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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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20231
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Subject: Agricultural Biotechnology × Author: Dayma, Jyotsna × End date: 2023 × Start date: 2023 × Type: Thesis ×
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    ThesisItemOpen Access
    CLONING AND CHARACTERISATION OF cDNA ENCODING LEGUME SEED DEFENSIN AND ITS ACTIVITY AGAINST BRUCHIDS
    (2023) Dayma, Jyotsna; Acharjee, Sumita
    Defensins are small cysteine-rich peptides that play a crucial role in a plant’s innate immune system and are known for their well-established antimicrobial activity. However, their potential insecticidal properties have received limited exploration. Chen and his coworker have identified a defensin protein from mung bean (Vigna radiata) having insecticidal activity against bruchids. Our previous research confirmed the upregulation of a defensin gene in black gram due to the bruchid infestation. In the present study, sequencing of the full-length complementary DNA of the defensin gene from various legumes was performed. We found two amino acid sequence variants, PEP1 and PEP2 with 90 to 97% homology with the previously reported mung bean defensin protein, respectively. The PEP1 variant was found in black gram, pea, cowpea, and common bean, while PEP2 was found in mung bean, chickpea, and pigeon pea. The amino acid sequence alignment showed there are two amino acid substitutions in the signal peptide and three amino acid substitutions in mature protein regions of PEP1 compared to PEP2. Expression analysis of insecticidal defensin in different legumes revealed significant upregulation of the defensin gene in common beans, followed by black gram and cowpea, whereas, downregulation was observed in the case of pea, pigeon pea, mung bean, and chickpea that are susceptible to the bruchid infestation. The signal-truncated defensin protein was expressed in E. coli bacteria with an intein tag and a 32.5kD fusion protein was isolated. The cleavage of the tag through chitin affinity chromatography yielded mature peptides of 5.5 kD. Computational visualization showed that PEP1 displayed stronger interactions with the α-amylase enzyme of bruchids (Callosobruchus sp.), particularly through inter-chain hydrogen bonding when compared with PEP2. Moreover, PEP1 demonstrated higher (>14%) α-amylase inhibition activity compared to PEP2. In the insect bioassays, bruchids fed on PEP1 through an artificial diet at a concentration of 0.2% and 0.3% exhibited no adult emergence compared to PEP2. A plant expression vector was also constructed for expressing the defensin gene in the seeds of legumes. The results suggest the presence of amino acid substitutions in the defensin protein of legumes, which could be associated with the resistance to bruchid infestation. Thus, the expression of the black gram defensin gene regulated by a seed-specific promoter in grain legumes such as chickpea/ pigeon pea could provide durable resistance to bruchids.