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Singh H.R.,Tocklai Tea Research Institute | Singh H.R.,Institutional Biotech Hub | Deka M.,Gauhati University | Das S.,Tocklai Tea Research Institute | Das S.,Institute of Bioresources and Sustainable Development
Functional and Integrative Genomics | Year: 2015

Tea is the second most consumed beverage in the world. A crop loss of up to 43 % has been reported due to blister blight disease of tea caused by a fungus, Exobasidium vexans. Thus, it directly affects the tea industry qualitatively and quantitatively. Solanum tuberosum class I chitinase gene (AF153195) is a plant pathogenesis-related gene. It was introduced into tea genome via Agrobacterium-mediated transformation with hygromycin phosphotransferase (hpt) gene conferring hygromycin resistance as plant selectable marker. A total of 41 hygromycin resistant plantlets were obtained, and PCR analysis established 12 plantlets confirming about the stable integration of transgene in the plant genome. Real-time PCR detected transgene expression in four transgenic plantlets (T28, C57, C9, and T31). Resistance to biotrophic fungal pathogen, E. vexans, was tested by detached leaf infection assay of greenhouse acclimated plantlets. An inhibitory activity against the fungal pathogen was evident from the detached leaves from the transformants compared with the control. Fungal lesion formed on control plantlet whereas the transgenic plantlets showed resistance to inoculated fungal pathogen by the formation of hypersensitivity reaction area. This result suggests that constitutive expression of the potato class I chitinase gene can be exploited to improve resistance to fungal pathogen, E. vexans, in economical perennial plantation crop like tea. © 2015, Springer-Verlag Berlin Heidelberg.


PubMed | North Bengal University, Tea Research Association, Tocklai Tea Research Institute and CABI South Asia
Type: Journal Article | Journal: Applied microbiology and biotechnology | Year: 2016

India is the second largest producer of black tea in the world. The biggest challenge for tea growers of India nowadays is to combat pests and diseases. Tea crop in India is infested by not less than 720 insect and mite species. At least four sucking pests and six chewing pests have well established themselves as regular pests causing substantial damage to this foliage crop. Various synthetic pesticides are widely used for the management of tea pests in India. Applications of such large quantity of pesticides could cause various problems such as development of resistance, deleterious effects on non-target organisms such as insect predators and parasitoids, upsetting the ecological balance, and accumulation of pesticide residues on tea leaves. There is a growing demand for organic tea or at least pesticide residue free tea in the international market which affects the export price. There is also a higher emphasis of implementation of new regulations on internationally traded foods and implementation of Plant Protection Code (PPC) for tea by the Government of India. This necessitates a relook into the usage pattern of synthetic pesticides on this crop. There are various non-chemical interventions which are being worked out for their sustainability, compatibility, and eco-friendly properties which can gradually replace the use of toxic chemicals. The application of plant extracts with insecticidal properties provides an alternative to the synthetic pesticides. Botanical products, especially neem-based products, have made a relatively moderate impact in tea pest control. Research has also demonstrated the potential of 67 plant species as botanical insecticides against tea pests. The majority of plant products used in pest management of tea in India are in the form of crude extracts prepared locally in tea garden itself, and commercial standardized formulations are not available for most of the plants due to lack of scientific research in the area. Apart from systematic research in this area, to facilitate the simplified and trade friendly registration procedures with quality assurance of the products, there is an increasing need of regulatory authority and national norms in India.


Roy S.,Tocklai Tea Research Institute | Muraleedharan N.,Tocklai Tea Research Institute | Mukhopadhyay A.,North Bengal University
Experimental and Applied Acarology | Year: 2014

Oligonychus coffeae Nietner (Acari: Tetranychidae), the red spider mite (RSM), is a major pest of tea (Camellia sinensis) in most tea-producing countries. Nymphs and adults of RSM lacerate cells, producing minute characteristic reddish brown marks on the upper surface of mature leaves, which turn red in severe cases of infestation, resulting in crop loss. The pest is present on tea all the year round, although numbers vary depending on season. Their number increases as the weather warms up and decreases markedly once rains set in. Under optimal conditions there may be 22 overlapping generations in a year. Parthenogenesis is known to occur; consequently, all mite stages can be found at a given time. Their infestation is mainly confined to the upper surface of the mature leaves and could readily be identified by the bronzing of the leaf. There are several naturally occurring insect predators, such as coccinellid and staphylinid larvae, lacewing larvae, and mite predators, most importantly species of the families Phytoseiidae and Stigmaeidae. Integrated management has been adopted to control this mite pest, involving cultural, mechanical, physical, biological and chemical methods. This review collates the most important works carried out on biology, ecology and management of O. coffeae. Also the scope of future studies for better management of this regular mite pest of tea is discussed. © 2014 Springer International Publishing Switzerland.


