A determining factor for insect feeding preference in the silkworm, Bombyx mori
A determining factor for insect feeding preference in the silkworm, Bombyx mori
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蚕（Bombyx mori）昆虫取食偏好的决定因素。
DOI：
10.1371/journal.pbio.3000162
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发表时间：
2019-02-01
期刊：
影响因子：
9.8
通讯作者：
Tan, An-Jiang
中科院分区：
文献类型：
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作者：
Zhang, Zhong-Jie;Zhang, Shuai-Shuai;Tan, An-Jiang
取食偏好是昆虫适应和生存的关键。然而，人们对昆虫取食偏好的决定知之甚少，对其遗传基础也知之甚少。家蚕是一种著名的单食性昆虫，主要以新鲜桑叶为食，是一种具有重要经济价值的模式鳞翅目昆虫。这种特定物种的取食偏好为研究寄主-植物对昆虫的选择提供了一个很好的模型，尽管这种现象背后的分子机制尚不清楚。在这里，我们描述了基因GR66，它编码一个可能的苦味受体(GR)，负责桑树特异性的取食偏好。利用以转座子为基础的簇状规则间隔短回文重复序列(CRISPR)/CRISPR相关蛋白-9核酸酶(Cas9)系统，对家蚕GR66基因座进行了遗传突变，建立了GR66蛋白截短的纯合突变家蚕品系。GR66突变幼虫获得了新的取食活动，表现出除桑叶外还能捕食许多植物物种的能力，包括新鲜水果和野生(WT)家蚕通常不会消耗的谷物种子。此外，取食选择试验表明，突变幼虫失去了对桑树的专一性。总体而言，我们的发现首次提供了遗传和表型证据，证明单一的苦味GR是影响昆虫取食偏好的主要因素。
Feeding preference is critical for insect adaptation and survival. However, little is known regarding the determination of insect feeding preference, and the genetic basis is poorly understood. As a model lepidopteran insect with economic importance, the domesticated silkworm, Bombyx mori, is a well-known monophagous insect that predominantly feeds on fresh mulberry leaves. This species-specific feeding preference provides an excellent model for investigation of host-plant selection of insects, although the molecular mechanism underlying this phenomenon remains unknown. Here, we describe the gene GR66, which encodes a putative bitter gustatory receptor (GR) that is responsible for the mulberry-specific feeding preference of B. mori. With the aid of a transposon-based, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 nuclease (Cas9) system, the GR66 locus was genetically mutated, and homozygous mutant silkworm strains with truncated gustatory receptor 66 (GR66) proteins were established. GR66 mutant larvae acquired new feeding activity, exhibiting the ability to feed on a number of plant species in addition to mulberry leaves, including fresh fruits and grain seeds that are not normally consumed by wild-type (WT) silkworms. Furthermore, a feeding choice assay revealed that the mutant larvae lost their specificity for mulberry. Overall, our findings provide the first genetic and phenotypic evidences that a single bitter GR is a major factor affecting the insect feeding preference.