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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 #418516
Research Project: Regulation, Biosynthesis, and Function of Plant Chemical Defenses and their Role in Climate-Resilient Agriculture

Location: Chemistry Research

Title: Maize big embryo 6 reveals roles of plastidial and cytosolic prephenate aminotransferases in seed and plant development

Author
item LIU, HUI - Orise Fellow
item EL AZAZ CIUDAD, JORGE - University Of Wisconsin
item ABOU, YOBI - University Of Missouri
item YOKOYAMA, RYO - University Of Wisconsin
item WU, SHAN - University Of Florida
item Gorman, Zachary
item CHIN-QEE, ALEC - University Of Florida
item ANGELOVICI, RUTHIE - University Of Missouri
item Block, Anna
item MAEDA, HIROSHI - University Of Wisconsin
item MCCARTY, DONALD - University Of Florida
item SUZUKI, MASAHARU - University Of Florida

Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2025
Publication Date: 6/6/2025
Citation: Liu, H., El Azaz Ciudad, J., Abou, Y., Yokoyama, R., Wu, S., Gorman, Z.J., Chin-Qee, A., Angelovici, R., Block, A.K., Maeda, H.A., Mccarty, D.R., Suzuki, M. 2025. Maize big embryo 6 reveals roles of plastidial and cytosolic prephenate aminotransferases in seed and plant development. The Plant Cell. https://doi.org/10.1093/plcell/koaf067.
DOI: https://doi.org/10.1093/plcell/koaf067

Interpretive Summary: Amino acids are the building blocks for protein synthesis and important for human and animal nutrition. Therefore changing the production of amino acids in crops such as corn can impact their nutritional value. A group of researchers from the ARS in Gainesville FL,the University of Florida, University of Missouri, and University of Wisconsin-Madison, investigated the impact of altering amino acid production in corn and the model plant Arabidopsis. These studies uncovered the different metabolic routes that plants use to make two essential amino acids, and showed that altering which route is used can impact plant size and seed development. This research expands our understanding of how these important nutrients are made, and informs the breeding of crops with increased nutritional value.

Technical Abstract: In plants, embryo size is determined via interactions between metabolic and developmental signals. Maize (Zea mays) big embryo 6 (bige6)enhances embryo size while sharply reducing plant growth. Here, we show that BigE6 encodes a plastidial prephenate aminotransferase (PPA-AT), a key enzyme in the arogenate pathway for L-phenylalanine (Phe) and L-tyrosine (Tyr) biosynthesis. The maize BigE6 paralog, BigE6Like, encodes a cytosol-localized PPA-AT, revealing Phe and Tyr biosynthesis via cytosolic arogenate as a potential alternative to the known cytosolic phenylpyruvate pathway. Moreover, the single PPA-AT gene of Arabidopsis (Arabidopsis thaliana) encodes plastidial and cytosolic enzymes by alternative splicing. Transgenic rescue of a ppa-at mutant in Arabidopsis demonstrates that the plastidial PPA-AT is indispensable for seed formation due, in part, to its essential role in the female gametophyte. Leaves of bige6 maize maintained overall homeostasis for aromatic amino acids and downstream metabolites, revealing a resilience of mechanisms that scale growth to a limiting supply of Phe and Tyr. In bige6 seeds, broad perturbation of amino acid homeostasis is associated with transcriptomic upregulation of growth processes in the embryo and endosperm, implicating amino acid signaling in the regulation of embryo size. Our findings reveal the complexity and developmental dependence of growth responses to limiting amino acid biosynthesis.