Plants self-synthesize “agrochemical” to fight pests and diseases

In this article, we present recent findings from a Nature Chemical Biology paper that elucidate the mechanism of crucial biosynthetic steps involved in the synthesis of steroidal glycoalkaloids (SGAs), an important defense substance in a variety of Solanum plants. The enzyme GAME12, identified in Solanum lycopersicum, has evolved from the ancestral GABA enzyme through gene duplication events. Notably, GAME12 has acquired a neofunctional capability, undergoing modifications in both active site specificity and subcellular localization. This shift allows for a transition from its foundational role in core metabolism to its involvement in specialized metabolic pathways. The distinctive function of transamination enables the incorporation of nitrogen atoms into the backbones of steroidal specialized metabolites during the later stages of SGA biosynthesis, resulting in the production of nitrogen-containing antinutrients. This research underscores the significance of hijacking shunt enzymes from core metabolic pathways to facilitate the biosynthesis of nitrogen-containing steroidal glycoalkaloids, thereby enhancing the defensive mechanisms of Solanum species against pests and diseases.