Insect-derived extra-oral GH32 plays a role in susceptibility of wheat to Hessian fly.

Authors: Subramanyam, Subhashree; Nemacheck, Jill; BERNAL-CRESPO, VICTOR - Purdue University; SARDESAI, NAGESH - Corteva Agriscience

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2021
Publication Date: 1/22/2021
Citation: Subramanyam, S.N., Nemacheck, J.A., Bernal-Crespo, V., Sardesai, N. 2021. Insect-derived extra-oral GH32 plays a role in susceptibility of wheat to Hessian fly. Scientific Reports. 11, 2081. https://doi.org/10.1038/s41598-021-81481-4.
DOI: https://doi.org/10.1038/s41598-021-81481-4

Interpretive Summary: The Hessian fly causes significant economic damage in wheat. Larval survival on the plant requires the establishment of a steady source of readily available plant nutrition. How this steady source of nutrition was created was not known. In the current study, we show that Hessian fly larvae produce a plant cell wall degrading enzyme (protein) that is secreted into the susceptible wheat plant. This protein breaks down the plant cell wall into simple sugar molecules like glucose and fructose that contribute to the enrichment of a nutrient sink. Understanding the molecular mechanism employed by the insect to establish itself on the plant can help in developing strategies to combat this insect pest and other economically important cereal pests.

Technical Abstract: 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 main 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.