AMARAVATHI, YAPARNA, ERAGAM2018-08-142018-08-142017http://krishikosh.egranth.ac.in/handle/1/5810064270D5522Drought is one of the major constraints in groundnut and governed by many genes with small effects operating in a coordinating manner. The present investigation was aimed for identification of differentially expressed transcripts in response to midseason drought in groundnut. To this end, a total of eleven genotypes viz., ICGV 07132, ICGV 07070, TCGS 1398, TCGS 1157, TCGS 1073, TCGS 1173, MLTG 4, Narayani, Tirupati 1, Kadiri 9 and Kadiri 6 were screened in pot culture for moisture stress tolerance. Among the eleven genotypes, TCGS 1157 and MLTG 4 genotypes showed early recovery after reaching the permanent wilting point and were grouped into moisture stress tolerant group. In contrast, Narayani and Kadiri 6 were highly sensitive to moisture stress. The field experiments were carried out at the research farm of Regional Agricultural Research Station (RARS) and molecular analysis at Genomics lab, Institute of Frontier Technology (IFT), RARS, Tirupati. The contrasting genotypes for mid-season drought viz., MLTG 4 and TCGS 1157 (tolerant) and Narayani and Kadiri 6 (susceptible) were further analyzed for morphological, physiological, biochemical and molecular parameters submitted to midseason moisture stress (50-80 DAS) in the field conditions. xiv SPAD Chlorophyll Meter Reading (SCMR) and Specific Leaf Area (SLA) were considered as surrogate traits for drought tolerance. The SPAD Chlorophyll Meter Reading values were increased as moisture stress period was increased upto 30 days in both drought tolerant and susceptible groundnut genotypes studied. SCMR can be used as non-destructive measure to estimate chlorophyll density while screening groundnut genotypes for drought tolerance. SLA decreased significantly in drought tolerant genotypes than in drought susceptible genotypes. Based on the SLA values, groundnut genotypes can be clearly distinguished from the drought susceptible genotypes. The increased levels of proline under drought stress can be better considered as drought stress indicator in groundnut. The accumulation of proline was more as the moisture stress progressed up to 30 days in all groundnut genotypes under the study. The total chlorophyll content under moisture stress imposed in groundnut genotypes initially was increased up to 70 DAS and declined at 80 DAS except for TCGS 1157. This was most probably due to prolonged vegetative growth phase in TCGS 1157 (120 days duration) when compared to MLTG 4, Narayani and Kadiri 6. To protect the cell from Reactive Oxygen Species generated in photorespiration, both catalase and peroxidase activities were increased in all the genotypes submitted to prolonged moisture stress. To unravel the molecular mechanisms conditioning drought tolerance, transcriptome was analyzed in groundnut subjected to mid-season stress (50-80DAS). To identify differentially expressed transcripts, cDNARAPD analysis was carried out using total RNA collected from leaves under well watered (control) and moisture stress situations at 10 (60 Days After Sowing), 20 (70 Days After Sowing) and 30 (Days After Sowing) days. Transcriptome was analyzed by cDNA-RAPD to identify differentially expressed transcripts in groundnut subjected to mid-season stress. cDNA-RAPD profiles with 35 RAPD markers resulted in a total of 823 reproducible differentially expressed transcripts in three regimes of moisture stresses. Among the 823 differentially expressed transcripts, 523 transcripts exhibited qualitative difference while 300 transcripts displayed quantitative differences in banding pattern of cDNA-RAPD profiles among all the four genotypes.en-USnullThesis