Stress responses of tomato protoplasts to copper and paraquat

Abstract

Abbreviations used: HR, hypersensitivity response; MFI, mean fluorescence intensity; PCD, programmed cell death; ROS, reactive oxygen species. ABSTRACTPlants are often exposed to external biotic or abiotic agents that can damage cells. Biotic agents include molecules produced by pathogens, and abiotic agents include ultraviolet radiation, heavy metals and xenobiotic agents such as herbicides. Because of the importance of abiotic stresses and the limited knowledge of the defense responses of plants to stresses, a study was conducted using flow cytometry to evaluate endocellular events in protoplasts of two tomato species, Lycopersicon hirsutum and Lycopersicon esculentum, following exposure to 10 mM CuCl 2 and 1% paraquat. During the first 30 min of exposure to 10 mM CuCl 2, mean fluorescence intensity values in both species decreased by more than 50% compared to the untreated control. During the first 30 min of paraquat treatment, the production of reactive oxygen species, evaluated as the incidence of protoplasts in which the superoxide anion was present, was 32.9 % and 25.4%, respectively, for L. hirsutum and L. esculentum. Hyperpolarization of the mitochondria for both tomatoes species was observed during the first 2 h. The absence of early membrane damage and the markedly detrimental effects of the treatments on the mitochondria suggest that additional mechanisms which lead to cell death may be involved in these processes, and that these mechanisms may be associated with apoptosis. Key words: Lycopersicon, abiotic elicitation, apoptosis, programmed cell death. RESUMO Respostas dos protoplastos do tomate ao estresse gerado pelo cobre e o paraquatAs plantas estão expostas a agentes externos bióticos e abióticos que podem produzir dano nas celulas. Os agentes bióticos incluem moléculas produzidas por patógenos e os agentes abióticos incluem radiação ultravioleta, metais pesados e os agentes xenobióticos como os herbicidas. Devido à importancia do estresse abiotico e o limitado conhecimiento sob as respostas de defensa das plantas ao estresse, este estudo foi feito usando a citometría de fluxo para avaliar os eventos endocelulares de duas espécies de tomate: Lycopersicon hirsutum e Lycopersicon esculentum depois da exposição a 10 mM CuCl 2 e 1% do paraquat. Durante os primeiros 30 min da exposição ao CuCl 2 os valores da intensidade média da fluorescência em ambas as espécies diminuiu mais do 50% quando comparado com os controles não tratados. No caso do tratamento com o paraquat, depois dos primeiros 30 minutos a produção das espécies reativas do oxigênio, (avaliada pela presença do ânion superóxido) na espécie L. hirsutum e L. esculentum foi de 32,9% e 25,4%, respectivamente. A hiperpolarização das mitocôndrias das duas espécies do tomate foi observada durante as 2 primeiras horas. A ausência de dano no início ao nível da membrana e os efeitos adversos na mitocôndria causados pelos tratamentos sugerem que poda haver mecanismos adicionais que levam à morte celular, e que estes mecanismos podem estar associados ...

Protoplasts: a friendly tool to study aluminum toxicity and coffee cell viability

“…Encouraged by previous reports, we proposed the use of protoplasts (Poot-Poot and Hernandez-Sotomayor 2011 ; Rueda et al 2011 ; Panda and Matsumoto 2007 ; Marquès et al 2004 ; Davey et al 2005 ) as a practical model to study intimately the effect of metals such as Al on cellular processes. The aim of this work was to elucidate the mechanism by which aluminum confers toxic effects in crop plant cultures at the cellular level using isolated protoplasts from a C. arabica L. cell suspension; our research focused on nuclear interactions and DNA damage.…”