The Cellular and Subcellular Organization of the Glucosinolate-Myrosinase System against Herbivores and Pathogens

Glucosinolates are an important class of secondary metabolites in Brassicales plants with a critical role in chemical defense. Glucosinolates are chemically inactive but can be hydrolyzed by myrosinases to produce a range of chemically active compounds toxic to herbivores and pathogens, thereby constituting the glucosinolate-myrosinase defense system or the mustard oil bomb. During the evolution, Brassicales plants have developed not only complex biosynthetic pathways for production of a large number of glucosinolate structures but also different classes of myrosinases that differ in catalytic mechanisms and substrate specificity. Studies over the past several decades have made important progress in the understanding of the cellular and subcellular organization of the glucosinolate-myrosinase system for rapid and timely detonation of the mustard oil bomb upon tissue damage after herbivore feeding and pathogen infection. Progress has also been made in understanding the mechanisms that herbivores and pathogens have evolved to counter the mustard oil bomb. In this review, we summarize our current understanding of the function and organization of the glucosinolate-myrosinase system in Brassicales plants and discuss both the progresses and future challenges in addressing this complex defense system as an excellent model for analyzing plant chemical defense.

Automated summary

Glucosinolates are important secondary metabolites in Brassicales plants, playing a critical role in chemical defense. They are chemically inactive but can be hydrolyzed by myrosinases to produce toxic compounds, forming the glucosinolate-myrosinase defense system. Research has revealed that Brassicales plants have complex biosynthetic pathways for glucosinolate production and different classes of myrosinases with distinct catalytic mechanisms and substrate specificity. Progress has been made in understanding the cellular and subcellular organization of the glucosinolate-myrosinase system, especially in the detonation of the mustard oil bomb after tissue damage caused by herbivores and pathogens.