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第一作者:Shaun P. Stice
第一单位:佐治亚大学
通讯作者:Brian H. Kvitko
Abstract
背景回顾-病原菌特性:Unlike most characterized bacterial plant pathogens, the broad-host-range plant pathogen Pantoea ananatis lacks both the virulence-associated type III and type II secretion systems.
背景回顾-病原菌+寄主:In the absence of these typical pathogenicity factors, P. ananatis induces necrotic symptoms and extensive cell death in onion tissue dependent on the HiVir proposed secondary metabolite synthesis gene cluster.
背景回顾-寄主特性:Onion (Allium. cepa L), garlic (A. sativumL.), and other members of the Allium genus produce volatile antimicrobial thiosulfinates upon cellular damage.
提出问题:However, the roles of endogenous thiosulfinate production in host-bacterial pathogen interactions have not been described.
主要发现:We found a strong correlation between the genetic requirements for P. ananatis to colonize necrotized onion tissue and its capacity for tolerance to the thiosulfinate“allicin” based on the presence of an eleven-gene, plasmid-borne, virulence cluster of sulfur redox genes.
研究结果:We have designated them “alt” genes for allicin tolerance. We show that allicin and onion thiosulfinates restrict bacterial growth with similar kinetics. The alt gene cluster is sufficient to confer allicin tolerance and protects the glutathione pool during allicin treatment. Independent alt genes make partial phenotypic contributions indicating that they function as a collective cohort to manage thiol stress.
结论:Our work implicates endogenous onion thiosulfinates produced during cellular damage as major mediators of interactions with bacteria.
展望:The P. ananatis-onion pathosystem can be modeled as a chemical arms race of pathogen attack, host chemical counterattack, and pathogen defense.
摘 要
与大多数的细菌性植物病原菌不同,具有广泛寄主范围的植物病原菌Pantoea ananatis同时缺少了与毒力相关的III型和II型分泌系统。在缺乏这些典型的治病因子情况下,P. Ananatis在洋葱组织中依赖于HiVir次生代谢产物合成基因簇来诱发坏死症状以及大规模的细胞死亡。洋葱和大蒜以及其它葱属的植物会在遭遇细胞损伤时产生挥发性的抑菌硫代亚磺酸盐。然而,内源的硫代亚磺酸盐在寄主与细菌性病原菌互作中的作用还不清楚。本文中,作者发现P. Ananatis能够侵染殖民洋葱坏死组织与其质体上所携带的11个具毒力的硫氧化还原基因簇所赋予的硫代亚磺酸盐大蒜素抗性存在很强的相关性。作者将其命名为alt基因,意指大蒜素抗性,即allicin tolerance。作者的研究显示大蒜素和洋葱硫代亚磺酸盐通过类似的特征限制细菌的生长。而alt基因簇足以赋予大蒜素抗性,并且在大蒜素处理时保护谷胱甘肽池。单独的alt基因会产生部分的表型,表明这些alt基因作为一个整体共同作用于硫醇胁迫。本文的研究揭示了细胞受损伤时所产生的内源性洋葱硫代亚磺酸盐是与细菌互作的主要介导因子。P. Ananatis与洋葱的病理系统可以作为一个模型系统用以研究病原菌攻击、寄主化学反击以及病原菌防御的化学军备竞赛。
通讯作者
**Brian H. Kvitko**
研究方向:
植物在遭遇细菌性病原菌时的免疫响应。
doi: 10.1016/j.cub.2020.05.092
Journal: Current Biology
Published date: July 02, 2020
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