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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #394098
Research Project: Improving Forage and Bioenergy Plants and Production Systems for the Central U.S.

Location: Wheat, Sorghum and Forage Research

Title: Dynamic regulation of phenylpropanoid pathway metabolites in modulating sorghum defense against fall armyworm

Author
item GROVER, SAJJAN - University Of Nebraska
item SHINDE, SANKET - University Of Nebraska
item PURI, HEENA - University Of Nebraska
item Palmer, Nathan - Nate
item Sarath, Gautam
item Sattler, Scott
item LOUIS, JOE - University Of Nebraska

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2022
Publication Date: 11/25/2022
Citation: Grover, S., Shinde, S., Puri, H., Palmer, N.A., Sarath, G., Sattler, S.E., Louis, J. 2022. Dynamic regulation of phenylpropanoid pathway metabolites in modulating sorghum defense against fall armyworm. Frontiers in Plant Science. 13:1019266. https://doi.org/10.3389/fpls.2022.1019266.
DOI: https://doi.org/10.3389/fpls.2022.1019266

Interpretive Summary: Larvae of chewing insects such as the fall armyworm (FAW) attack sorghum plants. Plants respond to insect oral secretions and tissue damage by inducing defense responses. One plant defense response is the synthesis of compounds that limit FAW feeding. In this study, the role of purple compounds plants produce called flavonoids were evaluated in resistant and susceptible sorghum plants. The resistant sorghum line SC1345 had elevated levels of flavonoids compared to the susceptible Ajabsido plants following FAW feeding and the application of FAW oral secretions in the absence of the insects. The gene associated with flavonoid biosynthesis were also induced, which further supported a role for these compounds in sorghum resistance. This study suggested a novel mechanism allows the resistant plants to make more of the flavonoid compounds in comparison to the susceptible ones.

Technical Abstract: Plants undergo dynamic metabolic changes at the cellular level upon insect infestation to better defend themselves. Phenylpropanoids, a hub of secondary plant metabolites, encompass a wide range of compounds that can contribute to insect resistance. Here, the role of sorghum phenylpropanoids in providing defense against the chewing herbivore, fall armyworm (FAW), Spodoptera frugiperda, has been explored. We screened a panel of nested association mapping (NAM) founder lines against FAW and identified SC1345 and Ajabsido as most resistant and susceptible lines to FAW, respectively, compared to reference parent, RTx430. Gene expression and metabolomic studies suggested that FAW feeding suppressed the expression level of genes involved in monolignol biosynthetic pathway and their associated phenolic intermediates after 10 days of feeding (dpi). Further studies showed that SC1345 displayed elevated levels of flavonoid compounds 10 dpi, suggesting a metabolic spill over from lignin biosynthesis to the flavonoid pathway. A FAW bioassay with sorghum lines having altered levels of flavonoids suggested that flavonoids are crucial in providing resistance against FAW. Additionally, application of FAW regurgitants on wounded plants showed elevated expression level of genes involved in flavonoid pathway. Overall, our study indicates that a dynamic regulation of metabolic flux in the phenylpropanoid pathway in sorghum plants imparts resistance against FAW.