Tan Yu-Sheng, Mo Bao-Tong, Li Guo-Cheng, Guo Yu-Ruo, Zhang Jian-Zhen, Wang Chen-Zhu
State Key Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, PR China.
CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, PR China.
PLoS Genet. 2025 Jun 3;21(6):e1011744. doi: 10.1371/journal.pgen.1011744. eCollection 2025 Jun.
Myo-inositol, a sugar alcohol produced by most plants, serves as a nutrient and feeding stimulant for many phytophagous insects. Inositol-sensitive taste sensilla have been characterized in many Lepidoptera larvae, but their molecular bases remain unclear. In this study, we determined the gustatory receptors (GRs) for myo-inositol in larva of Helicoverpa armigera, a worldwide crop pest. First, electrophysiological analyses revealed that medial sensilla styloconica strongly responded to myo-inositol and ribose, with weaker responses to xylose, and one GRN inside sensillum may mediate the response to these three chemicals. Based on phylogenetic analysis of sugar GRs of Lepidoptera insects and previous results on Bombyx mori, we then selected two candidate GRs, HarmGR13 and HarmGR11. Using CRISPR-Cas9, we generated knockout mutants for the two GR genes. Knocking out HarmGR13 abolished the responses of the sensilla to myo-inositol, ribose, and xylose, while knocking out HarmGR11 showed no changes. Behavioral assays confirmed that larvae of HarmGR13 homozygous mutant lost the feeding preference to myo-inositol which the wild-type larvae had. Further functional analysis with Xenopus oocytes expressing system and two-electrode voltage-clamping demonstrated that myo-inositol and ribose specifically induced concentration-dependent currents in HarmGR13-expressing oocytes. Structural predictions and molecular docking of HarmGR13 revealed three amino acid residues might be involved in ligand binding. Mutation of these residues resulted in loss of oocyte responses to myo-inositol and ribose. We reveal that HarmGR13 is a receptor that mediates the activity of the cells sensitive to inositol and ribose in larvae, providing new molecular targets for the strategy of regulating the feeding behavior of pests by modifying taste.
肌醇是大多数植物产生的一种糖醇，是许多植食性昆虫的营养物质和取食刺激物。在许多鳞翅目幼虫中已鉴定出对肌醇敏感的味觉感受器，但其分子基础尚不清楚。在本研究中，我们确定了全球农作物害虫棉铃虫幼虫中肌醇的味觉受体（GRs）。首先，电生理分析表明，内侧栓锥形感器对肌醇和核糖有强烈反应，对木糖反应较弱，感器内的一个GRN可能介导对这三种化学物质的反应。基于鳞翅目昆虫糖GRs的系统发育分析和家蚕的先前结果，我们随后选择了两个候选GRs，HarmGR13和HarmGR11。使用CRISPR-Cas9，我们构建了这两个GR基因的敲除突变体。敲除HarmGR13消除了感器对肌醇、核糖和木糖的反应，而敲除HarmGR11则没有变化。行为分析证实，HarmGR13纯合突变体幼虫失去了野生型幼虫对肌醇的取食偏好。利用非洲爪蟾卵母细胞表达系统和双电极电压钳进行的进一步功能分析表明，肌醇和核糖在表达HarmGR13的卵母细胞中特异性诱导浓度依赖性电流。HarmGR13的结构预测和分子对接显示，三个氨基酸残基可能参与配体结合。这些残基的突变导致卵母细胞对肌醇和核糖的反应丧失。我们揭示，HarmGR13是一种介导幼虫中对肌醇和核糖敏感细胞活性的受体，为通过改变味觉来调控害虫取食行为的策略提供了新的分子靶点。
