comparison to the EtOH and HW extract in dose-dependent manner. However, DPPH was seen to be scavenged slightly better by HW extract. From the overall data it can be concluded that methanolic extra...
Journal of Tea Science, 2011
Various phytochemical constituents including alkaloids, phenols, and ascorbic acids were assessed... more Various phytochemical constituents including alkaloids, phenols, and ascorbic acids were assessed and compared in the four medicinal plants of different families. Four plants used locally for different medicinal purposes were selected for a comparison of their phytochemical constituents. The plants investigated were Clerodendrum viscosum , Moringa oleifera , Cinnamomum tamala and Scoparia dulcis . All theses plants were found to contain the active principles including alkaloids, tannin, saponin, terpenoid, flavonoid, cardic glycoside. Steroid was present in C . viscosum, C. tamala, and M. oleifera but absent in S. dulcis. The assay for the quantitative determination of phenols and ascorbic acids revealed that C. tamala contained the highest amount of phenol and ascorbic acids where as C. viscosum contained the least amount.
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Papers by Usha Chakraborty