Resistência constitutiva a insetos ocasionada pelos acilaçucares e o efeito do silício no aumento da resistência e no desempenho agronômico no tomateiro.

Abstract

The tomato (Solanum lycopersicum) during its cultivation cycle presents serious phytosanitary problems due to its high susceptibility to pests, which increases the need to understand the defense compounds responsible for insect resistance in this crop. Silicon (Si) can enhance the constitutive defense of plants; however, studies with tomato plants are scarce, especially in genotypes with a high degree of constitutive resistance. Thus, this work aimed to study constitutive resistance to insects, the interaction of Si with constitutive resistance and productivity, and detect secondary defense metabolites in dwarf tomato plants of the UFU MC TOM 1 lineage. The Si content in the leaves and the constitutive resistance of the genotypes were also evaluated. To evaluate constitutive resistance and the relationship between Si and plant resistance, injuries caused to leaves by Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and to tomato fruits by Neoleucinodes elegantalis (Guennée) (Lepidoptera: Crambidae) were assessed. Under field conditions, four genotypes were evaluated: UFU MC TOM 1, Santa Clara (susceptibility pattern) and two hybrids LN4X2B3 and LN5X5B1, resulting from the crossing of normal-sized plants with UFU MC TOM 1 plants. For the detection of defense compounds, the metabolic profile of the UFU MC TOM 1 line was compared to that of a susceptible genotype (cv. Santa clara) through the metabolomic approach in plants produced in a greenhouse. Injuries caused by T. absoluta were lower in the UFU MC TOM 1 lineage, regardless of the application of Si to the soil, and there was no difference in injuries caused by this insect when comparing the other genotypes to each other. However, the injuries caused by the insect were lower in the hybrids LN5X5B1 and LN4X2B1 and in Santa Clara with the addition of Si. The percentage of fruits bored by N. elegantalis was three to eight times lower in UFU MC TOM 1 than in the other genotypes evaluated, which did not differ from each other, with or without the application of Si. The addition of Si to the soil reduced the symptoms of injuries caused by N. elegantalis in all tested genotypes. There was no effect of Si on the percentage of viable fruits or fruit production. The UFU MC TOM 1 lineage was more resistant to T. absoluta and N. elegantalis and had a higher acylsugar content than the other genotypes. There was no relationship between Si accumulation and constitutive resistance to pests in the tomato genotypes evaluated. The application of Si to the soil increased the acylsugar content in LN4X2B1 tomato leaves. Through metabolome analyses, it was possible to detect the substances riesling acetal, veranisatin C, PI-Cer(t18:0/22:0(2OH)) and tryptophan-glutamine-threonine, these were more expressed in UFU MC TOM 1 than in Santa Clara. Of these metabolites, veranisatin C has a neurotoxic effect on insects and mammals. The application of Si to the soil did not affect tomato production, regardless of the degree of constitutive resistance to pests of the genotypes, but increased resistance to T. absolute in susceptible genotypes and increased resistance to N. elegantalis in all genotypes, regardless of the degree of resistance, and can be considered a tool in the integrated management of tomato pests. The veranisatin C has the potential to explain the resistance of pests in the UFU MC TOM 1 lineage.