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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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20192
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Subject: Agricultural Biotechnology × Author: PARRAY, ROUF AHMAD × End date: 2021 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    GENETIC STUDIES FOR IMPROVING YIELD UNDER DROUGHT STRESS ENVIRONMENTS IN RICE OF ASSAM
    (2019-07) PARRAY, ROUF AHMAD; Baruah, Akhil Ranjan
    Drought is a major limiting factor for rice under rainfed ecosystem in Assam. In this context, thirteen rice cultivars with varied level of drought tolerance were chosen from a set of 272 different rice genotypes based on a field experiment conducted during 2014-15 season under drought. The thirty days old seedlings of 13 cultivars were tested for extensive morpho-physiological, biochemical parameters, relative transcript accumulation and global gene expression using next generation sequencing (NGS) method, and data were recorded at fifth, tenth and fifteenth day of withholding water (DWW) in order to obtain detail trait based gene architecture and to improve high yielding variety of Assam using transcript dynamics. Among the physiological traits studied, stomatal conductance decreased as the dehydration stress increased but the effect was minimum in Apo, Dumai and Tepi Dumai compared to others. Photosynthetic rate decreased with increasing water deficit, but the effect was less pronounced in Apo, Dumai and Tepi Dumai. The rate of transpiration decreased upto 5DWW but gradual increase was observed in later stage. Moreover, the fall in transpiration rate was less in Apo. Water use efficiency (WUE) of rice plants was enhanced significantly under moisture stress at all the three periods of stress (5DWW, 10DWW, 15DWW) in Apo, Tepi Dumai and Dumai. Reduction in RWC was experienced across all genotypes but the decrease was less prominent in Apo, Dumai and Tepi Dumai. Drought stress condition led to increased proline content across genotypes as compared to irrigated condition. Apo, Tepi Dumai, Dumai and Kali Murali showed rapid increase compared to others. Increase in root length was observed across all cultivars with Apo being the longest followed by Dumai and Ranjit. Then, five drought responsive pathway genes (OsDREB2, OsNAC1, bZIP16, OsbZIP 23, OsbZIP72) were chosen to check the differential expression patern in the cultivars at the same data point as mentioned above. Expression profiling of OsDREB2 showed significant increase in gene expression with increase in drought stress in the case of Apo and Dumai. Significant expression of the OsNAC1 was found in Apo, Dumai at different time points of dehydration stress whereas expression of ARC 10372 was prominent in 15DWW. Apo showed significant difference in expression of bZIP16 under all the three stages of water stress whereas Dumai and Ranjit showed enhanced expression compared to other cultivars. Expression profile of OsbZIP23 showed significant accumulation of transcripts in Apo in all stages followed by Dumai. Significant expression of OsbZIP72 was observed in Apo at 10DWW and 15DWW followed by Ranjit and Dumai. Based on the results of morpho-physiological, biochemical and expression analysis, three cultivars, viz., Ranjit, Apo and Dumai were chosen to study the detailed transcriptome at only 10DWW. Transcriptome profile revealed highest mapped genes in Dumai followed by Ranjit and Apo, however, only 14.5% genes were in common. Ranjit was found to be more responsive to abiotic stimulus including water stress. Gene ontology (GO) suggested no significant change of pathway genes upto 10 DWW among the three cultivars. The transcriptome data were validated using five differentially expressed genes in these three cultivars along with a F4 mapping population. It revealed similar trend, suggesting the present transcriptome data set was in good fit. However, detail transcriptome study in vital plant parts at different stages under drought stress will throw more light about the interaction of pathway genes to adress the problem better.
  • Thumbnail Image
    ThesisItemOpen Access
    GENETIC STUDIES FOR IMPROVING YIELD UNDER DROUGHT STRESS ENVIRONMENTS IN RICE OF ASSAM
    (AAU, Jorhat, 2019-07) PARRAY, ROUF AHMAD; Baruah, Akhil Ranjan
    Drought is a major limiting factor for rice under rainfed ecosystem in Assam. In this context, thirteen rice cultivars with varied level of drought tolerance were chosen from a set of 272 different rice genotypes based on a field experiment conducted during 2014-15 season under drought. The thirty days old seedlings of 13 cultivars were tested for extensive morpho-physiological, biochemical parameters, relative transcript accumulation and global gene expression using next generation sequencing (NGS) method, and data were recorded at fifth, tenth and fifteenth day of withholding water (DWW) in order to obtain detail trait based gene architecture and to improve high yielding variety of Assam using transcript dynamics. Among the physiological traits studied, Photosynthetic rate decreased with increasing water deficit, but the effect was less pronounced in Apo, Dumai and Tepi Dumai. The rate of transpiration decreased in all the cultivars under study. Moreover, the fall in transpiration rate was less in Apo. Water use efficiency (WUE) of rice plants was enhanced significantly under moisture stress at all the three periods of stress (5DWW, 10DWW, 15DWW) in Apo, Tepi Dumai and Dumai. Reduction in RWC was experienced across all genotypes but the decrease was less prominent in Apo, Dumai and Tepi Dumai. Drought stress condition led to increased proline content across genotypes as compared to irrigated condition. Apo, Tepi Dumai, Dumai and Kali Murali showed rapid increase compared to others. Increase in root length was observed across all cultivars with Apo being the longest followed by Dumai and Ranjit. Then, five drought responsive pathway genes (OsDREB2, OsNAC1, bZIP16, OsbZIP 23, OsbZIP72) were chosen to check the differential expression patern in the cultivars at the same data point as mentioned above. Expression profiling of OsDREB2 showed significant increase in gene expression with increase in drought stress in the case of Apo and Dumai. Significant expression of the OsNAC1 was found in Apo, Dumai at different time points of dehydration stress whereas expression of ARC 10372 was prominent in 15DWW. Apo showed significant difference in expression of bZIP16 under all the three stages of water stress whereas Dumai and Ranjit showed enhanced expression compared to other cultivars. Expression profile of OsbZIP23 showed significant accumulation of transcripts in Apo in all stages followed by Dumai. Significant expression of OsbZIP72 was observed in Apo at 10DWW and 15DWW followed by Ranjit and Dumai. Based on the results of morpho-physiological, biochemical and expression analysis, three cultivars, viz., Ranjit, Apo and Dumai were chosen to study the detailed transcriptome at only 10DWW. Transcriptome profile revealed highest mapped genes in Dumai followed by Ranjit and Apo, however, only 14.5% genes were in common. Ranjit was found to be more responsive to abiotic stimulus including water stress. Gene ontology (GO) suggested no significant change of pathway genes upto 10 DWW among the three cultivars. The transcriptome data were validated using five differentially expressed genes in these three cultivars along with a F4 mapping population. It revealed similar trend, suggesting the present transcriptome data set was in good fit. However, detail transcriptome study in vital plant parts at different stages under drought stress will throw more light about the interaction of pathway genes to adress the problem better.