Substitution of amino acid residues in the cytochrome b protein from Phytophthora infestans: functional implications and azoxystrobin sensitivity

• Ano de defesa: 2023
• Autor(a) principal: Alves, Gabriel
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Fitopatologia
• Palavras-chave em Português: Requeima - Aspectos moleculares - Modelos; Requeima - Controle; Produtos químicos agrícolas; Proteínas; Fitopatologia
• Link de acesso: https://locus.ufv.br//handle/123456789/32093; https://doi.org/10.47328/ufvbbt.2023.650

Late blight is caused by the oomycete Phytophthora infestans and is one of the main biotic factors that compromise yields of potato and tomato crops. Management of late blight is almost exclusively dependent on the application of oomicides. Azoxystrobin is a site-specific active ingredient that has "transkingdom" action, once it can be effective against fungal and oomycete plant pathogens. Unfortunately, reports of both fungal and oomycetes resistant to azoxystrobin are relatively common. Nevertheless, to date, there is no report of resistance in populations of P. infestans to azoxystrobin. The use of computational methods of molecular modeling applied to the study of proteins can help in the evaluation of the reasons why events of resistance to azoxystrobin have not been observed so far. For P. infestans, all positions in cytochrome b protein (cytB) that correspond to the loss of efficiency to azoxystrobin are set back one position in relation to the sequences of cytB of other microorganisms, with position 142 being the most important for the loss of efficiency of the molecule. The region around the site of interaction with the oomicide in P. infestans cytB is slightly variable, supporting less than 33% of the total number of possible substitutions. Position 142 can support a large number of residues without compromising stability, but which lead to resistance to azoxystrobin, which highlights the high risk of resistance events to this molecule. The non-occurrence of resistance to azoxystrobin in P. infestans seems to be related to a genomic factor that governs the stability of the cytochrome b gene sequence, since from the biophysical point of view there is no impediment to resistance to azoxystrobin. Such an approach may favor the understanding of the rules that govern the oomicide-protein molecular target interaction, serving as a theoretical subsidy for predicting the probability of loss of sensitivity in the plant pathogen population, as for other molecules that target the same protein. It is also expected that the adoption of this approach may help in the rational design of other oomicides and fungicides, and also control efficiency monitoring. Keywords: Molecular modeling. Oomicides. Protein diversity.