Lu Hong, Li Jing, Yang Pengcheng, Jiang Fei, Liu Hongran, Cui Feng
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China.
Front Microbiol. 2022 Mar 30;13:883436. doi: 10.3389/fmicb.2022.883436. eCollection 2022.
Host adaptation has the potential to cause rapid genetic variation in symbiotic microorganisms in insects. How mutations in symbiotic viruses favor viral fitness in hosts and even influence host adaptability to new environments remains elusive. Here, we explored the role of genetic divergence at one site of a symbiotic virus, virus (APV), in the host aphid's adaptation to unfavorable plants. Based on the transcriptomes of the pea aphid colony and colony, 46 single nucleotide polymorphism (SNP) sites were found in the APV genomes from the two aphid colonies. One SNP at site 5,990, G5990A, located at the RNA-dependent RNA polymerase (RdRp) domain, demonstrated a predominance from G to A when the host aphids were shifted from to the low-fitness plants or . This SNP resulted in a substitution from serine (S) to asparagine (N) at site 196 in RdRp. Although S196N was predicted to be located at a random coil far away from conserved functional motifs, the polymerase activity of the N196 type of RdRp was increased by 44.5% compared to that of the S196 type. The promoted enzymatic activity of RdRp was associated with a higher replication level of APV, which was beneficial for aphids as APV suppressed plant's resistance reactions toward aphids. The findings showed a novel case in which mutations selected in a symbiotic virus may confer a favor on the host as the host adapts to new environmental conditions.
宿主适应性有可能导致昆虫体内共生微生物发生快速的基因变异。共生病毒中的突变如何有利于病毒在宿主中的适应性，甚至影响宿主对新环境的适应性，目前仍不清楚。在此，我们探讨了一种共生病毒——蚜传病毒（APV）一个位点的遗传差异在宿主蚜虫适应不良植物过程中的作用。基于豌豆蚜品系和品系的转录组，在两个蚜虫品系的APV基因组中发现了46个单核苷酸多态性（SNP）位点。位于RNA依赖的RNA聚合酶（RdRp）结构域的第5990位的一个SNP，即G5990A，当宿主蚜虫从转移到低适应性植物或时，显示出从G到A的优势。这个SNP导致RdRp结构域第196位的丝氨酸（S）被天冬酰胺（N）取代。尽管预测S196N位于远离保守功能基序的无规卷曲处，但与S196型相比，N196型RdRp的聚合酶活性提高了44.5%。RdRp酶活性的提高与APV更高的复制水平相关，这对蚜虫是有益的，因为APV抑制了植物对蚜虫的抗性反应。这些发现展示了一个新的案例，即在共生病毒中选择的突变可能在宿主适应新环境条件时对宿主有利。
