Costs and benefits of a superinfection of facultative symbionts in aphids
Costs and benefits of a superinfection of facultative symbionts in aphids
复制标题
DOI：
10.1098/rspb.2005.3436
复制
发表时间：
2006-05-22
影响因子：
4.7
通讯作者：
Hunter, Martha S.
中科院分区：
文献类型：
--
作者：
Oliver, Kerry M.;Moran, Nancy A.;Hunter, Martha S.
动物与遗传微生物之间的共生关系在自然界广泛存在。在许多情况下，宿主可能被多个遗传共生体重复感染。豌豆蚜虫（豌豆蚜虫）除了专性初级共生体蚜虫（Buchnera aphidicola）外，还可能有一个以上的兼性共生体（称为次生共生体）。先前我们证明，在控制遗传背景下，感染共生沙雷氏菌或防御汉密尔顿氏菌（在该研究中称为R型和t型）的沙蚤对寄生蜂蚜虫的攻击更具抵抗力。在这里，我们研究了两种具有抗性的共生体同时感染的后果。我们发现，与共生葡萄球菌和防御葡萄球菌共感染的葡萄球菌系比单独感染的葡萄球菌系表现出更强的抗寄生能力。尽管这对抗性有额外的好处，但在我们对犹他州A. pisum共生体的调查中，共生S. symbiotica和防御H. defensa共生体的重复感染很少出现，这可能是由于严重的繁殖成本。定量聚合酶链反应估计表明，虽然防御丝杆线虫的密度在单一和重复感染的宿主中相似，但共生丝杆线虫的密度在重复感染的宿主中急剧增加。共生体的过度增殖或共生体之间的拮抗作用可能对蚜虫寄主有害。我们的研究结果表明，除了宿主-共生体的相互作用外，共生体本身的相互作用可能在决定自然种群中共生体的分布中起着关键作用。
Symbiotic associations between animals and inherited micro-organisms are widespread in nature. In many cases, hosts may be superinfected with multiple inherited symbionts. Acyrthosiphon pisum (the pea aphid) may harbour more than one facultative symbiont (called secondary symbionts) in addition to the obligate primary symbiont, Buchnera aphidicola. Previously we demonstrated that, in a controlled genetic background, A. pisum infected with either Serratia symbiotica or Hamiltonella defensa (called R- and T-type in that study) were more resistant to attack by the parasitoid Aphidius ervi. Here, we examined the consequences of A. pisum superinfected with both resistance-conferring symbionts. We found that an A. pisum line co-infected with both S. symbiotica and H. defensa symbionts exhibits even greater resistance to parasitism by A. ervi than either of the singly infected lines. Despite this added benefit to resistance, superinfections of S. symbiotica and H. defensa symbionts appeared rare in our survey of Utah A. pisum symbionts, which is probably attributable to severe fecundity costs. Quantitative polymerase chain reaction estimates indicate that while the density of H. defensa is similar in singly and superinfected hosts, S. symbiotica densities increased dramatically in superinfected hosts. Over-proliferation of symbionts or antagonistic interactions between symbionts may be harmful to the aphid host. Our results indicate that in addition to host-symbiont interactions, interactions among the symbionts themselves probably play a critical role in determining the distributions of symbionts in natural populations.