Submitted to: Biotechnology Letters
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/28/2005
Publication Date: 10/20/2005
Citation: Upchurch, R.G., Rose, M., Eweida, M., Zuo, W. 2005. Expression of the cercosporin transporter, cfp, in tobacco reduces frog-eye lesion size. Biotechnology Letters 27:1543-1550. Interpretive Summary: Cercospora fungi are plant pathogens that attack crop plants with the aid of a toxin they produce called cercosporin. In these fungi, a gene known as CFP provides self-resistance to cercosporin. CFP is a toxin pump that prevents the lethal accumulation of cercosporin within the fungal cell. We transferred the CFP pump gene into the model plant tobacco to determine if CFP could provide toxin and pathogen resistance to plants. Plants containing the CFP gene appeared normal in every way and set seed. We found that plants that accumulated the protein product of the CFP gene in their leaf cells were less susceptible to cercosporin and the Cercospora pathogen. Expression of the CFP gene in other crop plants that are susceptible to Cercospora may provide useful pathogen resistance.
Technical Abstract: The cercosporin Major Facilitator Superfamily MFS transporter CFP, under the control of the constitutive CaMV35S promoter, was introduced into Xanthi tobacco by Agrobacterium-mediated transformation. CFP transgenic plants were physically indistinguishable from non-transgenic Xanthi and progressed normally through the stages of tobacco growth to seed set. Accumulation of CFP protein in the leaf membrane fraction of transgenic plants was associated with reduced phytotoxicity to cercosporin and suppression of infection by Cercospora nicotianae conidia. Frog-eye leaf lesions on CFP transgenic plants were few in number and small, 1-3 mm, while lesions on non- transgenic Xanthi were up to ten-fold more numerous, larger, 6-8 mm, and spreading. We conclude that expression of CFP may have utility for disease control in other Cercospora-plant pathosystems where cercosporin is implicated in pathogen virulence.