Zhang Yuan-Chen, Cao Wen-Jie, Zhong Le-Rong, Godfray H Charles J, Liu Xiang-Dong
Department of Entomology, Nanjing Agricultural University, Nanjing, China.
Department of Zoology, University of Oxford, Oxford, United Kingdom.
Appl Environ Microbiol. 2016 Apr 4;82(8):2336-2346. doi: 10.1128/AEM.04131-15. Print 2016 Apr.
Buchnera aphidicolais an obligate endosymbiont that provides aphids with several essential nutrients. Though much is known about aphid-Buchnera interactions, the effect of the host plant on Buchnera population size remains unclear. Here we used quantitative PCR (qPCR) techniques to explore the effects of the host plant on Buchnera densities in the cotton-melon aphid, Aphis gossypii Buchneratiters were significantly higher in populations that had been reared on cucumber for over 10 years than in populations maintained on cotton for a similar length of time. Aphids collected in the wild from hibiscus and zucchini harbored more Buchnera symbionts than those collected from cucumber and cotton. The effect of aphid genotype on the population size of Buchnera depended on the host plant upon which they fed. When aphids from populations maintained on cucumber or cotton were transferred to novel host plants, host survival and Buchnera population size fluctuated markedly for the first two generations before becoming relatively stable in the third and later generations. Host plant extracts from cucumber, pumpkin, zucchini, and cowpea added to artificial diets led to a significant increase in Buchnera titers in the aphids from the population reared on cotton, while plant extracts from cotton and zucchini led to a decrease in Buchnera titers in the aphids reared on cucumber. Gossypol, a secondary metabolite from cotton, suppressed Buchnera populations in populations from both cotton and cucumber, while cucurbitacin from cucurbit plants led to higher densities. Together, the results suggest that host plants influence Buchnera population processes and that this may provide phenotypic plasticity in host plant use for clonal aphids.
蚜虫内共生菌是一种专性内共生菌，为蚜虫提供多种必需营养。尽管对蚜虫与蚜虫内共生菌的相互作用已有很多了解，但宿主植物对蚜虫内共生菌种群大小的影响仍不清楚。在这里，我们使用定量PCR（qPCR）技术来探究宿主植物对棉蚜体内蚜虫内共生菌密度的影响。在黄瓜上饲养超过10年的棉蚜种群中，蚜虫内共生菌的滴度显著高于在棉花上饲养相似时间的种群。从芙蓉和西葫芦上野生采集的蚜虫比从黄瓜和棉花上采集的蚜虫携带更多的蚜虫内共生菌共生体。蚜虫基因型对蚜虫内共生菌种群大小的影响取决于它们取食的宿主植物。当将在黄瓜或棉花上饲养的蚜虫种群转移到新的宿主植物上时，宿主的存活率和蚜虫内共生菌的种群大小在前两代中波动明显，在第三代及以后的世代中才变得相对稳定。添加到人工饲料中的黄瓜、南瓜、西葫芦和豇豆的宿主植物提取物导致在棉花上饲养的蚜虫种群中蚜虫内共生菌滴度显著增加，而棉花和西葫芦的植物提取物导致在黄瓜上饲养的蚜虫中蚜虫内共生菌滴度降低。棉酚是棉花中的一种次生代谢产物，抑制了来自棉花和黄瓜种群中的蚜虫内共生菌种群，而葫芦科植物中的葫芦素导致更高的密度。总之，结果表明宿主植物影响蚜虫内共生菌的种群过程，这可能为克隆蚜虫在宿主植物利用方面提供表型可塑性。
