Brassica is a very important vegetable group worldwide for which, biotic and abiotic stresses are major concern now a days. To address this concern, enhancement of resistance against stresses exploitation of stress resistance related genes, offers the most efficient approach. Among the stress resistance related genes, chitinase, defensin, Betv1 allergen family protein, longevity assurance gene, thaumatin-like genes etc. are playing vital roles for enhancement of resistance in Brassica. In this study, the above mentioned genes were selected from a gene ontology based EST analysis of the previously constructed full-length cDNA library of Brassica rapa cv. Osome and retrieved same family genes from the Brassica rapa database. The identified genes were then characterized through sequences analysis, comparison study and expression analysis after applying different biotic and abiotic stresses in B. rapa and B. oleracea. This study also characterized LIM genes, one cytoskeletal gene family, and
ix
investigated their relation with biotic and abiotic stresses. Seven chitinase and two LIM genes showed differential expressions in cabbage and chinese cabbage, respectively, after infection with Fusarium oxysporum f.sp. conglutinans. Alongside, three chitinase, four thaumatin-like, one defensin and one Betv1 pollen allergen family genes responded after Pectobacterium carotovorum subsp. carotovorum infection at certain time course in chinese cabbage. In addition, ten chitinase, seven thaumatin-like, one defensin and one BetV1 allergen family, one longevity assurance and ten LIM genes showed differential expression after abiotic stress treatments like, cold, salt, drought, abscisic acid (ABA) and pH stress for certain period in chinese cabbage. All these characterization and expression data revealed considerable number of potential genes those may be involved in resistance against biotic, abiotic and both stresses for Brassica. This kind of genomic study and identified potential genes would be very useful resource for molecular stress breeding of Brassica crops.