Evolutionary shifts in taste coding in the fruit pest Drosophila suzukii.
Evolutionary shifts in taste coding in the fruit pest Drosophila suzukii.
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DOI：
10.7554/elife.64317
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发表时间：
2021-02-22
期刊：
影响因子：
7.7
通讯作者：
Carlson JR
中科院分区：
文献类型：
--
作者：
Dweck HK;Talross GJ;Wang W;Carlson JR
尽管大多数果蝇物种在过熟的果实中产卵，但农业害虫铃木果蝇却在成熟的果实中产卵。我们发现苦味感知的变化伴随着这种适应。我们发现，黑腹果蝇的苦味感知突变体的产卵偏好发生了向成熟果实的转变。铃木 D. suzukii 失去了 20% 的唇瓣（头部主要味觉器官）的苦味感受器。对各种苦味化合物的生理反应消失。两类味觉感受器失去了对草莓泥的反应。产卵不会受到阻碍其他物种的苦味化合物的影响。标签转录组分析揭示了几种苦味 Gr 基因（味觉受体）的表达减少。这些发现支持了一种模型，即早期成熟阶段的苦味化合物会阻止大多数果蝇物种产卵，但苦味反应的丧失有助于铃木果蝇适应成熟的果实。最近在美国和北欧出现了一种新的农业害虫。这种入侵物种是一种通常生活在东南亚的果蝇，称为铃木果蝇（也称为斑翅果蝇）。这种苍蝇对水果作物（包括草莓、蓝莓、樱桃、桃子和葡萄）构成威胁，因为其他果蝇在熟透的水果中产卵，而铃木果蝇则在成熟的水果中产卵，从而导致农业损失。果蝇更喜欢产卵的地方的这种变化与嗅觉和触觉的变化有关，味觉也可能发挥作用。昆虫进化出了一种机制，可以阻止它们进食或产卵于含有大量毒素且味道苦涩的植物中。如果铃木果蝇对苦味的敏感度低于其他果蝇，这可能有助于解释为什么它会在刚成熟的果实中产卵，因为某些苦味化合物的含量在成熟的早期阶段比后期更高。为了弄清楚情况是否如此，Dweck 等人。研究了不同种类的果蝇。与黑腹果蝇（一种常见于美国和欧洲，经常用于科学研究的果蝇）相比，铃木果蝇头部主要味觉器官上的苦味受体神经元较少。这些受体神经元对各种苦味化合物的反应也较差。接下来，德韦克等人。通过向黑腹果蝇和铃木果蝇提供由不同成熟阶段的水果制成的草莓泥，测试了它们是否对产卵地点表现出不同的偏好。在这个实验中，铃木果蝇更喜欢在未成熟或刚刚成熟的草莓果泥上产卵，而黑腹果蝇则偏爱发酵（过熟）的果泥。此外，当黑腹果蝇经过基因改造后，它们对苦味的敏感度降低，它们更喜欢在成熟（而不是过熟）的水果中产卵，与铃木果蝇类似。这些结果表明味觉在铃木石斑鱼的产卵偏好中起着重要作用。需要进一步的研究来确定哪些苦味化合物会影响每种果蝇的产卵决定，以及哪些受体对这些化合物有反应。然而，Dweck 等人的研究结果为减少铃木 D. suzukii 对农业影响的新方法奠定了基础。
Although most Drosophila species lay eggs in overripe fruit, the agricultural pest Drosophila suzukii lays eggs in ripe fruit. We found that changes in bitter taste perception have accompanied this adaptation. We show that bitter-sensing mutants of Drosophila melanogaster undergo a shift in egg laying preference toward ripe fruit. D. suzukii has lost 20% of the bitter-sensing sensilla from the labellum, the major taste organ of the head. Physiological responses to various bitter compounds are lost. Responses to strawberry purées are lost from two classes of taste sensilla. Egg laying is not deterred by bitter compounds that deter other species. Profiling of labellar transcriptomes reveals reduced expression of several bitter Gr genes (gustatory receptors). These findings support a model in which bitter compounds in early ripening stages deter egg laying in most Drosophila species, but a loss of bitter response contributes to the adaptation of D. suzukii to ripe fruit. A new agricultural pest has recently emerged in the United States and Northern Europe. The invasive species is a type of fruit fly that normally lives in Southeast Asia called Drosophila suzukii (also known as the spotted wing Drosophila). This fly poses a threat to fruit crops – including strawberries, blueberries, cherries, peaches and grapes – because, while other fruit flies lay eggs in overripe fruit, D. suzukii lays eggs in ripe fruit, leading to agricultural losses. This shift in where fruit flies prefer to lay their eggs is related to changes in the senses of smell and touch, and taste could also play a role. Insects have evolved mechanisms that dissuade them from eating or laying eggs in plants with high levels of toxins, which taste bitter. If D. suzukii is less sensitive to bitter tastes than other flies, this could help explain why it lays eggs in just-ripe fruit, since the levels of certain bitter compounds are higher in the early stages of ripening than later on. To figure out if this is the case, Dweck et al. studied different species of fruit fly. Compared to Drosophila melanogaster (a fruit fly common in America and Europe that is regularly used in scientific studies), D. suzukii had fewer bitter taste receptor neurons on the major taste organ of the fly head. These receptor neurons were also less responsive to a variety of bitter compounds. Next, Dweck et al. tested whether D. melanogaster and D. suzukii showed different preferences for where to lay their eggs by offering them strawberry purées made from fruit at different ripening stages. In this experiment, D. suzukii preferred to lay its eggs on purées made from unripe or just-ripe strawberries, while D. melanogaster showed a preference for fermented (overripe) purée. Furthermore, when D. melanogaster flies were genetically modified so that they became less sensitive to bitter taste, they preferred to lay their eggs in ripe (rather than overripe) fruit, similar to D. suzukii. These results suggest that taste has a major role in the egg laying preferences of D. suzukii. Further research is needed to determine which bitter compounds influence egg-laying decisions in each species of fruit fly, and what receptors respond to these compounds. However, Dweck et al.’s results lay the groundwork for new approaches to reducing D. suzukii’s impact on agriculture.