A defining feature of the nutritional ecology of plant sap-feeding insects is that the dietary deficit of essential amino acids (EAAs) in plant sap is supplemented by EAA-provisioning microbial symbionts in the insect. Here, we demonstrated substantial variation in the nutritional phenotype of 208 genotypes of the pea aphid Acyrthosiphon pisum collected from a natural population. Specifically, the genotypes varied in performance (larval growth rates) on four test diets lacking the EAAs arginine, histidine and methionine or aromatic EAAs (phenylalanine and tryptophan), relative to the diet containing all EAAs. These data indicate that EAA supply from the symbiotic bacteria Buchnera can meet total aphid nutritional demand for only a subset of the EAA/aphid genotype combinations. We then correlated single nucleotide polymorphisms (SNPs) identified in the aphid and Buchnera genomes by reduced genome sequencing against aphid performance for each EAA deletion diet. This yielded significant associations between performance on the histidine-free diet and Buchnera SNPs, including metabolism genes predicted to influence histidine biosynthesis. Aphid genetic correlates of performance were obtained for all four deletion diets, with associations on the arginine-free diet and aromatic-free diets dominated by genes functioning in the regulation of metabolic and cellular processes. The specific aphid genes associated with performance on different EAA deletion diets are largely nonoverlapping, indicating some independence in the regulatory circuits determining aphid phenotype for the different EAAs. This study demonstrates how variation in the phenotype of associations collected from natural populations can be applied to elucidate the genetic basis of ecologically important traits in systems intractable to traditional forward/reverse genetic techniques.

中文翻译：

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豌豆蚜自然种群营养表型的宿主和共生体遗传决定因素。


以植物汁液为食的昆虫营养生态学的一个决定性特征是，植物汁液中必需氨基酸 (EAA) 的饮食不足由昆虫中提供 EAA 的微生物共生体来补充。在这里，我们证明了从自然种群中收集的豌豆蚜 Acyrthosiphon pisum 的 208 种基因型的营养表型存在显着差异。具体而言，相对于含有所有 EAA 的日粮，缺乏 EAA 精氨酸、组氨酸和蛋氨酸或芳香族 EAA（苯丙氨酸和色氨酸）的四种测试日粮的基因型表现（幼虫生长率）有所不同。这些数据表明，来自共生细菌 Buchnera 的 EAA 供应只能满足 EAA/蚜虫基因型组合的一部分的总蚜虫营养需求。然后，我们通过减少基因组测序与每种 EAA 缺失饮食的蚜虫表现，将在蚜虫和 Buchnera 基因组中发现的单核苷酸多态性 (SNP) 关联起来。这表明无组氨酸饮食的表现与 Buchnera SNP 之间存在显着关联，其中包括预测会影响组氨酸生物合成的代谢基因。所有四种缺失饮食都获得了蚜虫性能的遗传相关性，其中无精氨酸饮食和无芳香族饮食的关联主要由调节代谢和细胞过程的基因主导。与不同 EAA 缺失日粮表现相关的特定蚜虫基因在很大程度上不重叠，表明决定不同 EAA 的蚜虫表型的调节回路具有一定的独立性。 这项研究展示了如何应用从自然群体中收集的关联表型的变异来阐明传统正向/反向遗传技术难以处理的系统中生态重要性状的遗传基础。