Crop Production and Pest Control Research Unit, USDA-ARS, West Lafayette, IN, USA.
Department of Entomology, Purdue University, West Lafayette, IN, USA.
Sci Rep. 2021 Jan 22;11(1):2081. doi: 10.1038/s41598-021-81481-4.
The Hessian fly is an obligate parasite of wheat causing significant economic damage, and triggers either a resistant or susceptible reaction. However, the molecular mechanisms of susceptibility leading to the establishment of the larvae are unknown. Larval survival on the plant requires the establishment of a steady source of readily available nutrition. Unlike other insect pests, the Hessian fly larvae have minute mandibles and cannot derive their nutrition by chewing tissue or sucking phloem sap. Here, we show that the virulent larvae produce the glycoside hydrolase MdesGH32 extra-orally, that localizes within the leaf tissue being fed upon. MdesGH32 has strong inulinase and invertase activity aiding in the breakdown of the plant cell wall inulin polymer into monomers and converting sucrose, the primary transport sugar in plants, to glucose and fructose, resulting in the formation of a nutrient-rich tissue. Our finding elucidates the molecular mechanism of nutrient sink formation and establishment of susceptibility.
小麦北美禾谷缢管蚜是一种专性寄生性昆虫，对小麦造成重大经济损失，并引发抗性或敏感性反应。然而，导致幼虫建立的敏感性的分子机制尚不清楚。幼虫在植物上的生存需要建立一个稳定的、现成的营养来源。与其他害虫不同，小麦北美禾谷缢管蚜幼虫有微小的下颚，不能通过咀嚼组织或吮吸韧皮部汁液来获取营养。在这里，我们表明，毒力幼虫在体外产生糖苷水解酶 MdesGH32，该酶定位于正在取食的叶片组织内。MdesGH32 具有很强的菊粉酶和转化酶活性，有助于将植物细胞壁菊粉聚合物分解成单体，并将植物中主要的运输糖蔗糖转化为葡萄糖和果糖，从而形成富含营养的组织。我们的发现阐明了营养汇形成和敏感性建立的分子机制。
