RESUMEN
Abstract Succinate dehydrogenase inhibitors (SDHIs), fungicides currently most used in agriculture in Brazil, act by blocking the enzyme succinate dehydrogenase (SDH) from plant pathogens. However, studies show that SDHIs can not only inhibit SDH activity in target fungi, but also block that activity in human cells. Considering the medical and agricultural implications of SDH, the purpose of this narrative review is to describe the relationship between exposure to fungicides SDHIs and epigenetic regulation of SDH associated with the development of gastrointestinal stromal tumor, pheochromocytoma/paraganglioma, and cancer. The results obtained with the research showed that the human SDH enzyme exhibited sensitivity to some tested SDHIs, which may cause microcephaly and defects in neurological development. Deficiency of SDH activity causes accumulation of succinate which can act as an oncometabolite inhibit-ing iron-dependent dioxygenases and alpha-ketoglutarate, eleven translocation -TET and histone demethylases, inducing epigenetic changes that lead to multiple cancers and other diseases. Therefore, further in vitro and in vivo analyzes should be performed to assess susceptibility to diseases influenced by the toxic effect of SDHIs.
Resumo Os inibidores da succinato desidrogenase (SDHIs), fungicidas atualmente mais utilizados na agricultura no Brasil, atuam bloqueando a enzima succinato desidrogenase (SDH) de fitopatógenos. No entanto, estudos mostram que SDHIs podem nao apenas inibir a atividade de SDH em fungos alvo, mas também bloquear essa atividade em células humanas. Considerando as implicares médicas e agrícolas do SDH, o objetivo desta revisao narrativa é descrever a relaqao entre a exposiqao a fungicidas SDHIs e a regulaqao epigenética do SDH associada ao desenvolvimento de tumor estromal gastrointestinal, feocromocitoma/paraganglioma e cáncer. Os resultados obtidos com a pesquisa mostraram que a enzima SDH humana apresentou sensibilidade a alguns SDHIs testados, que podem causar microcefalia e defeitos no desenvolvimento neurológico. A deficiencia da atividade da SDH causa acumulo de succinato que pode atuar como um oncometabólito inibindo as dioxigenases dependentes de ferro e alfa-cetoglutarato, onze translocaqóes -TET e histonas desmetilases, induzindo alteraqóes epigenéticas que levam a múltiplos canceres e outras doenqas. Portanto, análises adicionais in vitro e in vivo devem ser realizadas para avaliar a suscetibilidade a doenqas influenciadas pelo efeito tóxico dos SDHIs.
Resumen Los inhibidores de la succinato deshidrogenasa (SDHI), los fungicidas actualmente más utilizados en la agricultura en Brasil, actúan bloqueando la enzima succinato deshidrogenasa (SDH) de los patógenos de las plantas. Sin embargo, los estudios muestran que los SDHI no solo pueden inhibir la actividad de SDH en los hongos objetivo, sino que también bloquean esa actividad en las células humanas. Teniendo en cuenta las implicaciones médicas y agrícolas de SDH, el propósito de esta revisión narrativa es describir la relación entre la exposición a fungicidas SDHI y la regulación epigenética de SDH asociada con el desarrollo de tumores del estro-ma gastrointestinal, feocromocitoma/paraganglioma y cáncer. Los resultados obtenidos con la investigación mostraron que la enzima SDH humana mostró sensibilidad a algunos SDHI probados, lo que puede causar microcefalia y defectos en el desarrollo neurológico. La deficiencia de la actividad de SDH provoca la acumulación de succinato que puede actuar como un oncometabolito que inhibe las dioxigenasas dependientes de hierro y el alfa-cetoglutarato, once translocaciones -TET e histona desmetilasas, induciendo cambios epigenéticos que conducen a múltiples cánceres y otras enfermedades. Por lo tanto, se deben realizar más análisis in vitro e in vivo para evaluar la susceptibilidad a enfermedades influenciadas por el efecto tóxico de los SDHI.
RESUMEN
Studies show that DNA methylation is associated with plant immunity but little is known as to how this epigenetic mechanism assists plants in adjusting their responses to biotic stress, especially when interacting with an hemibiotrophic pathogen such as citrus Phytophthora. The aim of the present study was to assess the effects of scion-rootstock interaction on plant resistance to P. citrophthora infection and DNA methylation patterns in 'Pera' sweet orange and 'Tahiti' acid lime grafted onto 'Rangpur' lime and 'Tropical' sunki rootstocks reinoculated with P. citrophthora. Results showed that reinoculated plants of the 'Pera' sweet orange/'Rangpur' lime and 'Tahiti' acid lime/'Tropical' sunki combinations with more and less sensitive varieties to Phytophthora, presented smaller stem lesions and increased frequency of full methylation and hemimethylation rates, compared to inoculated plants. In contrast, 'Tahiti' acid lime/'Rangpur' lime, two highly sensitive varieties, and 'Pera'/'Tropical' sunki, two much less sensitive varieties, showed high increases in the frequency of hemimethylation and non-methylation levels. Results suggest that in citrus, both the scion-rootstock interaction and DNA methylation affect the response to P. citrophthora infection. Reinoculated plants, depending on the combination, showed changes in intracellular hyphae growth through the formation of sets of fibers and crystal accumulation in the periderm, cortex, and phloem. In addition, starch grain concentration was higher in reinoculated plants in comparison to inoculated plants. These findings support the assumption that DNA methylation is a plant defense mechanism and therefore may be exploited to improve the response of plants to the gummosis of P. citrophthora in citrus.