Characterisation of the resistance derived from wild germplasm amphillo of Coffea arabica to Meloidogyne paranaensis and study of the enzymatic target of fluopyram in Meloidogyne spp.

Abstract

Meloidogyne paranaensis is one of the main nematode species that parasitize coffee and genetic control can be used as the main management strategy. Our aim with this study was to characterise the resistance of genotype 16-6-1, derived from germplasm Amphillo of Coffea arabica to M. paranaensis. Second stage juveniles (J2) penetrated the roots of genotype 16-6-1 in lower numbers and at a slower pace as compared to the susceptible cultivar Catuai Vermelho IAC 144. The strong blue fluorescence observed in the resistant, but not in the susceptible genotype, suggested that resistance responses occurred as early as 2 days after inoculation (DAI). Late responses involved the degradation of the giant cell at 14 DAI onwards in the resistant genotype, whereas nematode and giant cell development progressed normally in the susceptible cultivar. These results suggest that the resistance of the 16-6-1 genotype is related to early and late defense responses. The metabolic characterisation of the 16-6-1 genotype was also performed using the hydrogen nuclear magnetic resonance (1H NMR) technique. The main difference observed was the higher concentration of sucrose at 8 and 14 DAI in the 16-6-1 genotype, which suggests that sucrose is involved in the resistance of this genotype to M. paranaensis. Among the management strategies available for plant parasitic nematodes, chemical control stands out as an important tool due to its good efficiency. Fluopyram is a fungicide developed by Bayer Crop Science and acts against phytopathogenic fungi by inhibiting the enzyme succinate dehydrogenase. This molecule also has nematicidal action. The mechanism of action of this substance against plant parasitic nematodes is believed to be the same, but there is little evidence to support this information. In this study, the objective was to identify in silico the enzymatic target of fluopyram in Meloidogyne spp. The structures of fluopyram were designed using the ACD ChemSketch program. Later, these structures were submitted to conformational searches with the Open3Dalign software, and the more stable conformations were optimized using Mopac. Conformations with lower energies were submitted to pharmacophoric searches with the Lisica software, using the Ligand Expo database, to select protein ligands deposited in the RCSB Protein Data Bank. The enzyme 4L93 (heat shock protein 90 - HSP90) was selected as a possible target for fluopyram in Meloidogyne spp. Then, using the Autodock Vina program, a study of the interaction between fluopyram and the selected three-dimensional structures of the HSP90 enzyme was performed: 2JJC, 2QG0, 2VCI, 4FCP, 4L93. It was observed that the affinities of fluopyram for the enzymes were similar to the affinities of the inhibitors of this enzyme. Therefore, the results indicate that the enzymatic target of fluopyram in Meloidogyne spp. is the HSP90 enzyme.