Insect-Resistant Variety Populus deltoides ‘Shalinyang’ May Decrease Anoplophora glabripennis Females’ Fecundity by Suppressing the Serine/Threonine Kinase AglaAkt Gene

TL;DR

A new poplar variety called Shalinyang reduces the reproduction of Asian longhorned beetles by suppressing a key gene in their gut.

Contribution

The study identifies AglaAkt as a novel target gene involved in the reproductive response of Anoplophora glabripennis to resistant poplar.

Findings

AglaAkt gene expression is significantly lower in beetles feeding on Shalinyang poplar.

RNA interference of AglaAkt leads to reduced vitellogenin and vitellin levels in female beetles.

The PIK3-Akt signaling pathway is suppressed in beetles consuming Shalinyang poplar.

Abstract

The Asian longhorned beetle (ALB), Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae), is a highly destructive wood-boring pest that causes significant damage to poplar trees in farmland shelterbelts across Northwest China. Populus deltoides ‘Shalinyang’ (PdS) is a new stress-resistant poplar variety developed by the Chinese Academy of Forestry and shows resistance to ALB. It can be used as an “attract-and-kill” tree in mixed shelterbelt construction. However, the mechanisms behind PdS’s effects on the growth, development, and reproduction of ALB are not fully understood. In this study, transcriptomic analysis and quantitative real-time PCR showed that the serine/threonine kinase AglaAkt gene expression in the midgut of ALB females fed on PdS was significantly lower than in those fed on either Elaeagnus angustifolia L. or Salix matsudana Koidz. Subsequently, RNA interference-mediated silencing of AglaAkt resulted in decreased vitellogenin production and impaired vitellin deposition in female beetles. These results suggest that AglaAkt may be a key target gene involved in the response to PdS and may contribute to the reduced fecundity observed in ALB.

Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae) is notorious for its wide host range, serious damage caused, and the difficulties involved in controlling it. Populus deltoides ‘Shalinyang’ (PdS) has demonstrated a strong inhibitory effect on the larval growth and the adult lifespan of A. glabripennis and can be used as an “attract-and-kill” tree in mixed shelterbelt construction. However, how A. glabripennis react to this resistant poplar remains unclear. This research employed transcriptomics techniques to study transcriptional responses in the midgut of A. glabripennis after consuming PdS, Elaeagnus angustifolia L. (EA), and Salix matsudana Koidz (SM), respectively. One of the key findings revealed that the PIK3-Akt signaling pathway was suppressed in A. glabripennis feeding on PdS compared with those feeding on EA or SM. Further RNA interference results demonstrated that silencing the AglaAkt gene significantly decreased the levels of AKT, phospho-AKT, vitellogenin, vitellogenin receptor, and vitellin in A. glabripennis. Therefore, we speculate that the AglaAkt gene may be an underlying target gene that causes the low reproductive capacity of A. glabripennis when feeding on PdS. This finding provides important insights into the role of the AglaAkt gene in mediating the reproductive development in A. glabripennis and its molecular response to the resistant poplar.

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