Metabolic gene clusters, fungal diversity, and the generation of accessory functions

Ecological interactions are largely determined by adaptive traits deemed 'accessory'. In plants, fungi, and bacteria, such traits mainly comprise metabolic pathways that produce or transform diverse molecules. While accessory metabolic pathways are pervasive, it is often difficult to identify their genetic bases. Recently, in-depth descriptions of metabolic gene clusters (MGCs), which encode discrete metabolic pathways, have greatly simplified the characterization of genotype-phenotype maps, yet questions of how this genome architecture relates to the evolution of accessory functions remain. Fungi are uniquely positioned to spearhead investigations into these dynamics because they display gradients in clustering across pathways and taxa. This review will focus on the role of MGCs as both agents and consequences of the accessory function evolution that underpins fungal diversification.