Skaljac Marisa, Vogel Heiko, Wielsch Natalie, Mihajlovic Sanja, Vilcinskas Andreas
Branch for Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Giessen, Germany.
Entomology Department, Max Planck Institute for Chemical Ecology, Jena, Germany.
Front Physiol. 2019 Apr 17;10:438. doi: 10.3389/fphys.2019.00438. eCollection 2019.
Aphids are economically important pest insects that damage plants by phloem feeding and the transmission of plant viruses. Their ability to feed exclusively on nutritionally poor phloem sap is dependent on the obligatory symbiotic bacterium , but additional facultative symbionts may also be present, a common example of which is . Many species secrete extracellular enzymes, so we hypothesised that may produce proteases that help aphids to feed on plants. Molecular analysis, including fluorescence hybridization (FISH), revealed that colonises the gut, salivary glands and mouthparts (including the stylet) of the pea aphid , providing a mechanism to transfer the symbiont into host plants. was also detected in plant tissues wounded by the penetrating stylet and was transferred to naïve aphids feeding on plants containing this symbiont. The maintenance of by repeated transmission via plants may explain the high frequency of this symbiont in aphid populations. Proteomic analysis of the supernatant from a related but cultivable strain cultured in liquid medium revealed the presence of known and novel proteases including metalloproteases. The corresponding transcripts encoding these enzymes were detected in and in plants carrying the symbiont, although the mRNA was much more abundant in the aphids. Our data suggest that enzymes from may facilitate the digestion of plant proteins, thereby helping to suppress plant defense, and that the symbionts are important mediators of aphid-plant interactions.
蚜虫是具有重要经济意义的害虫，它们通过吸食韧皮部汁液和传播植物病毒来损害植物。它们仅以营养匮乏的韧皮部汁液为食的能力依赖于 obligatory 共生细菌，但也可能存在其他兼性共生体，其中一个常见的例子是 。许多 物种会分泌细胞外酶，因此我们推测 可能产生有助于蚜虫取食植物的蛋白酶。包括荧光 杂交（FISH）在内的分子分析表明， 定殖于豌豆蚜 的肠道、唾液腺和口器（包括口针）中，提供了一种将共生体转移到宿主植物中的机制。在被刺入的口针损伤的植物组织中也检测到了 ，并且它被转移到以含有这种共生体的植物为食的未感染蚜虫体内。通过植物反复传播来维持 可能解释了这种共生体在蚜虫种群中的高频率存在。对在液体培养基中培养的相关但可培养的 菌株的上清液进行蛋白质组分析，发现了包括金属蛋白酶在内的已知和新型蛋白酶。在 以及携带共生体的植物中检测到了编码这些 酶的相应转录本，尽管 mRNA 在蚜虫中更为丰富。我们的数据表明，来自 的酶可能有助于植物蛋白的消化，从而有助于抑制植物防御，并且这些共生体是蚜虫与植物相互作用的重要调节因子。
