Aidlin Harari Ofer, Dekel Amir, Wintraube Dor, Vainer Yuri, Mozes-Koch Rita, Yakir Esther, Malka Osnat, Morin Shai, Bohbot Jonathan D
Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel.
iScience. 2023 Apr 29;26(5):106752. doi: 10.1016/j.isci.2023.106752. eCollection 2023 May 19.
In insects, specialized feeding on the phloem sap (containing mainly the sugar sucrose) has evolved only in some hemipteran lineages. This feeding behavior requires an ability to locate feeding sites buried deeply within the plant tissue. To determine the molecular mechanism involved, we hypothesized that the phloem-feeding whitefly relies on gustatory receptor (GR)-mediated sugar sensing. We first conducted choice assays, which indicated that adults consistently choose diets containing higher sucrose concentrations. Next, we identified four genes in the genome. One of them, , displayed significant sucrose specificity when expressed in oocytes. Silencing of significantly interfered with the ability of adults to discriminate between non-phloem and phloem concentrations of sucrose. These findings suggest that in phloem feeders, sugar sensing by sugar receptors might allow tracking an increasing gradient of sucrose concentrations in the leaf, leading eventually to the location of the feeding site.
在昆虫中，专门取食韧皮部汁液（主要含蔗糖）的习性仅在某些半翅目类群中进化而来。这种取食行为需要具备定位深埋于植物组织内取食位点的能力。为了确定其中涉及的分子机制，我们推测以韧皮部为食的粉虱依赖味觉受体（GR）介导的糖类感知。我们首先进行了选择试验，结果表明成虫始终会选择蔗糖浓度更高的食物。接下来，我们在基因组中鉴定出四个基因。其中一个基因，在卵母细胞中表达时表现出显著的蔗糖特异性。该基因的沉默显著干扰了成虫区分非韧皮部和韧皮部蔗糖浓度的能力。这些发现表明，在以韧皮部为食的昆虫中，糖类受体对糖类的感知可能有助于追踪叶片中蔗糖浓度不断增加的梯度，最终找到取食位点。
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