Abstract
Co-infection of maize chlorotic mottle virus (MCMV) with a virus in the Potyviridae family, such as sugarcane mosaic virus, usually leads to maize lethal necrosis (MLN). Over the past decade, MCMV/MLN has emerged in many countries/regions of the world and resulted in serious yield loss in maize production. Although partial functions of some MCMV-encoded proteins have been identified, the host factors related to MCMV replication are poorly understood. Here, we show that maize peroxisomes can form aggregated bodies in MCMV-infected leaf cells. The dsRNA binding-dependent fluorescence complementation assay indicated that the aggregated peroxisomes in maize served as the major replication site of MCMV. In addition, our results revealed that all the three maize catalases were present mostly in peroxisomes in the presence or absence of MCMV. Furthermore, we determined that inhibition of catalase activity or induction of reactive oxygen species (ROS) in maize protoplasts significantly reduced the accumulation of MCMV RNA. In summary, this research reveals the replication site of MCMV and an important role of maize catalases in supporting virus replication. Our results are conducive to understanding the pathogenesis of MCMV and identifying targets for resistance breeding or gene regulation strategies.
Highlights
Pathogenic infections in plants are frequently associated with the accumulation of reactive oxygen species (ROS), such as superoxide anion radical (.O2−), hydroxyl radical (.Hydroxyl radical (OH)) and hydrogen peroxide (H2O2), which serve as signal transduction molecules to control a large array of biological processes, including senescence, growth and development, and biotic or abiotic stress responses (Schippers et al 2012; Lehmann et al 2015; Guo et al 2017; Zhou et al 2018)
maize chlorotic mottle virus (MCMV) infection induces the formation of aggregated bodies of peroxisomes in maize leaves Here, 8-day-old maize seedlings (B73) inoculated with MCMV showed chlorotic, mottle symptoms and even necrosis at 10 days post-inoculation, whereas no symptom was observed in control plants mock-inoculated with phosphate buffer (Fig. 1b, c)
Red fluorescence from DsRed-SKL was redistributed to aggregated bodies in MCMV-infected maize leaves (Fig. 2b), while the fluorescence for DsRed alone was unchanged after MCMV infection (Fig. 2b)
Summary
Pathogenic infections in plants are frequently associated with the accumulation of reactive oxygen species (ROS), such as superoxide anion radical (.O2−), hydroxyl radical (.OH) and hydrogen peroxide (H2O2), which serve as signal transduction molecules to control a large array of biological processes, including senescence, growth and development, and biotic or abiotic stress responses (Schippers et al 2012; Lehmann et al 2015; Guo et al 2017; Zhou et al 2018). The generation of ROS, known as the oxidative burst, is considered the earliest response of plant cells to biotic. Among the H2O2-scavenging enzymes, catalase (CAT) is a highly conserved enzyme that catalyzes the decomposition of hydrogen peroxide (H2O2) to produce water and oxygen and plays a critical role in plant disease resistance. Catalase is a tetrameric enzyme consisting of polypeptides of 50–70 kDa (Mhamdi et al 2010)
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