PubMed | Tocklai Tea Research Institute and Indian Statistical Institute
Type: Journal Article | Journal: Journal of food science and technology | Year: 2015

The spatial distribution of theaflavin and thearubigin fractions and their impact on black tea quality were investigated using multivariate and geostatistics techniques. Black tea samples were collected from tea gardens of six geographical regions of Assam and West Bengal, India. Total theaflavin (TF) and its four fractions of upper Assam, south bank and North Bank teas were higher than the other regions. Simple theaflavin showed highest significant correlation with tasters quality. Low molecular weight thearubigins of south bank and North Bank were significantly higher than other regions. Total thearubigin (TR) and its fractions revealed significant positive correlation with tasters organoleptic valuations. Tea tasters parameters were significantly and positively correlated with each other. The semivariogram for quality parameters were best represented by gaussian models. The nugget/sill ratio indicated a strong/moderate spatial dependence of the studied parameters. Spatial variation of tea quality parameters may be used for quality assessment in the tea growing areas of India.


Chowdhury P.,Arbovirology Group | Chowdhury P.,Tocklai Tea Research Institute | Topno R.,Arbovirology Group | Khan S.A.,Arbovirology Group | Mahanta J.,Arbovirology Group
Advances in Virology | Year: 2015

West Nile Virus (WNV) is a pathogenic arbovirus that belongs to genus Flavivirus under family Flaviviridae. Till now there are no approved vaccines against WNV for human use. In this study, the effect of two alkylating agents, formaldehyde and β-PL, generally used for inactivated vaccine preparation, was assessed on the basis of antigenic and immunogenic potential of the inactivated WNV. Lineage 5 WNV isolates were inactivated by both formalin and β-PL treatments. Inactivation was confirmed by repeated passage in BHK-21 cell line and infant mice. Viruses inactivated by both the treatments showed higher antigenicity. Immune response in mice model showed serum anti-WNV antibody titre was moderately higher in formalin inactivated antigen compared to β-PL inactivated antigen. However, no significant differences were observed in neutralization antibody titre. In conclusion, we can state that both formaldehyde and β-PL inactivation processes were found to be equally efficient for inactivation of WNV. However, they need to be compared with other inactivating agents along with study on cell mediated immune response. © 2015 Pritom Chowdhury et al.


Khan S.A.,Arbovirology group | Borah J.,Arbovirology group | Chowdhury P.,Tocklai Tea Research Institute | Dutta P.,Arbovirology group | Mahanta J.,Arbovirology group
Transactions of the Royal Society of Tropical Medicine and Hygiene | Year: 2015

Background: Japanese encephalitis virus (JEV) is one of the major etiological agents responsible for causing large numbers of acute encephalitis syndrome (AES) cases in the northeastern region of India. This study was carried out to establish and characterize the circulating strain of JEV in the region in order to understand the disease epidemiology. Methods: Virus isolation was attempted from 121 patients that presented with AES. Phylogenetic analysis was done using the Kimura-2-Parameter model based on envelope and pre-membrane gene sequence. A pathogenecity study was done in the Swiss albino mice model and assessed by Kaplan-Meier survival analysis. Results: The phylogenetic analysis of the two JEV isolates obtained placed them within genotype (G)III, where they form a subclade within the Vellore group of Indian JEV strains. Neutralization assays suggested similarity between the study isolates and prototype Vellore JEV strain P20778. Pathogenesis in mice suggested that the circulating GIII JEV strains were neuroinvasive. Conclusions: This study showed that a pathogenic GIII JEV strain was circulating in the northeastern region of India. This finding is important as it is contrary to the belief that GI is gradually replacing GIII as the dominant genotype in Asia. © The Author 2015.


Roy S.,Tocklai Tea Research Institute | Rahman A.,Tocklai Tea Research Institute
Zoology and Ecology | Year: 2014

The tea aphid Toxoptera aurantii Boyer (Sternorrhyncha: Aphididae) is a major pest of the tea plant (Camellia sinensis (L.)). Micraspis discolor (F.) and Menochilus sexmaculatus (F.) (Coleoptera: Coccinellidae) are the most common predators of these pests in tea plantations of North East India. A laboratory study was conducted to evaluate the suitability of the tea aphid Toxoptera aurantii, as prey for these two ladybird beetles. The life cycle of M. sexmaculatus was found to be shorter than that of M. discolor. Aphid consumption by M. sexmaculatus was significantly higher than that by M. discolor. Aphid consumption by larvae of M. discolor and M. sexmaculatus was noticed to be higher in later instars. Females of both ladybird species consumed a significantly greater number of aphids per day than males. As for biological parameters and the predatory potential of the two ladybird species, the study results proved that M. discolor and M. sexmaculatus are effective biocontrol agents of the tea aphid and can be used in integrated pest management programs successfully. © 2014 Nature Research Centre.


