Seleção de compostos orgânicos voláteis com ação nematicida sobre Meloidogyne incógnita

Abstract

Plant parasitic nematodes are among the phytopathogens that cause the great damage to several economically important crops. Among these phytopathogens, Meloidogyne incognita stands out for being found all over the world and have a broad adaptation capacity to different agroecosystems. This species causes losses in many crops such as tomatoes, which is one of the economically important and most consumed crops. The main method of controlling M. incognita concerns the use of chemical nematicides which can present high toxicities to non-target organisms. Hence, there is an increasing demand for new products which may be satisfied with the use of volatile organic compounds (VOCs), which can be used as nematicides or as models for the development of new molecules more active against nematodes. Consequently, this work aimed to investigate in vitro and in vivo the nematicidal activity of 31 VOCs on M. incognita. In addition, was investigated in silico the most active VOC enzyme target in nematode. Among the studied VOCs (R)-carvone was most active, and was found that the lethal concentration for 50% (LC50) on second stage juveniles (J2) of M. incognita in vitro was 525 ± 20 µg/mL. Under the same conditions, the commercial nematicides carbofuran and fluensulfone showed LC50 equal to 171.5 ± 3.8 µg/mL and 34.3 ± 6.6 µg/mL, respectively. Moreover, the (R)-carvone was active against nematode eggs in vitro. When was used as a fumigant in experiment with substrate inoculated with nematode eggs, reduced by 100% the number of galls and eggs of nematodes in tomato plants grown on such substrate. Therefore, the in silico study resulted in acetylcholinesterase (AChE) as the target enzyme of (R)-carvone, which is an important enzyme to the nematode, acting on the hydrolysis of acetylcholine. Furthermore, was searched some chemical structures that should be more active in inhibiting the AChE enzyme than (R)-carvone, therefore three substances showed more affinities for the enzyme than (R)-carvine. In conclusion, (R)-carvone proved to be potentially useful for use as a fumigant nematicide and for use as a model in the development of chemical structures more active against the nematode, mainly by the use of acetylcholinesterase for the modeling of such chemical structures.