Analysing Brassica rapa genome by comparing natural accessions and the derivatives extracted from B. juncea allotetraploid

dc.contributor.advisorGurpreet Kaur
dc.contributor.authorSnehdeep Kaur
dc.date.accessioned2020-10-01T04:45:52Z
dc.date.available2020-10-01T04:45:52Z
dc.date.issued2020
dc.description.abstractPresent studies were conceived to undertake a comprehensive characterization of the phenotypic and molecular genetic diversities available in a large germplasm set comprising 195 fixed genotypes of Brassica rapa (AA; 2n=20). These included derived B. rapa lines extracted from B. juncea (AABB; 2n=36). DArTseq platform was used to sequence genomic DNA samples to aid SNP discovery. Field experiments were conducted during 2017-18 and 2018-19 over two sowing dates each at the forms of Punjab Agricultural University, Ludhiana. Morphological characterizations involved 18 traits representing flowering, crop architecture, yield components and seed quality. Molecular diversity analysis revealed that derived B. rapa clustered separately from the natural B. rapa. Natural B. rapa, itself formed two major groups with several subgroups representing variations among various subspecies of oleifera forms. Analysis of variance for phenotypic traits indicated significance of genotypic and genotype x environment interactions. Coefficient of variations was high for flowering, plant height, secondary branches and yield per plant. CV was lowest for pod length. Genome wide association studies were conducted using GAPIT 3 software. MLMM and Blink were preferred algorithms. We identified a large number of MTA’s involving target traits. Many of these were exclusive for DR. Annotation helped to predict candidate genes in the genomic region associated with the significant SNPs. Fifteen candidate genes were predicted for flowering traits. These genes are involved in the photoperiodic, gibberellic acid signaling pathways that control the expression of flowering genes. Several genes regulating flower development, maintenance of floral organ identity, regulation of timing of transition from vegetative to reproductive phase were also identified. For yield related traits we predicted genes involved in the growth and development, maintenance of shoot apical meristem, development of lateral organs, branching, auxin growth factors and leaf morphogenesis on A09. Two very important genes, IKU2 and LACS8 were identified for seed size. Candidate genes predicted for seed quality traits included genes involved in regulation of seed storage and reserves such as oil, protein and GSL. In conclusions, our studies have helped to catalogue molecular-genetic and phenotypic diversities present in B. rapa. These also established derived B. rapa as a genetic resource distinct from natural B. rapa. Many candidates were predicted for regulating key economic traits in the crop. Identified loci can be used in future marker-assisted selection (MAS) after due validation.en_US
dc.identifier.citationSnehdeep Kaur (2020). Analysing Brassica rapa genome by comparing natural accessions and the derivatives extracted from B. juncea allotetraploid (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.en_US
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810152178
dc.keywordsGenetic diversity, candidate genes, GWAS, flowering time, seed quality, derived B. rapaen_US
dc.language.isoenen_US
dc.pages106en_US
dc.publisherPunjab Agricultural University, Ludhianaen_US
dc.research.problemAnalysing Brassica rapa genome by comparing natural accessions and the derivatives extracted from B. juncea allotetraploiden_US
dc.subGenetics and Plant Breedingen_US
dc.subjectnullen_US
dc.themeAnalysing Brassica rapa genome by comparing natural accessions and the derivatives extracted from B. juncea allotetraploiden_US
dc.these.typePh.Den_US
dc.titleAnalysing Brassica rapa genome by comparing natural accessions and the derivatives extracted from B. juncea allotetraploiden_US
dc.typeThesisen_US
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