Larvae of longhorned beetles (Coleoptera; Cerambycidae) have evolved a diverse and phylogenetically conserved array of plant cell wall degrading enzymes
Larvae of longhorned beetles (Coleoptera; Cerambycidae) have evolved a diverse and phylogenetically conserved array of plant cell wall degrading enzymes
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DOI：
10.1111/syen.12488
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发表时间：
2021-05
影响因子：
4.8
通讯作者：
Na Ra Shin;Seunggwan Shin;Yu Okamura;Roy Kirsch;V. Lombard;P. Švácha;O. Denux;S. Augustin;B. Henrissat;D. Mckenna;Y. Pauchet
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作者：
Na Ra Shin;Seunggwan Shin;Yu Okamura;Roy Kirsch;V. Lombard;P. Švácha;O. Denux;S. Augustin;B. Henrissat;D. Mckenna;Y. Pauchet
长角甲虫（天牛科）是地球上种类最多的主要食木昆虫。大多数种类的幼虫在由大量植物细胞壁（PCW）组成的植物组织中摄食，这是众所周知的难以消化。为了有效地从食物来源获取营养，天牛幼虫必须分解PCW多糖，如纤维素、半纤维素和果胶，这就要求它们在消化道中拥有多种植物细胞壁降解酶（PCWDEs）。天牛科的基因组数据大多局限于臭名昭著的森林害虫，大多数分类类群都缺乏。因此，我们对神经酰胺类pcwde的分布和演化的认识非常有限。我们通过对来自23个物种的幼虫中肠转录组的研究，研究了天牛科8个亚科中的6个，每个亚科都有非常不同的寄主类型（即裸子植物、被子植物、木质部、韧皮部、新鲜或死亡的植物组织），研究了天牛科PCWDEs的数量、种类和进化。利用这些数据，我们确定了340个新的推定pcwde，属于10个碳水化合物活性酶家族，包括两个先前未报道的昆虫基因家族（GH7和GH53）。天牛科表达的pcwde的范围非常广，这应该使它们能够分解大多数PCW多糖。此外，观察到的编码在神经酰胺基因组中的PCWDEs分布更符合所研究物种的系统发育关系，而不是寄主植物组织的分类起源或质量。
Longhorned beetles (Cerambycidae) are the most diverse group of predominantly wood‐feeding (xylophagous) insects on Earth. Larvae of most species feed within tissues of plants made up of large amounts of plant cell wall (PCW), which is notoriously difficult to digest. To efficiently access nutrients from their food source, cerambycid larvae have to deconstruct PCW polysaccharides – such as cellulose, hemicelluloses and pectin – requiring them to possess a diversity of plant cell wall degrading enzymes (PCWDEs) in their digestive tract. Genomic data for Cerambycidae are mostly limited to notorious forest pests and are lacking for most of the taxonomic groups. Consequently, our understanding of the distribution and evolution of cerambycid PCWDEs is quite limited. We addressed the numbers, kinds and evolution of cerambycid PCWDEs by surveying larval midgut transcriptomes from 23 species representing six of the eight recognized subfamilies of Cerambycidae and each with very diverse host types (i.e., gymnosperms, angiosperms, xylem, phloem, fresh or dead plant tissues). Using these data, we identified 340 new putative PCWDEs belonging to ten carbohydrate active enzyme families, including two gene families (GH7 and GH53) not previously reported from insects. The remarkably wide range of PCWDEs expressed by Cerambycidae should allow them to break down most PCW polysaccharides. Moreover, the observed distribution of PCWDEs encoded in cerambycid genomes agreed more with phylogenetic relationship of the species studied than with the taxonomic origin or quality of the host plant tissues.