Bacterial wilt caused by Pseudomonas solanacearum is a serious plant disease in tropics and warm climate regions in the world. Agrobacterium mediated transformation was used for introduction of Xa21 gene for enhanced resistance to bacterial wilt in tomato cultivars. Factors effecting transformation such as pre-selection, preculturing of explants with acetosyringone had improved transformation efficiency. There are very few reports addressing the molecular mechanism of the plant responses to bacterial attack. Tomato cultivars were differentiated on the basis of their responses to bacterial wilt strain in to resistant and susceptible cultivars. Proteomic profiling was done for understanding of bacterial defenses. Molecular chaperones such as HSP70, 60 kDa chaperonin, protein disulfide isomerase & apical membrane antigen are speculated to have role in plant defenses against bacterial infection. Peroxiredoxin, ATP synthase, S-adenosyl methionine synthase, arginase and iron ABC transporter are other candidate proteins speculated for plant defense via JA and SA pathway.