Identificação de genes-alvos na patogenicidade de Xanthomonas citri subsp. citri com enfoque no sistema de secreção tipo III
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Data
2016-08-25
Autores
Mendoza, Elkin Fernando Rodas [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Xanthomonas citri subsp. citri (Xac) é o agente causal do cancro cítrico, uma das principais doenças que acometem a citricultura mundial. Atualmente não há uma maneira eficiente de controle do cancro, e novos métodos devem ser desenvolvidos para o tratamento desta doença. Assim, o estudo dos mecanismos utilizados pela Xac durante o processo infeccioso pode revelar novos alvos para o desenvolvimento de compostos farmacológicos que possam eliminar ou controlar o patógeno. Neste estudo, a técnica de RNA-Seq foi utilizada para a identificação de genes diferencialmente expressos (GDE) na Xac em condições in vivo e in vitro. Para isso, cinco variedades de citros com níveis diferentes de suscetibilidade ao cancro cítrico, e meios de cultura indutores de fatores de virulência foram utilizados. Muitos dos genes que codificam para proteínas relacionadas ao sistema de secreção tipo 3 (T3SS), enzimas extracelulares, resposta ao estresse oxidativo, transportadores de ferro e fósforo foram induzidos pela Xac nas condições in vivo. No entanto, in vitro, os perfis de expressão para estes mesmos genes foram diferentes. Estes dados permitiram compreender melhor o ambiente intracelular do hospedeiro, e como este se relaciona com os mecanismos de ativação dos fatores de virulência e patogenicidade de Xac. Neste sentido, os dados apresentados neste estudo mostraram que o T3SS é o principal fator de virulência expresso por esta bactéria em condições in vivo. Além disso, nossos resultados sugerem também que as baixas concentrações de fósforo inorgânico (Pi) e nitrogênio que a bactéria percebe no apoplasto das plantas, são interpretadas como sinais para a ativação do T3SS. Mutações realizadas em genes relacionados com o transporte de Pi (∆phoR e ∆pstB) em Xac demostraram a perda de virulência por alteração na expressão dos genes do T3SS. Assim, estes dados demostram pela primeira vez em Xac um possível mecanismo de regulação entre o sistema de transporte de Pi e o T3SS. Este estudo revelou diferentes fatores de virulência e patogenicidade utilizados pela Xac para vencer as defesas da planta, o que permitirá levantar hipóteses sobre a identificação de possíveis alvos quimioterapêuticos para o tratamento do cancro.
Xanthomonas citri subsp. citri (Xac) is the causal agent of citrus canker, a major disease affecting citrus worldwide. Currently there is no effective way of cancer control, and new methods must be developed for the treatment of this disease. Thus, the study of the mechanisms used by Xac during the infectious process can reveal new targets for the development of pharmacologic compounds that can eliminate or control the pathogen. In this study, RNA-Seq technique was used to identify Xac differentially expressed genes (DEG) in vivo and in vitro conditions. For this purpose, five citrus varieties with different levels of susceptibility to citrus canker and culture mediums inducing virulence factors were used. Many of the genes encoding proteins of the type 3 protein secretion system (T3SS), extracellular enzymes, oxidative stress response, iron and phosphorus transport were induced in Xac in vivo conditions. However, the expression profiles for these same genes were different than observed in vitro conditions. These data allowed us to better understand the intracellular environment of the host, and how this relates to the activation mechanisms of pathogenicity and virulence factors in Xac. In this context, the data presented in this study show the T3SS as the main virulence factor expressed by the bacteria in vivo conditions. Furthermore, our results also suggest that low concentrations of inorganic phosphorus (Pi) and nitrogen, that bacteria sense in the plant apoplast, are interpreted as signals to activation of the T3SS. In this respect, mutations carried out in genes related to the transport of Pi (ΔphoR and ΔpstB) in Xac demonstrated loss of virulence by altering the expression of T3SS genes. Thus, these data identifies for the first time in Xac a possible regulatory mechanism between Pi transport system and T3SS. This study revealed different virulence and pathogenicity factors used by Xac to overcome the plant defenses. These discoveries allow raise hypotheses about the identification of potential chemotherapeutic targets to canker treatment.
Xanthomonas citri subsp. citri (Xac) is the causal agent of citrus canker, a major disease affecting citrus worldwide. Currently there is no effective way of cancer control, and new methods must be developed for the treatment of this disease. Thus, the study of the mechanisms used by Xac during the infectious process can reveal new targets for the development of pharmacologic compounds that can eliminate or control the pathogen. In this study, RNA-Seq technique was used to identify Xac differentially expressed genes (DEG) in vivo and in vitro conditions. For this purpose, five citrus varieties with different levels of susceptibility to citrus canker and culture mediums inducing virulence factors were used. Many of the genes encoding proteins of the type 3 protein secretion system (T3SS), extracellular enzymes, oxidative stress response, iron and phosphorus transport were induced in Xac in vivo conditions. However, the expression profiles for these same genes were different than observed in vitro conditions. These data allowed us to better understand the intracellular environment of the host, and how this relates to the activation mechanisms of pathogenicity and virulence factors in Xac. In this context, the data presented in this study show the T3SS as the main virulence factor expressed by the bacteria in vivo conditions. Furthermore, our results also suggest that low concentrations of inorganic phosphorus (Pi) and nitrogen, that bacteria sense in the plant apoplast, are interpreted as signals to activation of the T3SS. In this respect, mutations carried out in genes related to the transport of Pi (ΔphoR and ΔpstB) in Xac demonstrated loss of virulence by altering the expression of T3SS genes. Thus, these data identifies for the first time in Xac a possible regulatory mechanism between Pi transport system and T3SS. This study revealed different virulence and pathogenicity factors used by Xac to overcome the plant defenses. These discoveries allow raise hypotheses about the identification of potential chemotherapeutic targets to canker treatment.
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Palavras-chave
Transcriptoma, Mutagêneses, Interação planta-patógeno, RNA-seq, T3SS, Transcriptome, Mutagenesis, Plant-pathogen interaction, RNA-Seq, T3SS