Virus-induced gene silencing simultaneously exploits ‘attract and kill’ traits in plants and insects to manage huanglongbing Open Access

Abstract

The vector-borne disease huanglongbing (HLB) causes severe economic losses to citrus production worldwide with no available cure. Herein, we applied virus-induced gene silencing technology to engineer citrus that preferentially attracted and specifically killed Diaphorina citri, the vector associated with HLB. We engineered the infectious citrus tristeza virus (CTV-T36) clone to carry three truncated genes. The triple construct (CTV-tAwd-tWnt-tPDS) produces small interfering RNAs (siRNAs) against phytoene desaturase, PDS, to yield a phenotype with visual, olfactory, and gustatory cues that preferentially attracted D. citri. In addition, siRNAs targeted two genes related to flight in D. citri, abnormal wing disc (DcAwd) and wingless (DcWnt), that caused wing malformations and decreased survival in psyllids that fed on plants inoculated with the engineered virus. During two successive generations, D. citri reared on CTV-tAwd-tWnt-tPDS-inoculated plants exhibited higher mortality across life stages as well as reduced fecundity and fertility as compared with those reared on noninfected plants or CTV-wt-inoculated plants. Furthermore, CTV-tAwd-tWnt-tPDS-inoculated plants shortened the lifespan of D. citri by more than 20 days. Morphological abnormalities were noted in those adults that did successfully emerge on plants inoculated with CTV-tAwd-tWnt-tPDS, including cocked wings with a bowl-shaped depression and/or a convex shape. Phloem sap from CTV-tAwd-tWnt-tPDS-inoculated plants decreased the survival of D. citri adults, confirming that siRNAs were present in the sap of these plants. Collectively, we provide proof of concept for a novel variant of the attract-and-kill method where the cultivated crop is potentially transformed into a hyper-attractive population and transmission sink for a phytopathogen vector.

Acknowledgements

The authors wish to acknowledge the members of our laboratory for helpful discussions and comments. This project was supported by the Emergency Citrus Diseases Research and Extension grants program, Award number 2020-70029-33177 from the USDA National Institute of Food and Agriculture.

Author contributions

N.K. conceived the project and experiments. S.G. and S.H. created the vector construct and genetic analysis of transgenic plants. N.K. performed attraction/preference assay, developmental progression, and survival of D. citri. N.K. and Y.N. analyzed the data and visualized the figures. N.K., Y.N., and L.L. wrote the manuscript with input and edits from all co-authors. All authors read and approved the manuscript.

Data availability

All relevant data that support the findings of this study can be found within the article.

Conflict of interest disclosure

The authors have declared that no competing interests exist.

Supplementary Data

Supplementary data is available at Horticulture Research online.

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