NEW YORK (GenomeWeb) – A team reporting in Genome Biology today has sequenced the genome of the Asian long-horned beetle, Anoplophora glabripennis, uncovering genes suspected of contributing to the insect's destructive wood-feeding ways.
As part of a pilot study for the 5,000 Insect Genomes (i5K) initiative, the researchers from the University of Memphis, Baylor College of Medicine, and elsewhere put together a draft genome assembly for the Asian long-horned beetle, using expression arrays and transcriptome sequences to annotate the genome and characterize the beetle's biological features.
The team detected more than 1,000 genes that appear to be specific to the Asian long-horned beetle, at least compared with more than a dozen arthropod sequences available so far. The group's comparative genomic analysis also pointed to expansions in chemosensory genes and a set of genes coding for glycoside hydrolase enzymes suspected of helping the beetle break down woody material while taking a detoxifying bite out of plant chemicals that would otherwise be dangerous to the insect.
"The arsenal of glycoside hydrolase enzymes that the Asian long-horned beetle has allows it to degrade all of the main polysaccharides present in plant cell walls, releasing the sugars it needs for energy," first author Duane McKenna, a biological sciences researcher at the University of Memphis, said in a statement. "Importantly, the range of enzymes this beetle has is highly diverse, which we believe allows it to breakdown many different molecules present across a wide range of woody plants."
The Asian long-horned beetle is getting more and more attention for its ability to spread to sites around the world, the team noted. As they systematically bore and tunnel into wood from ornamental, orchard, and forest trees, the beetles leave huge economic losses behind them, in the US and beyond.
In an effort to better understand how beetles feed on — and derive nutrition from — woody plants, the researchers used the Illumina HiSeq 2000 to sequence DNA from female Asian long-horned beetle larvae with libraries containing four insert sizes. To that, they added RNA sequence data, including transcriptomes for Asian long-horned beetle larvae grown with varied diet types.
The resulting draft genome assembly spanned about 710 million bases and contained more than 22,000 predicted protein-coding genes. Some 5,029 genes in the Asian long-horned beetle genome appeared to coincide with orthologs across 14 other sequenced insects, the team noted, while thousands more genes were shared with at least one of the other insects considered.
Overall, the researchers found that the Asian long-horned beetle was most closely related to the mountain pine beetle, though the newly sequenced beetle genome contained 1,003 genes with no apparent homologs in the other available arthropod sequences. They noted that the beetle genome housed 86 glycoside hydrolase genes — far more than any other arthropod.
The Asian long-horned beetle genome also had expanded sets of taste receptor genes, cellulase enzymes involved in plant material breakdown, and genes coding for cytochrome P450 enzymes and other proteins involved in plant chemical detoxification.
"Our results … further establish a genomic basis for the invasiveness and broad host plant range of A. glabripennis, and reveal genomic innovations potentially underlying the evolutionary success of insects — especially beetles — on plants," the authors wrote.