B. N. S., MURTHYB., TANUJA PRIYAS., JAGANNATHC., ASHWATHT. R., GURUPRASADPATIL, PRAKASHC., GOPALA KRISHNAN2021-01-012021-01-012016-06UHS13PGD73https://krishikosh.egranth.ac.in/handle/1/5810158053The pomegranate is cultivated since ancient times and believed to be native of Iran. It possesses various metabolites that made this crop commercially remunerative replacing subsistence farming status. However, the bacterial blight disease became a serious threat for its production in recent times. Hence, the present study was conducted at Indian Institute of Horticultural Research (IIHR), Bengaluru with a focus to identify the resistant lines and mine the genes that impart resistant reactions to facilitate breeding program. Cluster analysis classified 209 genotypes into 15 clusters with low intra-group and high intergroup similarities. Genotypes of cluster 15 possessing 108 B, 99 A, IC 318734, IIHR-30 and Daru-18 were found to confer resistance to bacterial blight incidence. The genotypes with varying degree of resistance exhibited significant variation at phenotypic and molecular level. The reactions against Xanthomonas axonopodis pv. punicae (Xap) for both highly susceptible (Ruby) and resistant (IC 318734) genotype were analyzed through physiological, biochemical and histological interventions to understand the defense mechanism. Transcriptome profiling of differentially expressed genes in resistant and susceptible genotypes through suppressive subtractive hybridization and Illumina HiSeq.TM500 (NGS) methods categorized all the genes into three groups viz., biological process, molecular function and cellular component. Subsequently, the genes identified were found confined to membrane transport, photosynthesis response, defense response, metabolic process and signal transduction sub groups. Further, genes specifically annotated to defense transcripts were catalase enzyme, transcription factors, LRR domain, trichome birefringence-like 34 and TMV resistance N-like in pomegranate with response to Xap. Thus, the investigation upshots would pave a path to identify disease resistant markers for effective crop improvement programme.EnglishThesis