Prospecção química de genótipos de milho com resistência à spodoptera frugiperda

Abstract

Maize (Zea mays L.) is used by the human being for ages, presenting great importance for the worldwide economy as one of the main food sources. The search of an increased productivity focus on the analysis and combat of the factors that contribute for the losses. Fall armyworm (Spodoptera frugiperda) is the main plague of maize production in the United States and Brazil, causing losses that can reach 37%. In this work, genotypes of maize with resistance to the worm were studied. The genotypes were cultivated and divided in two groups. One of them was used as a control and the other was infested with the fall armyworm.The extracts of the two groups of genotypes were prepared and their chromatographic profiles were taken by high-pressure liquid chromatography, being identified by comparison with a standard and, later, by mass spectrometry, as chlorogenic acid, described in literature as a substance with deterrent activity. The chromatograms obtained were classified using quimiometry methods like main component analysis and hierarchic analysis of groupings. After that, the activities of extracts were evaluated towards S. frugiperda and two phytopathogenic fungi. The majority of the genotypes presented reduction of chlorogenic acidcontents when they were infested by the insect. Moreover, some extracts of infested plants had presented good activity against the worm, indicating the synthesis of one or more bioactive substances. This alteration of the metabolic profile was perceived in the quimiometric analysis, where some pairs of infested-control genotypes had been presented distinct. The interaction between insect and the plant impacted in the metabolites production of the last group