| The general goals of this dissertation are: (1) to quantify and qualify the glucosinolate phenotype variation among different crops and varieties of Brassica rapa, (2) to clone the major putative ortholog genes involving in the glucosinolate biosynthesis pathway in Brassica rapa, (3) to construct a cDNA-genomic DNA integrated linkage map, including the glucosinolate gene BrGSL-Elong, aligned to existing A genome maps and anchored to the Arabidopsis thaliana physical map.;Fourteen different glucosinolates were identified and quantified in the young leaves of 82 different varieties of Brassica rapa. Identification of accessions containing specific compounds and identification of accessions with highest and lowest content for each GSL compound in the survery, which will facilitate further genetic analysis for the synthesis of those compounds. In most varieties, gluconapin, glucobrassicanapin (aliphatic GSL), neoglucobrassicin, glucobrassicin (indolic GSL), and gluconaturtiin (aromatic GSL) are the five predominant glucosinolates. 2-Methyl-2-propenyl and n-Butyl GSL are not commonly found in Brassica rapa, their identities were confirmed by HPLC-MS. Most of the Chinese cabbages contain lower amount of aliphatic GSL than indolic GSL, whereas broccoleto, turnip and rapeseed all have much higher aliphatic GSL content than indolic GSL content.;The cloning of putative orthologs of five major genes, including BrGSL-Elong, BrGSL-Alk, Br-CYP83B1, Be-Sur1 and Br-St5a, involved in the Brassica rapa glucosinolate biosynthetic pathway could provide a useful base for further functional analysis of these genes and help to elucidate the glucosinolate biosynthesis pathway of B. rapa in the future. This is the first report on comparative gene organization and allelic variation for DNA sequences between the two cultivated Brassica species, B. rapa and B. oleracea , and one of the most extensive comparative reports between B. rapa to Arabidopsis.;An integrated transcriptome cDNA-genomic DNA map is constructed and aligned to existing A genome linkage groups and physical map of A. thaliana . This is the first transcriptome map constructed in B. rapa , which could serve as a frame work to add sequence-based additional markers for further comparative studies. This map contributes additional markers for more efficient marker assisted selection breeding schemes and map-based cloning of B. rapa genes. |
