Kanvil S, Powell G, Turnbull C
Department of Life Sciences,Imperial College London,London SW7 2AZ,UK.
Bull Entomol Res. 2014 Dec;104(6):689-701. doi: 10.1017/S0007485314000443.
Aphid-plant interactions depend on genotypes of both organisms, which determine the two-way molecular exchange that leads to compatible or incompatible outcomes. The underlying genes are mostly unknown, making it difficult to predict likelihood of aphid success or host resistance, and hampering crop genetic improvement. Here we screened eight pea aphid clonal genotypes collected from diverse legume hosts, on a species-wide panel of Medicago truncatula (Mt) genotypes. Aphid virulence was measured by survival, fecundity and growth rate, together with scores for chlorosis and necrosis as host response indicators. Outcomes were highly dependent on the specific aphid-host genotype combinations. Only one Mt line was fully resistant against all clones. Aphid-induced host chlorosis and necrosis varied greatly, but correlated with resistance only in a few combinations. Bi-clustering analysis indicated that all aphid clones could be distinguished by their performance profiles across the host genotypes tested, with each clone being genetically differentiated and potentially representing a distinct biotype. Clones originating from Medicago sativa ranged from highly virulent to almost completely avirulent on both Medicago species, indicating that some were well adapted, whereas others were most likely migrants. Comparisons of closely related pairs of Australian Mt genotypes differing in aphid resistance revealed no enhanced resistance to European pea aphid clones. Based on the extensive variation in pea aphid adaptation even on unfamiliar hosts, most likely reflecting multiple biotype-specific gene-for-gene interactions, we conclude that robust defences require an arsenal of appropriate resistance genes.
蚜虫与植物的相互作用取决于这两种生物的基因型，这决定了导致相容或不相容结果的双向分子交换。其潜在基因大多未知，这使得预测蚜虫成功或宿主抗性的可能性变得困难，并阻碍了作物遗传改良。在此，我们在一个全物种范围的蒺藜苜蓿（Mt）基因型面板上，筛选了从不同豆科宿主收集的8种豌豆蚜克隆基因型。通过存活率、繁殖力和生长率来衡量蚜虫的毒力，同时将黄化和坏死评分作为宿主反应指标。结果高度依赖于特定的蚜虫 - 宿主基因型组合。只有一个Mt品系对所有克隆完全抗性。蚜虫诱导的宿主黄化和坏死差异很大，但仅在少数组合中与抗性相关。双聚类分析表明，所有蚜虫克隆都可以通过它们在测试的宿主基因型中的表现谱来区分，每个克隆在遗传上都是有差异的，并且可能代表一个独特的生物型。源自紫花苜蓿的克隆在两种苜蓿物种上的毒力从高到几乎完全无毒，这表明一些克隆适应性良好，而其他克隆很可能是迁移而来的。对在蚜虫抗性方面存在差异的澳大利亚Mt基因型的密切相关对进行比较，未发现对欧洲豌豆蚜克隆的抗性增强。基于豌豆蚜即使在不熟悉的宿主上也存在广泛的适应性差异，这很可能反映了多种生物型特异性的基因对基因相互作用，我们得出结论，强大的防御需要一系列合适的抗性基因。
