Transcriptomic and volatile signatures associated with maize defense against corn leaf aphid

Authors: PINGAULT, LISE - University Of Nebraska; VARSANI, SURESH - University Of Nebraska; Palmer, Nathan - Nate; RAY, SWAYAMJIT - State College Of Pennsylvania; Williams, William; LUTHE, DAWN - State College Of Pennsylvania; ALI, JARED - State College Of Pennsylvania; Sarath, Gautam; LOUIS, JOE - University Of Nebraska

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2021
Publication Date: 3/16/2021
Publication URL: https://handle.nal.usda.gov/10113/7311312
Citation: Pingault, L., Varsani, S., Palmer, N.A., Ray, S., Williams, W.P., Luthe, D.S., Ali, J.G., Sarath, G., Louis, J. 2021. Transcriptomic and volatile signatures associated with maize defense against corn leaf aphid. Biomed Central (BMC) Plant Biology. 21:138. https://doi.org/10.1186/s12870-021-02910-0.
DOI: https://doi.org/10.1186/s12870-021-02910-0

Interpretive Summary: Maize is a major cereal crop whose production can be negatively impacted by insect pests. The corn leaf aphid (CLA) is a significant aphid pest that can also transmit viral pathogens to corn plants. Finding maize genotypes that are broadly resistant to CLA can aid breeding of commercial maize cultivars with improved traits. In this study short-term biochemical and gene-expression profile differences between a resistant line (Mp708) and a susceptible line (TX601) infested with CLA were investigated. The goal was to differentiate physiological features that could account for initial resistance to CLA. Studies indicated that the resistant line apparently regulated plant hormone signaling in response to insect herbivory as compared to the susceptible line. Additionally, different volatile chemicals were emitted by the resistant and susceptible lines. Plant volatile organic compounds can often act as attractants of beneficial insect species.

Technical Abstract: Maize (Zea mays L.) is a major cereal crop, with the United States accounting for over 40% of the worldwide production. Corn leaf aphid [CLA; Rhopalosiphum maidis (Fitch)] is an economically important pest of maize and several other monocot crops. In addition to feeding damage, CLA acts as a vector for viruses that cause devastating diseases in maize. We have shown previously that the maize inbred line Mp708, which was developed by classical plant breeding, provides heightened resistance to CLA. However, the transcriptomic variation conferring CLA resistance to Mp708 has not been investigated. In this study, we contrasted the defense responses of the resistant Mp708 genotype to those of the susceptible Tx601 genotype at the transcriptomic (mRNA-seq) and volatile blend levels. Our results suggest that there was a greater ranscriptomic remodeling in Mp708 plants in response to CLA infestation compared to the Tx601 plants. These transcriptomic signatures indicated an activation of hormonal pathways, and regulation of sesquiterpenes and terpenoid synthases in a constitutive and inducible manner. Transcriptomic analysis also revealed that the resistant Mp708 genotype possessed distinct regulation of ethylene and jasmonic acid pathways before and after aphid infestation. Finally, our results also highlight the significance of constitutive production of volatile organic compounds (VOCs) in Mp708 and Tx601 plants that may contribute to maize direct and/or indirect defense responses. This study provided further insights to understand the role of defense signaling networks in Mp708’s resistance to CLA.