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Assam Agricultural University, Jorhat

Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level. Genesis of AAU - The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati. Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.

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Subject: Agricultural Biotechnology × End date: 2018 × Start date: 2018 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    A study on the role of exopolysaccharide in conferring acid tolerance in Bacillus sp.
    (AAU, Jorhat, 2018-01) Deka, Priyadarshini; Barooah, Madhumita
    Soil bacteria have evolved various mechanisms to adapt to stress environmental conditions such as temperature, salinity, drought and low pH condition of soil. Among the several environmental stress conditions, soil acidity an important factor influencing physicochemical and biological properties of soil along with microbial diversity and crop production is an emerging issue of immense concern due to its wide spread distribution across the globe. Although low soil pH restricts the number and diversity of bacteria, it is known that some soil bacteria are able to thrive in such conditions having evolved various mechanisms including production of biofilm to circumvent acid stress. Bacterial exopolysaccharide (EPS) are high-molecular-weight complex polymers composed of sugar moieties that form the main component of the biofilm which aid the bacteria to colonize substrata. In the present study, a total of 28 isolates were identified and characterized as acid tolerant EPS producing bacteria among which, B. amyloliquefaciens p16 produce the highest EPS (219.96 μg/ml). A culture medium containing sucrose (3.5%) as carbon source with pH 5.0 and incubated for 24 hrs was optimal for maximum production of EPS. The HPLC analysis of monomeric units of EPS produced by B. amyloliquefaciens p16 revealed the abundance of galactose at pH 7.0 which however, changed to arabinose when shifted to acidic condition (pH to 5.0 and 4.5). The isolate B. amyloliquefaciens p16, significantly improved soil physical properties in terms of greater soil aggregation (80.59 mm diameter aggregates) and water holding capacity (53.90%) when inoculated into soil over the control (31 mm diameter aggregates and 18.21%, respectively). The differential expression of epsA and epsB, the first two genes of the eps operon showed a 7 and 9 fold increased expression in pH 5.0 compared to pH 7.0 respectively. Disruption of the epsB gene in B. amyloliquefaciens p16 using integration vector pMUTIN4 generated mutants that produced significantly lesser EPS (33.23 μg/ml) when compared to the WT (223.87 μg/ml). The generated mutant of B. amyloliquefaciens p16 lacking the wrinkled morphology had an extended lag phase of 24 hrs and was barely able to survive in acidic medium (pH 4.5) unlike that of the WT type. Soil inoculated with generated mutants formed smaller soil aggregates (42.41±1.70 mm) and had decreased water holding capacity (27.67±1.94%) compared to the WT (80.59± 0.22 mm and 53.90± 1.66%, respectively). This study indicates that EPS secreted by acid tolerant bacteria (B. amyloliquefaciens p16) imparts acid tolerance and also aids in improving the soil physical structure through increased soil aggregation and water holding capacity.
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    ThesisItemOpen Access
    Study and characterization of the DNA virus diseases in few important crops of Assam
    (AAU, Jorhat, 2018-01) Baldodiya, Gajendra Mohan; DebNath, Palash
    Plant viruses cause many devastating diseases and are responsible for the huge loss in crop production and quality. The Infected plants may show a range of symptoms like leaf yellowing, leaf distortion, growth abnormalities and yield reduction. Although the majority of the plant viruses are RNA viruses, in the recent years, DNA viruses have emerged as a serious problem for vegetables and fiber crops, more specifically in tropical and subtropical regions of the world. In India, Begomoviruses are known for major yield loss in a variety of crops. So far, very few reports on DNA virus diseases are available from the northeastern region, including Assam. In the present study, three important single-stranded DNA viruses, banana bunchy top virus (BBTV), squash leaf curl China virus (SLCCNV) and tobacco curly shoot virus (TbCSV) were identified from Assam infecting banana, pumpkin, and chilli crops respectively. The crop cultivating areas were surveyed and 89 plant samples showing symptoms of geminivirus and BBTV infections were collected from 16 different crops. The broad-spectrum antibody combination, tomato yellow leaf curl virus (TYLCV) in DAS-ELISA (double antibody sandwich ELISA) assay revealed the all possible Begomovirus infections. The molecular detection method by using universal and gene-specific primers confirmed the presence of viral genome in positively screen samples through DAS-ELISA. The full-length genome amplification of detected viruses was achieved by designing walking primers from both ends of the partial genome and rolling circle amplification (RCA) followed by cloning process. The in silico analysis (genomic feature analysis, multiple sequence alignment and phylogenetic grouping) revealed the molecular properties of identified viruses. The BBTV-As-JOR was found closely related with BBTV-Lucknow isolate, although it stands out for few genomic features. Each genomic segment of the BBTV-As-JOR isolate was comprised of an ORF in sense orientation, encoding specific protein like other BBTV isolates. The common region major (CR-M) of DNA-R shows 26nt deletion like BBTV Lucknow but deletion of 36nt in DNA-U3 was found different. The BBTV-As-JOR clustered with PIO (Pacific Indian Ocean) isolates in the phylogenetic analysis based on the R-segment. Similarly, the clustering of other BBTV segments was also found with previously reported BBTV isolates of PIO group. The genome of SLCCNV-As-JOR-G8 pumpkin shared high nucleotide sequences and proteins similarity with SLCCNV-pumpkin-Varanasi DNA-A. The phylogenetic clustering also conferred these findings. The sequence analysis confirmed the presence of seven ORFs viz, AC1, AC2, AC3, AC4, AC5, AV1/CP and AV2 in SLCCNV-As-JOR-G8 pumpkin. The ORFs showed the typical begomoviral genome organization; however, they displayed similarity to different begomoviruses. The TbCSV-As was identified as a close relative of TbCSV)-[SC118] sharing the similarity of two major proteins, AL2 and AL3. The occurrence of TbCSV in chilli (Capsicum frutescens) host plant and causing upward curling of leaves is the first report from India in our knowledge. This study presents the first report of identification and characterization of BBTV, SLCCNV, and TbCSV from Assam which may open up a new insight into the understanding of DNA viruses infecting important crops of the state.