Plant resistance against insects mainly depends on nutrient restriction and toxic metabolites, but the relative importance of nutrition and toxins remains elusive. We examined performance, nutrition ingestion, and transcriptome response of the English grain aphid, Sitobion avenae, feeding on resistant Xiaoyan 22 (XY22) and susceptible Xinong 979 (XN979) wheat cultivars. Aphids had lower body weight and fecundity when feeding on XY22 than on XN979, although the phloem sap of XY22 had a higher nutritive quality (in terms of amino acid:sucrose ratio). Aphids feeding on XY22 also had a lower honeydew excretion rate than those on XN979, suggesting that aphids ingested less phloem sap from XY22. The transcriptome data showed 600 differentially expressed genes (DEGs), and 11 of the top 20 KEGG pathways significantly enriched in DEGs were involved in nutrient metabolism. We found 81 DEGs associated with the metabolism of sugars, lipids, and amino acids, 59 of which were significantly downregulated in aphids feeding on XY22. In contrast, there were 18 DEGs related to detoxifying metabolism, namely eight UDP-glucuronosyltransferases, six cytochromes P450 monooxygenases, one glutathione S-transferase, two ATP-binding cassette transporters, and one major facilitator superfamily transporter; 12 of these were upregulated in the aphids feeding on XY22. Our results indicated that both the quantity and quality of phloem nutrition available to aphids are critical for the growth and development of aphids, and the higher resistance of XY22 is mainly due to the reduction in phloem sap ingested by aphids, rather than toxic metabolites.

植物对昆虫的抗性主要取决于营养限制和有毒代谢产物，但营养和毒素的相对重要性仍然难以捉摸。我们检查了英国谷物蚜虫（Sitobion avenae）的性能，营养摄入和转录组反应，以抗性小烟22（XY22）和易感的西农979（XN979）小麦品种为食。尽管XY22的韧皮部汁液具有较高的营养品质（就氨基酸：蔗糖比而言），但以XY22饲喂的蚜虫的体重和繁殖力比XN979低。饲喂XY22的蚜虫的蜜露排泄率也比XN979的蚜虫低，这表明蚜虫从XY22摄入的韧皮树液少。转录组数据显示600个差异表达基因（DEG），并且在DEG中显着富集的前20条KEGG途径中有11个参与营养物代谢。我们发现81个DEG与糖，脂质和氨基酸的代谢有关，其中59个在以XY22为食的蚜虫中显着下调。相比之下，有18个与解毒代谢相关的DEG，即8个UDP-葡萄糖醛酸转移酶，6种细胞色素P450单加氧酶，1种谷胱甘肽S-转移酶，2种ATP结合盒转运蛋白和1种主要的促进超家族转运蛋白；其中有12个在以XY22为食的蚜虫中上调。我们的结果表明，蚜虫可获得的韧皮部营养素的数量和质量对于蚜虫的生长和发育至关重要，而XY22的较高抗性主要是由于蚜虫摄入的韧皮部汁液而不是有毒代谢产物减少。