Kim Minji, Lee Song Hee, Jeon Junhyun
Department of Biotechnology, College of Life and Applied Sciences, Yeungnam University, Gyeongsan, Gyeongbuk, Korea.
Plant Immunity Research Center, Seoul National University, Seoul, Korea.
Mycobiology. 2023 Sep 25;51(5):273-280. doi: 10.1080/12298093.2023.2257996. eCollection 2023.
The nucleolus is the largest, membrane-less organelle within the nucleus of eukaryotic cell that plays a critical role in rRNA transcription and assembly of ribosomes. Recently, the nucleolus has been shown to be implicated in an array of processes including the formation of signal recognition particles and response to cellular stress. Such diverse functions of nucleolus are mediated by nucleolar proteins. In this study, we characterized a gene coding a putative protein containing a nucleolar localization sequence (NoLS) in the rice blast fungus, . Phylogenetic and domain analysis suggested that the protein is orthologous to Rrp8 in . MoRRP8-GFP (translational fusion of MoRRP8 with green fluorescence protein) co-localizes with a nucleolar marker protein, MoNOP1 fused to red fluorescence protein (RFP), indicating that MoRRP8 is a nucleolar protein. Deletion of the gene caused a reduction in vegetative growth and impinged largely on asexual sporulation. Although the asexual spores of Δ were morphologically indistinguishable from those of wild-type, they showed delay in germination and reduction in appressorium formation. Our pathogenicity assay revealed that the is required for full virulence and growth within host plants. Taken together, these results suggest that nucleolar processes mediated by MoRRP8 is pivotal for fungal development and pathogenesis.
核仁是真核细胞细胞核内最大的无膜细胞器，在核糖体RNA（rRNA）转录和核糖体组装中起关键作用。最近研究表明，核仁还参与一系列过程，包括信号识别颗粒的形成以及对细胞应激的反应。核仁的这些多样功能是由核仁蛋白介导的。在本研究中，我们鉴定了水稻稻瘟病菌中一个编码假定蛋白的基因，该蛋白含有核仁定位序列（NoLS）。系统发育和结构域分析表明，该蛋白与酿酒酵母中的Rrp8是直系同源蛋白。稻瘟病菌RRP8（MoRRP8）与绿色荧光蛋白的翻译融合蛋白（MoRRP8-GFP）与红色荧光蛋白（RFP）融合的核仁标记蛋白MoNOP1共定位，表明MoRRP8是一种核仁蛋白。该基因的缺失导致了营养生长的减少，并在很大程度上影响了无性孢子形成。尽管ΔMoRRP8的无性孢子在形态上与野生型无异，但它们的萌发延迟且附着胞形成减少。我们的致病性分析表明，MoRRP8对于在宿主植物内的完全毒力和生长是必需的。综上所述，这些结果表明，由MoRRP8介导的核仁过程对于真菌发育和致病性至关重要。
