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第一作者:Hassan Salem
第一单位:美国埃默里大学
通讯作者:Hassan Salem
Abstract
背景回顾:Numerous adaptations are gained in light of a symbiotic lifestyle.
主要工作:Here, we investigated the obligate partnership between tortoise leaf beetles (Chrysomelidae: Cassidinae) and their pectinolytic Stammera symbionts to detail how changes to the bacterium’s streamlined metabolic range can shape the digestive physiology and ecological opportunity of its herbivorous host.
比较基因组-共性:Comparative genomics of 13 Stammera strains revealed high functional conservation, highlighted by the universal presence of polygalacturonase, a primary pectinase targeting nature’s most abundant pectic class, homogalacturonan (HG).
比较基因组-特性:Despite this conservation, we unexpectedly discovered a disparate distribution for rhamnogalacturonan lyase, a secondary pectinase hydrolyzing the pectic heteropolymer, rhamnogalacturonan I (RG-I).
试验:Consistent with the annotation of rhamnogalacturonan lyase in Stammera, cassidines are able to depolymerize RG-I relative to beetles whose symbionts lack the gene.
推测:Given the omnipresence of HG and RG-I in foliage, Stammera that encode pectinases targeting both substrates allow their hosts to overcome a greater diversity of plant cell wall polysaccharides and maximize access to the nutritionally rich cytosol. Possibly facilitated by their symbionts’ expanded digestive range, cassidines additionally endowed with rhamnogalacturonan lyase appear to utilize a broader diversity of angiosperms than those beetles whose symbionts solely supplement polygalacturonase.
结论:Our findings highlight how symbiont metabolic diversity, in concert with host adaptations, may serve as a potential source of evolutionary innovations for herbivorous lineages.
摘 要
共生的生活方式能够使得生物获得许多的适应性性状。本文中,作者研究了叶甲科龟甲亚科的龟叶甲虫与其能够分解果胶的共生菌Stammera之间的专性寄生关系,详细探究细菌精简的代谢谱如何影响其植食性寄主的消化生理和生态适应。对于13个Stammera菌株的比较基因组分析显示其功能比较保守,并且普遍都存在一个多聚半乳糖醛酸酶PG,是一个能够消化自然界中最丰富的果胶类物质,即同聚半乳糖醛酸HG的果胶酶。除了具有上述的保守性以外,作者还出乎意料地发现了鼠李聚糖半乳糖醛酸裂合酶的分散分布,该酶是一个能够水解果胶杂聚物鼠李聚糖半乳糖醛酸RG-I的果胶酶。与此结果一致,相比于那些体内共生菌缺少鼠李聚糖半乳糖醛酸裂合酶的甲虫而言,龟甲虫能够解聚RG-I。考虑到HG和RG-I遍布于植物的叶子中,因此体内含有靶向这两种多聚物的果胶酶的Stammera菌能够促使其植食性寄主克服植物细胞壁多糖的多样性,从而最大化其获取富含营养的胞质的能力。龟甲虫共生菌额外赋予的鼠李聚糖半乳糖醛酸裂合酶促进了其寄主取食范围的扩张,相比于那些含有只能提供多聚半乳糖醛酸酶的共生菌的甲虫而言,龟甲虫能够利用更加广泛的被子植物种类。本文的发现揭示了共生菌的代谢多样性与寄主的适应性相呼应,共同作用于植食性昆虫的演化创新。
通讯作者
**Hassan Salem**
个人简介:
1987年,马克斯-普朗克植物育种研究所,博士。
研究方向:植食性昆虫中共生菌的多样性。
doi: 10.1016/j.cub.2020.05.043
Journal: Current Biology
Published date: June 04, 2020
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