Resistance enhancement of transgenic tomato to bacterial pathogens by the heterologous expression of sweet pepper ferredoxin-I protein

Expression of a foreign gene to enhance plant disease resistance to bacterial pathogens is a favorable strategy. It has been demonstrated that expressing sweet pepper ferredoxin-I protein (PFLP) in transgenic plants can enhance disease resistance to bacterial pathogens that infect leaf tissue. In this study, PFLP was applied to protect tomato (Lycopersicon esculentum cv. cherry Clnl558a) from the root-infecting pathogen, Ralstonia solanacearum. Independent R. solanacearum resistant T-1 lines were selected and bred to produce homozygous T-2 generations. Selected T-2 transgenic lines 24-18-7 and 26-2-1a, which showed high expression levels of PFLP in root tissue, were resistant to disease caused by R. solanacearum. In contrast, the transgenic line 23-17-1b and nontransgenic tomato, which showed low expression levels of PFLP in root tissue, were not resistant to R. solanacearum? infection. The expansion of R. solanacearum populations in stem tissue of transgenic tomato line 24-18-7 was limited compared with the nontransgenic tomato Cln 1558a. Using a detached leaf assay, transgenic line 24-18-7 was also resistant to maceration caused by E. carotovora subsp. carotovora; however, resistance to E. carotovora subsp. carotovora was less apparent in transgenic lines 26-2-1a and 23-17-1b. These results demonstrate that PFLP is able to enhance disease resistance at different levels to bacterial pathogens in individual tissue of transgenic tomato.