Estudos metabolômicos associados a resistência de folhas de cajueiro (Anacardium Occidentale L.) à antracnose

Abstract

The cashew tree (Anacardium Occidentale L.) presents great economic importance to the Northeast of Brazil, mainly because of the use of its pseudocarp in the food industry and the commercialization of the cashew nuts in the world nut market. The technological evolution of the crop aimed to increase the productivity, however it has led to changes in the impact of some diseases, especially with the introduction of resistant plants. The Anthracnose caused by the fungus Colletotrichum gloeosporioides is the main disease that affects the cashew tree in Brazil and it is responsible for several production losses. The resistance of some clones of dwarf cashew has already been observed and described. However, the mechanism and/or the metabolites associated to this resistance have not been identified yet. Therefore, the present research has the purpose of developing a metabolomics study of four clones (CCP 76, BRS 226, BRS 189 and BRS 265) aiming to observe the secondary metabolism and, through chemometrics, identify the biomarkers responsible to the behavior of the plants against the attack by anthracnose. Ultrasonic assisted extraction was performed using an aqueous solution of 70% ethanol to extract the polar compounds of the leaves. The extracts obtained were analyzed in negative mode by UPLC-ESI-QTOF-MS(MS). The proposed method provided the putative identification of forty secondary metabolites. Principal Component Analysis (PCA) showed the separation of the samples into distinct groups indicating that the clones analyzed have different metabolic profiles. The Orthogonal Partial Least Squares - Discriminant Analysis (OPLS-DA) allowed the identification of flavonoids, mainly quercetin derivatives, and gallotannins as the biomarkers of the resistant plants.