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The concentration of nitrogen can generate different strategies in plants in response to stress. In this study, we investigated how nitrogen concentration interferes with the defense system of Annona emarginata . Low concentrations of nitrogen increased the allocation of photosynthetic resources to carbon metabolism, resulting in an increase in the synthesis of volatile substances involved in signaling and defense that contributed to antioxidant enzymes in overcoming stress. The availability of nitrogen at 5.62 mM concentration might have helped to induce increased resistance in the plants because at this concentration, signaling substances and defense substances (monoterpenes and sesquiterpenes) were observed. Plants cultivated with the highest nitrate concentration displaced energy for the reduction of this ion, likely forming nitric oxide, a signaling molecule. This condition, together with the decrease in carbon skeletons, may have contributed to the lower synthesis of volatile substances of the specialized metabolism that are also involved with signaling. Varying the nitrogen in Annona emarginata cultivation revealed that depending on the concentration, volatile substances show higher or lower synthesis and participation in the system of signaling and defense in the plant. These results may suggest that volatile substances participate in resistance to pests and diseases, which is a necessary condition for Annona emarginata to be preferentially used as rootstock for Annona x atemoya .

-The objective of this study was to characterize the chemical composition of the essential oil from the leaves of Annona emarginata (Schltdl.) H. Rainer 'terra-fria' and Annona squamosa L. The species were grown in a greenhouse for 18 months, which nutrient solution was applied weekly; the plants were then harvested and the leaves dried to extract the essential oil. The essential oil was analyzed by gas chromatography and mass spectrometry to study its chemical profiles. Eleven substances were found in the essential oil of A. emarginata, primarily (E)-caryophyllene (29.29%), (Z)-caryophyllene (16.86%), γ-muurolene (7.54%), α-pinene (13.86%), and tricyclene (10.04%). Ten substances were detected in the oil from A. squamosa, primarily (E)-caryophyllene (28.71%), (Z)-caryophyllene (14.46%), α-humulene (4.41%), camphene (18.10%), α-pinene (7.37%), β-pinene (8.71%), and longifolene (5.64%). Six substances were common to both species: (E)-caryophyllene, (Z)-caryophyllene, α-humulene, camphene, α-pinene, and β-pinene. Index terms: Annonaceae, secondary metabolites, terpenes, pharmacological potential. CARACTERIZAÇÃO DO PERFIL QUÍMICO DO ÓLEO ESSENCIAL DE Annona emarginata (Schltdl.) H. Rainer 'terra-fria'e Annona squamosa L.RESUMO-O objetivo do presente estudo foi caracterizar a composição química do óleo essencial das folhas de Annona emarginata (Schltdl.) H. Rainer 'terra-fria' e Annona squamosa L. As espécies foram cultivadas em casa de vegetação, com aplicação semanal de solução nutritiva até completar 18 meses, quando se realizaram a colheita e a secagem das folhas para a extração do óleo essencial, analisado por cromatografia gasosa acoplada à espectrometria de massas, para estudo dos perfis químicos. Onze substâncias majoritárias foram encontradas no óleo essencial de A. emarginata: (E)-cariofileno-29,29%; (Z)-cariofileno-16,86%; γ-muroleno-7,54%; α-pineno-13,86%; tricicleno-10,04%. No óleo de A. squamosa, 10 substâncias foram detectadas, entre elas: (E)-cariofileno-28.71%; (Z)-cariofileno-14,46%; α-humuleno-4,41%; canfeno-18,10%; α-pineno-7,37%, e β-pineno-8,71%; longifoleno-5,64%; majoritárias. (E)-cariofileno; (Z)-cariofileno; α-humuleno; canfeno; α-pineno, e β-pineno foram as seis substâncias comuns às duas espécies. Termos para indexação: Annonaceae, metabólitos secundários, terpenos, potencial farmacológico.

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