Department of Genetics, Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany.
Department of Plant Physiology, Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Dornburger Str. 159, 07743 Jena, Germany.
Int J Mol Sci. 2021 Dec 18;22(24):13582. doi: 10.3390/ijms222413582.
Phytoplasmas are bacterial pathogens that live mainly in the phloem of their plant hosts. They dramatically manipulate plant development by secreting effector proteins that target developmental proteins of their hosts. Traditionally, the effects of individual effector proteins have been studied by ectopic overexpression using strong, ubiquitously active promoters in transgenic model plants. However, the impact of phytoplasma infection on the host plants depends on the intensity and timing of infection with respect to the developmental stage of the host. To facilitate investigations addressing the timing of effector protein activity, we have established chemical-inducible expression systems for the three most well-characterized phytoplasma effector proteins, SECRETED ASTER YELLOWS WITCHES' BROOM PROTEIN 11 (SAP11), SAP54 and TENGU in transgenic . We induced gene expression either continuously, or at germination stage, seedling stage, or flowering stage. mRNA expression was determined by quantitative reverse transcription PCR, protein accumulation by confocal laser scanning microscopy of GFP fusion proteins. Our data reveal tight regulation of effector gene expression and strong upregulation after induction. Phenotypic analyses showed differences in disease phenotypes depending on the timing of induction. Comparative phenotype analysis revealed so far unreported similarities in disease phenotypes, with all three effector proteins interfering with flower development and shoot branching, indicating a surprising functional redundancy of SAP54, SAP11 and TENGU. However, subtle but mechanistically important differences were also observed, especially affecting the branching pattern of the plants.
植原体是主要生活在其植物宿主韧皮部的细菌病原体。它们通过分泌靶向宿主发育蛋白的效应蛋白，剧烈地操纵植物发育。传统上，通过在转基因模式植物中使用强的、普遍活跃的启动子异位过表达来研究单个效应蛋白的作用。然而，植原体感染对宿主植物的影响取决于感染的强度和时间，以及与宿主发育阶段的关系。为了促进针对效应蛋白活性时间的研究，我们在. 中建立了三个最具特征的植原体效应蛋白 SECRETED ASTER YELLOWS WITCHES' BROOM PROTEIN 11 (SAP11)、SAP54 和 TENGU 的化学诱导表达系统。我们通过定量反转录 PCR 确定了 mRNA 表达，通过 GFP 融合蛋白的共焦激光扫描显微镜确定了蛋白积累。我们的数据揭示了效应基因表达的严格调控以及诱导后的强烈上调。表型分析表明，诱导时间的不同导致了疾病表型的差异。比较表型分析显示，迄今为止尚未报道过的疾病表型相似性，所有三种效应蛋白都干扰花发育和分枝，表明 SAP54、SAP11 和 TENGU 具有惊人的功能冗余。然而，也观察到了细微但机制上重要的差异，尤其是影响植物的分枝模式。
