Department of Crop Sciences, Agricultural Entomology, Georg-August University, Goettingen, Germany.
PLoS One. 2013;8(1):e54327. doi: 10.1371/journal.pone.0054327. Epub 2013 Jan 14.
Aphids feed on plant phloem sap, rich in sugars but poor in essential amino acids. However, sugars cause osmotic regulation problems for aphids, which they overcome by hydrolysing the sugars in their gut and polymerising the hydrolysis products into oligosaccharides, excreted with honeydew. Aphids harbour primary bacterial endosymbionts, which supply them with essential amino acids necessary for survival. They also harbour secondary (facultative) endosymbionts (sfS), some of which have a positive impact on life history traits, although it is not yet known whether they also play a role in providing effective tolerance to differing levels of water soluble carbohydrates (WSCs). We investigated the relationship between WSC content of cocksfoot cultivars and performance of clones of the English grain aphid Sitobion avenae F. We evaluated how clone genotype and their sfS modulate performance on these different cultivars. We therefore examined the performance of genetically defined clones of S. avenae, collected from different host plants, harbouring different sfS. The performance was tested on 10 Dactylis glomerata L. cultivars with varying WSC content. D. glomerata is known as a wild host plant for S. avenae and is also commercially planted. We found that high WSCs levels are responsible for the resistance of D. glomerata cultivars to specific S. avenae clones. The minimum level of WSCs conferring resistance to D. glomerata cultivars was 1.7% dw. Cultivars with a WSC content of 2.2% or higher were resistant to S. avenae and did not allow reproduction. Our results further indicate that sfS modulate to some extend host plant cultivar adaptation in S. avenae. This is the first study revealing the importance of WSCs for aphid performance. Cocksfoot cultivars with a high content of WSCs might be therefore considered for aphid control or used for resistance breeding in this and other grass species, including cereals.
蚜虫以植物韧皮部汁液为食，汁液富含糖分但缺乏必需氨基酸。然而，糖分会导致蚜虫渗透调节问题，它们通过在肠道中水解糖分并将水解产物聚合成长链寡糖，与蜜露一起排泄来克服这个问题。蚜虫体内携带有初级细菌内共生体，为它们提供生存所需的必需氨基酸。它们还携带有次级（兼性）内共生体（sfS），其中一些对生活史特征有积极影响，尽管尚不清楚它们是否也在提供对不同水平水溶性碳水化合物（WSCs）的有效耐受方面发挥作用。我们研究了饲用黑麦草品种中 WSC 含量与英国麦长管蚜克隆种群表现之间的关系。我们评估了克隆基因型及其 sfS 如何调节它们在这些不同品种上的表现。因此，我们研究了来自不同宿主植物、携带有不同 sfS 的 S. avenae 的遗传定义克隆的表现。我们在 10 个饲用黑麦草品种上进行了测试，这些品种的 WSC 含量不同。D. glomerata 是 S. avenae 的野生宿主植物，也有商业种植。我们发现，高 WSCs 水平是饲用黑麦草品种对特定 S. avenae 克隆抗性的原因。赋予对饲用黑麦草品种抗性的最低 WSCs 水平为 1.7% dw。WSC 含量为 2.2%或更高的品种对 S. avenae 具有抗性，不允许繁殖。我们的结果进一步表明，sfS 在一定程度上调节了 S. avenae 对宿主植物品种的适应。这是首次揭示 WSCs 对蚜虫表现重要性的研究。因此，饲用黑麦草品种中 WSCs 含量高的品种可能被考虑用于蚜虫防治或用于该品种和其他禾本科物种（包括谷类作物）的抗性育种。