Pramanik P.,Tocklai Tea Research Institute | Safique S.,Tocklai Tea Research Institute | Jahan A.,Tocklai Tea Research Institute | Bhagat R.M.,Tocklai Tea Research Institute
Ecological Engineering | Year: 2016

Pruning of tea (Camellia sinensis L.) bushes (plants) generates tonnes of plant biomass in each tea garden; however, the hard nature of stems present in pruning litters limits its use in agriculture as an organic amendment. The pruning litters contain more than 1% total nitrogen (N) and the objective of this study was to evaluate the possibility of recycling prunings of tea gardens to nutrient-rich soil amendment through vermicomposting and to modify the vermicomposting technique for replacing the addition of cattle manure with partially decomposed plant (easily available weeds or wastes) residues. In this study, mixing of cattle manure with shredded prunings decreased the rate of vermicomposting and the completion of vermicomposting required one month (30 days) more than the time required for vermicomposting of chopped prunings and cattle manure combination. The extra time required for vermicomposting might be attributed to the decomposition of hard prunings in shredded form. Shredding of prunings significantly (P ≤ 0.05) decreased total organic C content and that in turn significantly (P ≤ 0.05) increased total concentrations of nitrogen, phosphorus and potassium in the final vermicompost. Enhanced cellulolytic microbial population and cellulase activity might be attributed to the enhanced decomposition of shredded pruning wastes. The study indicated that partially decomposed plant residues like that of guatemala leaves may be used as alternative of cattle manure during vermicomposting of shredded pruning wastes and total concentrations of nitrogen, phosphorus and potassium in those vermicomposts were significantly at par with those prepared from pruning wastes and cattle manure. © 2016 Elsevier B.V.


Das S.,Tocklai Tea Research Institute | Borua P.K.,Dibrugarh University | Bhagat R.M.,Tocklai Tea Research Institute
Organic Agriculture | Year: 2016

The effects of organic (OFS) and conventional (CFS) farming systems on soil nitrogen and tea (Camellia sinensis L.) leaf physiological as well as biochemical properties under humid sub-tropical conditions were studied at the experimental field of Tocklai Tea Research Institute, Jorhat, Assam, India. A part of the field under CFS was converted to organic in 2008 by using different organic manures, viz., vermicompost, P-enriched vermicompost, de-oiled neem cake, and inserting green crop, besides phosphorous (P) and potassium (K) solubilizing bacteria. After 4 years of conversion process, OFS resulted in significantly higher values for leaf total catechin (262.03 mg g−1), (−)-epigallocatechin gallate (EGCG, 159.97 mg g−1), and (−)-epicatechin gallate (ECG, 42.93 mg g−1) contents although there was up to 22 % reduction in tea yield. On the other hand, CFS resulted in significantly higher values for soil available nitrogen (154 mg kg−1) contents as well as for leaf chlorophyll a (2.51 mg kg−1), chlorophyll b (1.02 mg kg−1), and total chlorophyll (3.53 mg kg−1), contents. No significant difference was observed for caffeine, (−)-epigallocatechin (EGC), (+)-catechin (C), and (−)-epicatechin (EC) contents between the two farming systems studied. Correlation analysis indicated that (−)-EGCG was the major catechin fraction significantly correlated with leaf chlorophyll a, chlorophyll b, and total chlorophyll contents. The present study has provided knowledge on soil available nitrogen as well as leaf physiological and biochemical contents in tea shoots under humid sub-tropical conditions in Northeast India. © 2015, Springer Science+Business Media Dordrecht.


PubMed | Tocklai Tea Research Institute
Type: Journal Article | Journal: Bioinformation | Year: 2015

MADS (Minichromosome Maintenance1 Agamous Deficiens Serum response factor) box genes encode transcription factors and they play a key role in growth and development of flowering plants. There are two types of MADS box genes- Type I (serum response factor (SRF)-like) and Type II (myocyte enhancer factor 2 (MEF2)-like). Type II MADS box genes have a conserved MIKC domain (MADS DNA-binding domain, intervening domain, keratin-like domain, and c-terminal domain) and these were extensively studied in plants. Compared to other plants very little is known about MADS box genes in Camellia sinensis. The present study aims at identifying and analyzing the MADS-box genes present in Camellia sinensis. A comparative bioinformatics and phylogenetic analysis of the Camellia sinensis sequences along with Arabidopsis thaliana MADS box sequences available in the public domain databases led to the identification of 16 genes which were orthologous to Type II MADS box gene family members. The protein sequences were classified into distinct clades which are associated with the conserved function of flower and seed development. The identified genes may be used for gene expression and gene manipulation studies to elucidate their role in the development and flowering of tea which may pave the way to improve the crop productivity.

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