College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
PLoS Genet. 2019 Apr 24;15(4):e1008116. doi: 10.1371/journal.pgen.1008116. eCollection 2019 Apr.
Pythium guiyangense, an oomycete from a genus of mostly plant pathogens, is an effective biological control agent that has wide potential to manage diverse mosquitoes. However, its mosquito-killing mechanisms are almost unknown. In this study, we observed that P. guiyangense could utilize cuticle penetration and ingestion of mycelia into the digestive system to infect mosquito larvae. To explore pathogenic mechanisms, a high-quality genome sequence with 239 contigs and an N50 contig length of 1,009 kb was generated. The genome assembly is approximately 110 Mb, which is almost twice the size of other sequenced Pythium genomes. Further genome analysis suggests that P. guiyangense may arise from a hybridization of two related but distinct parental species. Phylogenetic analysis demonstrated that P. guiyangense likely evolved from common ancestors shared with plant pathogens. Comparative genome analysis coupled with transcriptome sequencing data suggested that P. guiyangense may employ multiple virulence mechanisms to infect mosquitoes, including secreted proteases and kazal-type protease inhibitors. It also shares intracellular Crinkler (CRN) effectors used by plant pathogenic oomycetes to facilitate the colonization of plant hosts. Our experimental evidence demonstrates that CRN effectors of P. guiyangense can be toxic to insect cells. The infection mechanisms and putative virulence effectors of P. guiyangense uncovered by this study provide the basis to develop improved mosquito control strategies. These data also provide useful knowledge on host adaptation and evolution of the entomopathogenic lifestyle within the oomycete lineage. A deeper understanding of the biology of P. guiyangense effectors might also be useful for management of other important agricultural pests.
贵阳腐霉，一种主要植物病原菌的卵菌，是一种有效的生物防治剂，具有广泛的潜力来管理各种蚊子。然而，其杀蚊机制几乎未知。在这项研究中，我们观察到贵阳腐霉可以利用角质层穿透和菌丝摄入消化系统来感染蚊子幼虫。为了探索致病机制，生成了一个具有 239 个 contigs 和 N50 contig 长度为 1009 kb 的高质量基因组序列。基因组组装约为 110 Mb，几乎是其他已测序的卵菌基因组的两倍。进一步的基因组分析表明，贵阳腐霉可能是由两个相关但不同的亲本物种杂交产生的。系统发育分析表明，贵阳腐霉可能与植物病原菌具有共同的祖先。比较基因组分析结合转录组测序数据表明，贵阳腐霉可能采用多种毒力机制感染蚊子，包括分泌蛋白酶和 kazal 型蛋白酶抑制剂。它还共享植物病原卵菌用于促进植物宿主定殖的细胞内 Crinkler (CRN)效应器。我们的实验证据表明，贵阳腐霉的 CRN 效应器对昆虫细胞有毒性。本研究揭示的贵阳腐霉感染机制和潜在的毒力效应器为开发改进的蚊子控制策略提供了基础。这些数据还为卵菌谱系中昆虫病原生活方式的宿主适应和进化提供了有用的知识。深入了解贵阳腐霉效应器的生物学特性可能对管理其他重要的农业害虫也有用。
