RESUMO
Natural and synthetic elicitors have contributed significantly to the study of plant immunity. Pathogen-derived proteins and carbohydrates that bind to immune receptors, allow the fine dissection of certain defence pathways. Lipids of a different nature that act as defence elicitors, have also been studied, but their specific effects have been less well characterized, and their receptors have not been identified. In animal cells, nanoliposomes of the synthetic cationic lipid 3-tetradecylamino-tert-butyl-N-tetradecylpropionamidine (diC14) activate the TLR4-dependent immune cascade. Here, we have investigated whether this lipid induces Arabidopsis defence responses. At the local level, diC14 activated early and late defence gene markers (FRK1, WRKY29, ICS1 and PR1), acting in a dose-dependent manner. This lipid induced the salicylic acid (SA)-dependent, but not jasmonic acid (JA)-dependent, pathway and protected plants against Pseudomonas syringae pv. tomato (Pst), but not Botrytis cinerea. diC14 was not toxic to plant or pathogen, and potentiated pathogen-induced callose deposition. At the systemic level, diC14 induced PR1 expression and conferred resistance against Pst. diC14-induced defence responses required the signalling protein EDS1, but not NDR1. Curiously, the lipid-induced defence gene expression was lower in the fls2/efr/cerk1 triple mutant, but still unchanged in the single mutants. The amidine headgroup and chain length were important for its activity. Given the robustness of the responses triggered by diC14, its specific action on a defence pathway and the requirement for well-known defence components, this synthetic lipid is emerging as a useful tool to investigate the initial events involved in plant innate immunity.
Assuntos
Amidinas/metabolismo , Arabidopsis/imunologia , Imunidade Vegetal , Arabidopsis/genética , Botrytis/imunologia , Cátions , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Pseudomonas syringae/imunologiaRESUMO
BACKGROUND: Botrytis cinerea is a phytopathogenic fungus responsible for the disease known as gray mold, which causes substantial losses of fruits at postharvest. This fungus is present often as latent infection and an apparently healthy fruit can deteriorate suddenly due to the development of this infection. For this reason, rapid and sensitive methods are necessary for its detection and quantification. This article describes the development of an indirect competitive enzyme-linked immunosorbent assay (ELISA) for quantification of B. cinerea in apple (Red Delicious), table grape (pink Moscatel), and pear (William's) tissues. RESULTS: The method was based in the competition for the binding site of monoclonal antibodies between B. cinerea antigens present in fruit tissues and B. cinerea purified antigens immobilized by a crosslinking agent onto the surface of the microtiter plates. The method was validated considering parameters such as selectivity, linearity, precision, accuracy and sensibility. The calculated detection limit was 0.97 µg mL-1 B. cinerea antigens. The immobilized antigen was perfectly stable for at least 4 months assuring the reproducibility of the assay. The fungus was detected and quantified in any of the fruits tested when the rot was not visible yet. Results were compared with a DNA quantification method and these studies showed good correlation. CONCLUSIONS: The developed method allowed detects the presence of B. cinerea in asymptomatic fruits and provides the advantages of low cost, easy operation, and short analysis time determination for its possible application in the phytosanitary programs of the fruit industry worldwide.
Assuntos
Botrytis/isolamento & purificação , Ensaio de Imunoadsorção Enzimática/métodos , Frutas/microbiologia , Antígenos de Bactérias/análise , Antígenos de Bactérias/imunologia , Botrytis/imunologia , Frutas/química , Malus/química , Malus/microbiologia , Doenças das Plantas/microbiologia , Pyrus/química , Pyrus/microbiologia , Vitis/química , Vitis/microbiologiaRESUMO
A wide range of plant species, including economically important crops such as vegetables, ornamentals, bulbs, and fundamentally fruits, can be affected by gray mold caused by the fungal pathogen Botrytis cinerea . This paper describes the development of a microfluidic immunosensor with micromagnetic beads (MMBs) coupled to carbon-based screen-printed electrodes (SPCEs) for the rapid and sensitive quantification of B. cinerea in apple (Red Delicious), table grape (pink Moscatel), and pear (William's) tissues. The detection of B. cinerea was carried out using a competitive immunoassay method based on the use of purified B. cinerea antigens immobilized on 3-aminopropyl-modified MMBs. The total assay time was 40 min, and the calculated detection limit was 0.008 µg mL(-1). Moreover, the intra- and interassay coefficients of variation were below 7%. The developed method allowed detects B. cinerea even in asymptomatic fruits and promises to be particularly useful for application in the agricultural industry.