Abstract: Transepithelial electrical resistance-decreasing protein(TDP), produced as a recombinant protein(fTDP) in Escherichia coli, can induce resistance to tobacco mosaic virus(TMV) in tobacco. To improve its performance under field conditions, formulation carriers and additives were screened based on biocompatibility and formulation quality parameters. A 1% fTDP wettable powder(WP) with activity against TMV was subsequently developed, and its resistance-inducing efficacy was evaluated in greenhouse pot experiments and field trials. The optimized formulation comprised diatomite loaded with crude fTDP as the carrier(90%), sodium dodecylbenzenesulfonate as the wetting agent(5%), and methylene bis-methylnaphthalene sulfonate as the dispersant(5%). In greenhouse experiments, treatment with the 1% fTDP WP significantly reduced TMV accumulation in tobacco plants compared with the fTDP protein solution. The formulation also upregulated the transcription of the defense-related genes NPR1, PR1, PR1a, and PR1b, and enhanced the activities of defense enzymes, including superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT). In a 21-day field trial, the 1% fTDP WP achieved an average control efficacy of 49.6% against TMV, which was superior to unformulated fTDP(39.2%) and comparable to 8% ningnanmycin. These findings provide an experimental basis for the future optimization of protein elicitor formulations formulations and further investigation of field disease-resistance mechanism.

Key words: inducing disease resistance, tobacco mosaic virus, fTDP, wettable powder