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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Chemistry Research » Research » Publications at this Location » Publication #393190
Research Project: Molecular and Biochemical Characterization of Biotic and Abiotic Stress on Plant Defense Responses in Maize

Location: Chemistry Research

Title: Metabolic link between auxin production and specialized metabolites in Sorghum bicolor

Author
item PEREZ, VERONICA - University Of Florida
item DAI, RU - University Of Florida
item TOMICZEK, BREANNA - University Of Florida
item Mendoza, Jorrel
item GREENING, ALEXANDER - University Of Florida
item REED, EMILY - University Of Florida
item VERMERRIS, WILFRED - University Of Florida
item Block, Anna
item KIM, JEONGIM - University Of Florida

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2022
Publication Date: 10/27/2022
Citation: Perez, V.C., Dai, R., Tomiczek, B., Mendoza, J.S., Greening, A., Reed, E.S., Vermerris, W., Block, A.K., Kim, J. 2023. Metabolic link between auxin production and specialized metabolites in Sorghum bicolor. Journal of Experimental Botany. 74:364-376. https://doi.org/10.1093/jxb/erac421.
DOI: https://doi.org/10.1093/jxb/erac421

Interpretive Summary: Plants control their growth and development using plant hormones such as auxins. These growth controlling compounds are made using a variety of pathways depending on the needs of the plants. In this study researchers from the University of Florida and USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, FL uncovered a route for hormone biosynthesis in the crop plant sorghum that uses the chemical compound benzyl cyanide as an intermediate. When produced by plants, benzyl cyanide has been shown to be toxic to some crop damaging insects. These findings suggest unexpected interconnections between plant defense and growth regulation in addition to providing insights how sorghum responds when attacked by insect pests.

Technical Abstract: Aldoximes are amino acid derivatives that serve as intermediates for numerous specialized metabolites including cyanogenic glycosides, glucosinolates, and auxins. Aldoxime formation is mainly catalyzed by cytochrome P450 monooxygenases of the 79 family (CYP79s) which can have broad or narrow substrate specificity. This study identified nine CYP79-encoding genes from the genome of sorghum (Sorghum bicolor) and among the sequences identified one, SbCYP79A61, was found to form a subclade with the previously characterized maize ZmCYP79A61. Functional characterization of this enzyme using transient expression in Nicotiana benthamiana and stable overexpression in Arabidopsis thaliana revealed that SbCYP79A61 catalyzes the production of phenylacetaldoxime (PAOx) from phenylalanine but not indole-3-acetaldoxime (IAOx) from tryptophan. Additionally, targeted metabolite analysis after unlabeled and stable isotope feeding assays revealed that PAOx can serve as a precursor of phenylacetic acid (PAA) in sorghum and identified benzyl cyanide as an intermediate of PAOx-derived PAA biosynthesis in both sorghum and maize. Taken together, our results demonstrate that SbCYP79A61 produces PAOx in sorghum and may serve in the biosynthesis of other nitrogen-containing phenylalanine-derived metabolites.