Unlocking translational control of specialized metabolism in plants through 5'UTR structure.

Abstract

Plant-specialized metabolites are essential for plant fitness and human health, with their biosynthesis pathways tightly regulated at multiple levels. However, the translational regulation of their biosynthesis remains poorly understood. Here, we reveal a 5' untranslated region (5'UTR)-mediated translational mechanism that controls glucosinolate production in <i>Arabidopsis</i>. A forward genetic screen exploring the metabolic interaction between auxin and glucosinolates identified two dominant <i>Arabidopsis</i> alleles, each carrying a single-nucleotide substitution located 13-base pair apart within the 5'UTR of <i>MYB28</i>, a master regulator of aliphatic glucosinolate biosynthesis. These mutations markedly increase MYB28 protein abundance without affecting transcript levels, leading to enhanced glucosinolate production. Mutational profiling of the 5'UTR revealed that alterations in RNA tertiary structure influence translation efficiency, establishing a link between RNA conformation and metabolic output. Our findings uncover a previously uncharacterized layer of posttranscriptional regulation in plant-specialized metabolism and highlight the 5'UTR as a potential target for precision breeding to enhance crop performance and nutritional quality.