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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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20211
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Subject: Agricultural Biotechnology × Author: Deuri, Bharati × End date: 2021 × Start date: 2021 × Type: Thesis ×
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    ThesisItemOpen Access
    Optimization of in vitro transformation protocol and RNAi based gene silencing for viral (Cucumber Mosaic Virus) resistance in Bhut jolokia (Capsicum chinense Jacq.)
    (2021) Deuri, Bharati; Bhorali, Priyadarshini
    Bhut jolokia (Capsicum chinense Jacq.), one of the most popular and hottest chillies in the world, is widely cultivated in Assam and other North Eastern regions in India. A member of the Solanaceae family, Bhut jolokia is characterized by very high pungency due to the presence of high amount of phenolic alkaloid ‘Capsaicinoids’. It is an ideal chilli variety for extraction of oleoresin and capsaicin, which have high market demand due to their industrial uses and medicinal properties. Bhut jolokia production is challenged by several biotic constraints, particularly viral diseases, which affect its quality and yield. Among the viruses, Cucumber Mosaic Virus (CMV) causes severe crop damage, leading to low productivity. Current control measures for CMV are mainly preventive through vector management strategies, which are not adequate in controlling the disease. An effective way to control the disease is the use of biotechnological tools such as RNA interference (RNAi) technology to engineer resistance against the virus. Plants expressing a copy of a viral gene in sense and/or antisense orientation have shown resistance upon infection with the virus via post-transcriptional gene silencing. In the present investigation, an in vitro regenerationtransformation strategy has been optimized for Bhut jolokia and, a hairpin RNA (hpRNA) based gene silencing construct has been developed using the Replicase gene from CMV. The study was initiated by callus induction from Bhut jolokia leaf segments in MS basal medium. Very good quality callus were induced in MS medium supplemented with 0.5 mg/l or 1 mg/l 2,4-D. Multiple shoot induction and regeneration from callus were obtained in MS medium supplemented with 8.5 mg/l KIN and 0.5 mg/l TDZ along with 5 mg/l AgNO3 with maximum shoot initiation frequency of 95% and regeneration frequency of 90%. Root regeneration was found to be optimum in half strength MS medium supplemented with 1.5 mg/l NAA within 4 weeks of culture with maximum rooting frequency of 70%. For standardization of an Agrobacterium-mediated genetic transformation system, the strain LBA4404 carrying pCAMBIA1301 binary vector construct with gusA as the reporter gene and hptII and nptII as selection marker genes was used. Transformation was carried out using 45 days old callus and also with intact Bhut jolokia seeds as explants. Hygromycin concentration of 9 mg/l was found to be optimum for efficient selection of putative transformants. From a total of 30 nos. of callus infected by Agrobacterium, 9 numbers of putative transformed shoots were regenerated in presence of selection agent. Finally, only 2 (6.66%) fully rooted plants survived out of which, only 1 plant finally survived during hardening in the green house. Moreover, out of 30 nos. of infected seeds, a total of 7 numbers of putative transformed seedlings were developed. Finally, only 1 (3.33%) seedling survived, which was transferred to the green house for hardening. Thus, both callus and seeds could be used as explants for transformation in Bhut jolokia, although the frequency of putative transformants obtained using callus explants was higher than that in seed transformation. The putative transformants were confirmed by GUS histochemical assay and PCR analysis. For developing the RNAi construct, a 323 bp Replicase gene sequence was cloned into pHANNIBAL vector both in sense and anti-sense orientations. The construct was then transferred to pBI121 binary vector, which was electroporated into Agrobacterium strain LBA4404 for plant transformation. Functional validation of the CMV Replicase hp-RNA construct was done through bioassay in model plant Nicotiana benthamiana by Agro-infiltration. Transgene expression in N. benthamiana was confirmed by RT-PCR analysis. The bioassay results indicated suppression of CMV infection in Agro-infiltrated N. benthamiana plants when mechanically inoculated with CMV sap. Further, DAS-ELISA established the functional efficiency of the hpRNA construct in providing considerable level of resistance against CMV infection. The in vitro regeneration-transformation strategy and the hpRNA based gene silencing construct, developed through this study would serve as a foundation towards future studies on engineering resistance against CMV in Bhut jolokia.