Evolutionary divergence of the insect disease-encoding Serratia plasmid pADAP Supplementary Materials

Documents in support of statements made in the PhD thesis "Evolutionary divergence of the insect disease-encoding Serratia plasmid pADAP" by Thomas Lesley SitterAbstract for the thesisThe larvae of the New Zealand grass-grub (Costelytra givenii), cause significant damage to New Zealand’s pastures. Two diseases of grass-grub larvae, instigated by strains of Serratia entomophila and S. proteamaculans, have been identified and are being used as commercial biocontrol agents. The main virulence determinants of these Serratia strains, an Anti-feeding-prophage and an ABC-toxin-complex, are encoded on a 153-kb conjugative plasmid pADAP. Recently 75 Serratia strains with atypical disease phenology were sequenced with the goal of defining evolutionary points of divergent between plasmid variants and define potential co-evolution between plasmid and host. Phylogenetic analysis of the conserved plasmid “backbone”, residing between a conserved integrase (Int2) and the end of a conjugative pili cluster (PilL), revealed clustering of all the S. entomophila plasmids. Within the predicted backbone region, several intergenic replication and conjugation regions contained DNA inserts, one of which, positioned between TraG and TraC, demarcates chronic disease related plasmids from the non-chronic plasmids. These inserted regions were used as a marker to track the evolutionary divergence between the plasmids variants. A key finding was that all ABC-toxin-complex variants are co-located with a fimbria cluster, eluding to a role of fimbriae for the proper functionality of the ABC-toxin-complex. Keywords: Insecticidal activity, plasmids, evolutionary divergence, horizontal gene transfer, pan-genome, genome wide association study, grass grub, pADAP, Sep, Afp.

托马斯·莱斯利·西特（Thomas Lesley Sitter）博士论文《编码昆虫病害的沙雷氏菌（Serratia）质粒pADAP的进化分化》相关佐证文档。
本论文摘要：
新西兰草原蛴螬（Costelytra givenii）的幼虫会对新西兰的牧场造成严重危害。目前已发现两种由嗜虫沙雷氏菌（Serratia entomophila）和解淀粉沙雷氏菌（Serratia proteamaculans）菌株引发的草原蛴螬幼虫病害，这两种病害已被开发为商用生物防治制剂。上述沙雷氏菌菌株的主要毒力决定因子——抗采食前噬菌体（Anti-feeding-prophage）与ABC毒素复合物（ABC-toxin-complex）——均编码于一条153kb的接合性质粒pADAP之上。
近期，研究人员对75株表现出非典型病害表型的沙雷氏菌菌株完成测序，旨在明确质粒变体间的进化分歧节点，并解析质粒与宿主之间潜在的共进化关系。对位于保守整合酶（Int2）与接合菌毛簇（PilL）末端之间的质粒保守骨架进行系统发育分析，结果显示所有嗜虫沙雷氏菌的质粒均聚为一类。在预测的骨架区域内，多个基因间的复制与接合区域存在DNA插入片段，其中一段位于TraG与TraC之间的插入序列，可作为区分慢性病害相关质粒与非慢性质粒的标记。研究人员利用这些插入序列作为标记，追踪不同质粒变体间的进化分化过程。一项关键研究结果表明，所有ABC毒素复合物变体均与菌毛簇共定位，这暗示菌毛在ABC毒素复合物的正常功能发挥中具有重要作用。
关键词：杀虫活性、质粒、进化分化、水平基因转移、泛基因组、全基因组关联研究、草原蛴螬、pADAP、Sep、Afp