Duplication and expression of horizontally transferred polygalacturonase genes is associated with host range expansion of mirid bugs

Abstract

BackgroudHorizontal gene transfer and gene duplication are two major mechanisms contributing to the evolutionary adaptation of organisms. Previously, polygalacturonase genes (PGs) were independently horizontally transferred and underwent multiple duplications in insects (e.g., mirid bugs and beetles). Here, we chose three phytozoophagous mirid bugs (Adelphocoris suturalis, A. fasciaticollis, A. lineolatus) and one zoophytophagous mirid bug (Nesidiocoris tenuis) to detect whether the duplication, molecular evolution, and expression levels of PGs were related to host range expansion in mirid bugs.ResultsBy RNA-seq, we reported 30, 20, 19 and 8 PGs in A. suturalis, A. fasciaticollis, A. lineolatus and N. tenuis, respectively. Interestingly, the number of PGs was significantly positive correlation to the number of host plants (P = 0.0339) in mirid bugs. Most PGs (> 17) were highly expressed in the three phytozoophagous mirid bugs, while only one PG was relatively highly expressed in the zoophytophagous mirid bug. Natural selection analysis clearly showed that a significant relaxation of selection pressure acted on the PGs in zoophytophagous mirid bugs (K = 0.546, P = 0.0158) rather than in phytozoophagous mirid bugs (K = 1, P = 0.92), suggesting a function constraint of PGs in phytozoophagous mirid bugs.ConclusionTaken together with gene duplication, molecular evolution, and expression levels, our results suggest that PGs are more strictly required by phytozoophagous than by zoophytophagous mirid bugs and that the duplication of PGs is associated with the expansion of host plant ranges in mirid bugs.Electronic supplementary materialThe online version of this article (10.1186/s12862-019-1351-1) contains supplementary material, which is available to authorized users.

Apolygus lucorum genome provides insights into omnivorousness and mesophyll feeding

“…PG is a group of plant cell wall‐degrading enzyme, ubiquitous in fungi, bacteria, and plants. It is also found in Hemiptera and Coleoptera, predicted to be horizontally transferred from fungi (Wybouw et al., 2016; Xu et al., 2019). PG activity has been detected in the salivary glands of Hemiptera including some aphid species, but is especially common in mirid bugs (Zhang et al., 2015).…”

“…Some strictly phytophagous mirid bugs even lack detectable digestive proteases (Cohen & Wheeler, 1998). The expansion of SPs in A. lucorum can improve its digestive capacity and may contribute to its omnivorous feeding habit, mainly phytophagous with prey to complement (Li, et al., 2019; Xu et al., 2019). The slight expansion of SPs was also observed in bed bug, which is consistent with its carnivorous feeding habit.…”

The evolution of opsin genes in five species of mirid bugs: duplication of long-wavelength opsins and loss of blue-sensitive opsins

“…fasciaticollis and Ad. lineolatus [ 6 , 34 , 35 ]) and one zoophytophagous species ( N. tenuis [ 2 , 3 ]). We identified four opsin-like contigs in Ap.…”

Jekyll or Hyde? The genome (and more) of Nesidiocoris tenuis, a zoophytophagous predatory bug that is both a biological control agent and a pest

“…With all of these fascinating avenues of research in mind, it may be surprising to learn that, aside from a mitogenome (Dai et al ., 2012), a regional population analysis (Xun et al ., 2016) and more recent work shedding light on evidence of LGT (Xu et al ., 2019b), little genomic information exists for N. tenuis and there is no published N. tenuis genome. Characteristics such as karyotype, sex chromosome system and presence or absence of telomeric repeats are currently unknown.…”