Prospecção, conservação, caracterização genética, química, morfoagronômica e sazonalidade em germoplasma de Croton blanchetianus Baill

Abstract

Croton blanchetianus Baill. is a medicinal and aromatic species native to the Caatinga biome, widely distributed in the Brazilian Northeast. It is notable for its high bioactive and apicultural potential, and it is listed by the Ministry of Environment as a priority species for the region due to its potential economic importance. Nevertheless, its natural occurrence area is frequently reduced, primarily due to anthropogenic interventions. In view of the imminent threats to the species’ genetic variability, the Federal University of Sergipe (UFS) studied natural populations and subsequently established a collection of C. blanchetianus in its Active Germplasm Bank (AGB) for Medicinal and Aromatic Plants at UFS. This initiative allows the development of strategies for conservation and sustainable use of the species. The present research aims to evaluate the genetic and chemical diversity of natural populations of C. blanchetianus from municipalities in the state of Sergipe, as well as to establish a collection, characterize the accessions morpho-agronomically, chemically, and seasonally, and assess the antioxidant activity of the accessions conserved in the AGB. In the first article, the genetic diversity and structure of six natural populations of C. blanchetianus from different municipalities in the state were evaluated, using ISSR markers. Low genetic variability among populations (6%) was observed, and it was not possible to differentiate genotypes according to their geographic origin. In the second article, the chemical diversity of the essential oil from 70 genotypes of C. blanchetianus, collected from six natural populations in Sergipe, was evaluated. The major compounds found were α-pinene (1.60–13.37%), limonene (0.30–17.54%), β-phellandrene (4.38–16.04%), 1,8-cineole (0.16–13.56%), (E)-caryophyllene (0.31–13.14%), germacrene D (0.33–10.60%), bicyclogermacrene (5.06–27.47%), and spathulenol (4.34–29.83%), highlighting the broad chemical diversity of the species. In the third article, the morphoagronomic and chemical diversity of 26 C. blanchetianus accessions was characterized and analyzed. High variability among accessions was observed for all evaluated morpho-agronomic descriptors, particularly plant height (87.00–236.50 cm), crown diameter (48.75–131.00 cm), leaf area (74.50–176.37 cm²), dry mass (83.17–333.00 g/plant), and essential oil content (0.60– 1.60%). Chemically, the accessions were mostly comprised of α-pinene (3.90–12.02%), limonene (0.88–10.72%), β-phellandrene (1.30–17.51%), 1,8-cineole (0.36–11.57%), (E)- caryophyllene (1.82–12.48%), germacrene D (0.38–10.12%), bicyclogermacrene (8.37– 29.13%), and spathulenol (5.57–28.04%). In the fourth article, the chemical profile of the essential oil from leaves and fruits of five accessions of C. blanchetianus was analyzed, revealing quantitative and qualitative differences between plant organs. Leaves had a predominance of sesquiterpenes (37.34–62.03%), whereas fruits had higher levels of monoterpenes (23.97–61.03%). The exclusive presence of myrtenyl acetate in fruit essential oil indicates its potential as a chemical marker. In the fifth article, the seasonal influence (three harvest periods) on agronomic variables, chemical composition, and antioxidant activity of essential oil from 26 accessions of C. blanchetianus was evaluated. Accessions CBL-403 and CBL-503 showed the highest oil content (1.93%), while CBL-503 (17.41 g/plant) and CBL507 (17.38 g/plant) exhibited the highest essential oil yields. Sesquiterpenes predominated in harvests 1 and 2 (59.02% and 62.01%, respectively), while monoterpenes increased in harvest 3 (40.01%). A high antioxidant potential was observed in accession CBL-301 (DPPH: 66.24%; ABTS: 92.51%). These results indicate that C. blanchetianus exhibits exploitable genetic, morpho-agronomic, and chemical variability, and that its essential oils show seasonal plasticity and antioxidant activity.