Evolution of xylophagy in longhorned beetles: Diversity, evolutionary history and functional characterization of plant cell wall degrading enzymes in beetles of the family Cerambycidae

有魅力的长角甲虫（鞘翅目：天牛科）是地球上最多样化的食木动物群体的一部分。这些甲虫的幼虫已经进化到在一个极具挑战性和次优的环境中茁壮成长-木材材料-在那里它们必须科普植物细胞壁的结构多糖，这些多糖是它们的大部分食物。早期的研究表明，天牛幼虫通过产生植物细胞壁降解酶（PCWDEs）分解纤维素、半纤维素和果胶，而不依赖于共生体。然而，在这群甲虫中，相应的基因和它们的进化方式仍然难以捉摸。本研究旨在通过RNA-Seq技术对甲虫中肠转录组序列进行分析，并结合系统发育分析和异源表达系统中酶活性的快速筛选，对天牛科昆虫中PCWDEs基因进行鉴定和特征分析，以确定其进化历史。这项研究将提供信息，说明在天牛科进化过程中，宿主植物和取食行为如何塑造这些基因家族的组成;以及多氯WDEs如何有助于建立和维持这一甲虫家族的生物多样性。该项目还开启了一种令人兴奋的可能性，即筛选天牛的肠道转录组是一种微生物替代品，可用于发现新的和更好的多氯联苯WDE，用于工业生物技术，特别是用于改进植物生物质的生物燃料生产。

The charismatic longhorned beetles (Coleoptera: Cerambycidae) are part of the most diverse group of wood-feeding (xylophagous) animals on Earth. Larvae of these beetles have evolved to thrive on a highly challenging and sub-optimal environment - wood material - where they have to cope with the structural polysaccharides of the plant cell wall which make the bulk of their food. Earlier research indicated that cerambycid beetle larvae break down cellulose, hemicelluloses and pectins themselves by producing plant cell wall degrading enzymes (PCWDEs), independent of symbionts. Yet, the corresponding genes and the way they evolved remain elusive in this group of beetles. By combining gene discovery by sequencing beetle midgut transcriptome using RNA-Seq, to phylogenetic analyses and rapid screening of enzymatic activity by expressing the corresponding cDNAs in heterologous expression systems, this project aims to identify and characterize the genes encoding PCWDEs and to determine their evolutionary history in Cerambycidae. This research will provide information on how host plants and feeding behavior have shaped the composition of these gene families during the evolution of Cerambycidae; and on how PCWDEs contributed to build and maintain the biodiversity of this family of beetles. This project also opens the exciting possibility that screening the gut transcriptome of longhorned beetles represents an alternative to microorganisms for the discovery of new and better PCWDEs for use in industrial biotechnology, in particular for the improvement of biofuel production from plant biomass.