Análise da expressão gênica de Arabidopsis thaliana em resposta ao Citrus leprosis virus C e ao seu vetor Brevipalpus phoenicis

Abstract

Gene expression analysis of Arabidopsis thaliana in response to Citrus leprosis virus C and its vector Brevipalpus phoenicisCitrus leprosis, the main viral disease affecting citrus orchards in Brazil, is caused by Citrus leprosis virus C (CiLV-C, genus Cilevirus). CiLV-C has a bipartite genome of singled stranded positive RNA, which encodes six proteins. CiLV-C is plant-to-plant transmitted by Brevipalpus phoenicis mites and can infect more than 40 plant species, invariably producing localized chlorotic or necrotic lesions around the site of feeding of the viruliferous mites. Viral long distance movement in its hosts is not accomplished. To unveil the mechanisms determining the unique characteristic of the virus/mite/plant interaction, activities of main plant defense pathways were evaluated during aviruliferous and CiLV-C viruliferous mite infestation in Arabidopsis thaliana. The expression of 19 marker genes involved in defense responses along a time course experiment (6, 12 and 24 hours after infestation, and after appearance of leprosis symptoms) was assessed by RT-qPCR. Analyses showed that genes involved in the salicylic acid (SA) pathway were up-regulated during plant interaction with mite and virus. The SA pathway expression profile observed at the infestation by viruliferous mites resembled those observed for the aviruliferous mites, but plant response to both stimuli was stronger. Both the jasmonic acid and ethylene pathways were activated during mite/plant interaction and were repressed at the course of infection with CiLV-C, suggesting an antagonistic effect mediated by the activated SA pathway. Gene silencing mechanism was differentially regulated in response to both aviruliferous and viruliferous mites. Upon viral infection, plants responded with the activation of an AGO1-mediated first defense line, in early times of infection; and then switched to an AGO2-mediated defense. Results indicate the activation of a multifactorial process in response to CiLV-C and B. phoenicis mites in A. thaliana.

Leprose dos citros

“…yothersi, ainda amplamente desconhecidos. Dados prévios indicavam a indução de genes marcadores de vias hormonais em resposta a ambos ácaro e vírus em plantas de Arabidopsis (Arena, 2014). Para o estudo da interação planta/vírus, foram analisados: i) a presença de células mortas e espécies reativas de oxigênio (ROS) em ensaios histoquímicos, visando apoiar o envolvimento de uma resposta de hipersensibilidade (HR); ii) a cinética de acúmulo de CiLV-C ao longo da infecção através de RT-qPCR, para se identificar Os resultados obtidos permitiram a estruturação de um modelo da interação planta/patógeno/vetor (Fig 1).…”

“…yothersi, com o intuito de elucidar os mecanismos envolvidos no desenvolvimento da doença. Previamente, havia sido feita uma análise pontual da expressão de genes marcadores de vias de defesa em Arabidopsis infestadas com ácaros avirulíferos e virulíferos (Arena, 2014). Os dados obtidos foram complementados com ensaios histoquímicos de tecidos infectados, com a validação da expressão de genes selecionados em plantas de laranja-doce, e com análises da modulação do comportamento do ácaro vetor em plantas infectadas pelo CiLV-C, dando origem a um primeiro modelo da interação plantapatógeno-vetor (Capítulo 1, .…”