|XIE, SHAOJUN - Purdue University|
|BHIDE, KETAKI - Purdue University|
|THIMMAPURAM, JYOTHI - Purdue University|
|Scofield, Steven - Steve|
|SARDESAI, NAGESH - Corteva Agriscience|
Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2021
Publication Date: 10/25/2021
Citation: 1. Subramanyam, S., Nemacheck, J.A., Xie, S., Bhide, K., Thimmapuram, J., Scofield, S.R., Sardesai N. 2021. Comparative Hessian fly larval transcriptomics provides novel insight into host and nonhost resistance. International Journal of Molecular Sciences. 22(21): 11498. https://doi.org/10.3390/ijms222111498
Interpretive Summary: The Hessian fly is a destructive pest of host wheat causing severe economic losses in yield worldwide. Understanding the methods employed by this insect pest, that makes the plant vulnerable, is crucial to develop effective management strategies. Brachypodium distachyon is not a host of Hessian flies but is resistant to the damage caused and provides advantages as an experimental system as its genome is much less complex than wheat’s. In this study we compared the gene expression changes in Hessian fly larvae feeding on resistant and vulnerable host wheat and nonhost resistant B. distachyon plants. We identified genes belonging to different functional categories that are unique and common between larvae feeding on host and nonhost plants. We highlight the changes that occur in larvae feeding on resistant and vulnerable wheat and compare with those in larvae feeding on nonhost plants. The information obtained from this study will benefit scientists worldwide to develop strategies to control this devastating insect pest.
Technical Abstract: The Hessian fly is a destructive pest of wheat. Employing additional molecular strategies can complement wheat native insect resistance. However, this requires functional characterization of Hessian fly-responsive genes which is challenging because of wheat genome complexity. The diploid Brachypodium distachyon (Bd) exhibits nonhost resistance to Hessian fly and displays phenotypic/molecular responses intermediate between resistant and susceptible host wheat, offering a surrogate genome for gene characterization. Here, we compared the transcriptomes of Biotype L larvae residing on resistant/susceptible wheat, and nonhost Bd plants. Larvae from susceptible wheat and nonhost Bd plants revealed similar molecular responses that were distinct from avirulent larval responses on resistant wheat. Secreted salivary gland proteins were strongly up-regulated in all larvae. Genes from various biological pathways and molecular processes were up-regulated in larvae from both susceptible wheat and nonhost Bd plants. However, Bd larval expression levels were intermediate between larvae from susceptible and resistant wheat. Most genes were down-regulated or unchanged in avirulent larvae correlating with their inability to establish feeding sites and dying within 4-5 days after hatch. Decreased gene expression in Bd larvae, compared to ones on susceptible wheat, potentially led to developmentally delayed 2nd instars followed by eventually succumbing to nonhost resistance defense mechanisms.