Gomez-Polo Priscila, Ballinger Matthew J, Lalzar Maya, Malik Assaf, Ben-Dov Yair, Mozes-Daube Neta, Perlman Steve J, Iasur-Kruh Lilach, Chiel Elad
Department of Biology and Environment, University of Haifa - Oranim, Tivon, Israel.
Department of Biology, University of Victoria, Victoria, Canada.
Mol Ecol. 2017 Oct;26(20):5855-5868. doi: 10.1111/mec.14332. Epub 2017 Sep 14.
Hemipteran insects of the suborder Sternorrhyncha are plant sap feeders, where each family is obligately associated with a specific bacterial endosymbiont that produces essential nutrients lacking in the sap. Coccidae (soft scale insects) is the only major sternorrhynchan family in which obligate symbiont(s) have not been identified. We studied the microbiota in seven species from this family from Israel, Spain and Cyprus, by high-throughput sequencing of ribosomal genes, and found that no specific bacterium was prevalent and abundant in all the tested species. In contrast, an Ophiocordyceps-allied fungus sp.-a lineage widely known as entomopathogenic-was highly prevalent. All individuals of all the tested species carried this fungus. Phylogenetic analyses showed that the Ophiocordyceps-allied fungus from the coccids is closely related to fungi described from other hemipterans, and they appear to be monophyletic, although the phylogenies of the Ophiocordyceps-allied fungi and their hosts do not appear to be congruent. Microscopic observations show that the fungal cells are lemon-shaped, are distributed throughout the host's body and are present in the eggs, suggesting vertical transmission. Taken together, the results suggest that the Ophiocordyceps-allied fungus may be a primary symbiont of Coccidae-a major evolutionary shift from bacteria to fungi in the Sternorrhyncha, and an important example of fungal evolutionary lifestyle switch.
胸喙亚目半翅目昆虫以植物汁液为食，每个科都与一种特定的细菌内共生体有专性联系，这种细菌内共生体可产生汁液中缺乏的必需营养物质。蚧科（软蚧）是唯一尚未鉴定出专性共生体的主要胸喙亚目昆虫科。我们通过核糖体基因的高通量测序研究了来自以色列、西班牙和塞浦路斯的该科七个物种的微生物群，发现没有一种特定细菌在所有测试物种中普遍且大量存在。相反，一种与蛇形虫草相关的真菌——一个广为人知的昆虫病原谱系——高度普遍。所有测试物种的所有个体都携带这种真菌。系统发育分析表明，来自蚧科的与蛇形虫草相关的真菌与从其他半翅目昆虫中描述的真菌密切相关，尽管与蛇形虫草相关的真菌及其宿主的系统发育似乎不一致，但它们似乎是单系的。显微镜观察表明，真菌细胞呈柠檬形，分布于宿主全身，且存在于卵中，表明存在垂直传播。综上所述，结果表明与蛇形虫草相关的真菌可能是蚧科的主要共生体——这是胸喙亚目从细菌到真菌的一次重大进化转变，也是真菌进化生活方式转变的一个重要例子。
