RESUMO
Eucalyptus rust is caused by the biotrophic fungus, Austropuccinia psidii, which affects commercial plantations of Eucalyptus, a major raw material for the pulp and paper industry in Brazil. In this manuscript we aimed to uncover the molecular mechanisms involved in rust resistance and susceptibility in Eucalyptus grandis. Epifluorescence microscopy was used to follow the fungus development inside the leaves of two contrasting half-sibling genotypes (rust-resistance and rust-susceptible), and also determine the comparative time-course of changes in metabolites and proteins in plants inoculated with rust. Within 24 h of complete fungal invasion, the analysis of 709 metabolomic features showed the suppression of many metabolites 6 h after inoculation (hai) in the rust-resistant genotype, with responses being induced after 12 hai. In contrast, the rust-susceptible genotype displayed more induced metabolites from 0 to 18 hai time-points, but a strong suppression occurred at 24 hai. Multivariate analyses of genotypes and time points were used to select 16 differential metabolites mostly classified as phenylpropanoid-related compounds. Applying the Weighted Gene Co-Expression Network Analysis (WGCNA), rust-resistant and rust-susceptible genotypes had, respectively, 871 and 852 proteins grouped into 5 and 6 modules, of which 5 and 4 of them were significantly correlated to the selected metabolites. Functional analyses revealed roles for photosynthesis and oxidative-dependent responses leading to temporal activity of metabolites and related enzymes after 12 hai in rust-resistance; while the initial over-accumulation of those molecules and suppression of supporting mechanisms at 12 hai caused a lack of progressive metabolite-enzyme responses after 12 hai in rust-susceptible genotype. This study provides some insights on how E. grandis plants are functionally modulated to integrate secondary metabolites and related enzymes from phenylpropanoid pathway and lead to temporal divergences of resistance and susceptibility responses to rust.
RESUMO
Pyrostegia venusta is usually found in the secondary growth of the Atlantic forests, and in the Brazilian Savanna. Flowers and leaves of this plant are used in folk remedies for treating a wide variety of healthy conditions, this way is important evaluate its safety and antioxidant potential for this applications. For this, was made a ethanolic extract from its flowers and analyzed with toxicological,genotoxicity and antioxidant tests, the toxicological analysis was made by reproductive toxicity in rats and clatogenicity/aneugenicity in human lymphocytes. The genotoxicity was studied by micronucleus test mice bone marrow. The antimutagenic test in root cells of Allium cepa, the antioxidant assays used was DPPH, FRAP, Lipid Perxidation and REM, beyond of that the extract was analyzed in HPLC showing the profile of its compounds. The toxicological analysis showed that P. venusta has no negative significant effect on reproductive and cellular level. The micronucleus test in mouse bone marrow, the extract protected cells from cyclophosphamide, mutagenic compound, in a similar way. The A. cepa test showed that the extract reduced chromosomal disorders formations. The antioxidant activity of extract was significant, except in REM test. The phytochemical analysis showed the presence of flavonoids compounds. P. venusta extract does not present reproductive toxicity and genotoxic effects. However, the extract of this species showed antigenotoxic and antioxidant potential, possibly due to the different flavonoid compounds present in its extract.
Pyrostegia venusta é geralmente encontrada no crescimento secundário das florestas atlânticas e na savana brasileira. Flores e folhas desta planta são utilizadas em remédios populares para tratar uma grande variedade de doenças, desta forma é importante avaliar a segurança e o potencial antioxidante para estas aplicações. Para tanto, o extrato etanólico das flores foi avaliado com testes toxicológicos, genotóxicos e antioxidants. A análise toxicológica foi realizada por meio da toxicidade reprodutiva em ratos e a clatogenicidade/aneugenicidade em linfócitos humanos, a genotoxicidade foi estudada por teste de micronúcleo em medula óssea de camundongo. A antimutagenicidade em células da raiz de Allium cepa. Os ensaios antioxidantes utilizados foram DPPH, FRAP, TARBS e MRE. O extrato foi analisado em HPLC. A análise toxicológica reprodutiva mostrou que P. venusta não tem efeito negativo sobre o nível reprodutivo e cellular. No teste do micronúcleo o extrato protegeu as células da ciclofosfamida, um composto mutagênico. O teste de A. cepa mostrou que o extrato reduziu as formações dos distúrbios cromossômicos. A atividade antioxidante do extrato foi significativa, exceto no teste REM. A análise fitoquímica mostrou a presença de compostos flavonoídicos. O extrato de P. venusta não apresenta toxicidade reprodutiva e efeitos genotóxicos. No entanto, o extrato desta espécie apresentou potencial antigenotóxico e antioxidante, possivelmente devido aos diferentes compostos flavonoídicos presentes em seu extrato.
