Nanopartículas de Simonkolleite puras e dopadas com prata e cobre no controle de Xanthomonas spp. em tomateiro

Abstract

The tomato bacterial leaf spot, caused by four species of Xanthomonas spp. (X. vesicatoria, X. euvesicatoria, X. gardneri and X. perforans), is difficult to control due to the low effectiveness of the available products. Therefore, there is a need to seek effective and economically viable alternatives for the control of pathogens. Nanoparticles are molecules of nanometric size, which are easily attached to the bacterium's cell wall and reach the intracellular environment more effectively. The work aimed to evaluate pure and doped nanoparticles (NPs) of simonkolleite (SM) with silver (Ag) or copper (Cu), in concentrations of 0.1; 1; 5 and 10 wt%, in the control of Xanthomonas spp. in tomato. The toxicity of pure and doped simonkolleite nanoparticles was evaluated in the inhibition of bacterial growth in vitro, through the inhibition halo. The reduction in bacterial development was evaluated in relation to the contact time between nanoparticles and bacteria. In the treated seeds, the germination percentages and the detection of bacteria in the seeds were evaluated. Tomato plants inoculated with Xanthomonas spp. they were kept in a greenhouse and the severity of the disease was evaluated under preventive and curative treatment with pure NPs of SM and doped with 0.1Ag and 1 Cu. In vitro, NPs of SM: 5Ag performed better than the antibiotic cephalexin. In the time of 5 h of contact between nanoparticles and bacteria, the bacterial development decreased from 108 UFC.mL-1 to 120, 12 and 8 UFC.mL-1 in the treatments with pure SM NPS and doped with 0.1Ag and 1Cu, respectively. The germination test did not show differences between the germination percentage of the treated seeds and the control. In the greenhouse, at concentrations of 5 mg.mL-1, the performance of the doped SM NPs was equal to that of copper hydroxide in a preventive manner, and superior in curative treatment.