Chromosome-level genome assembly for the horned-gall aphid provides
insights into interactions between gall-making insect and its host plant
The horned gall aphid Schlechtendalia chinensis, is an economically
important insect that induces galls valuable for medicinal and chemical
industries. S. chinensis manipulates its host plant to form
well-organized horned galls during feeding. So far, more than twenty
aphid genomes have been reported; however, all of those are derived from
free-living aphids. Here we generated a high-quality genome assembly of
S. chinensis, representing the first genome sequence of a galling aphid.
The final genome assembly was 280.43 Mb, with 97% of the assembled
sequences anchored into thirteen chromosomes. S. chinensis presents the
smallest aphid genome size among available aphid genomes to date. The
contig and scaffold N50 values were 3.39 Mb and 20.58 Mb, respectively.
The assembly included 96.4% of conserved arthropod and 97.8% of
conserved Hemiptera single-copy orthologous genes based on BUSCO
analysis. A total of 13,437 protein-coding genes were predicted.
Phylogenomic analysis showed that S. chinensis formed a single clade
between the Eriosoma lanigerum clade and the Aphidini+Macrosiphini aphid
clades. In addition, salivary proteins were found to be differentially
expressed when S. chinensis underwent host alternation, indicating their
potential roles in gall formation and plant defense suppression. A total
of 36 cytochrome P450 genes were identified in S. chinensis,
considerably fewer compared to other aphids, probably due to its small
host plant range. The high-quality S. chinensis genome assembly and
annotation provide an essential genetic background for future studies to
reveal the mechanism of gall formation and to explore the interaction
between aphids and their host plants.