The Role of Melanin in the Biology and Ecology of Nematophagous Fungi

Melanin is a heteropolymer formed by the polymerization of phenolic and indolic compounds. It occurs in organisms across all biological kingdoms and has a range different of functions, thus indicating its important evolutionary role. The presence of melanin offers several protective advantages, including against ultraviolet radiation, traumatic damage, oxidative stress, extreme temperatures, and pressure. For many species of fungi, melanin also participates directly in the process of virulence and pathogenicity. These organisms can synthesize melanin in two main ways: using a substrate of endogenous origin, involving 1,8-dihydroxynaphthalene (DHN); alternatively, in an exogenous manner with the addition of L-3, 4-dihydroxyphenylalanine (L-DOPA or levodopa). As melanin is an amorphous and complex substance, its study requires expensive and inaccessible technologies and analyses are often difficult to perform with conventional biochemical techniques. As such, details about its chemical structure are not yet fully understood, particularly for nematophagous fungi that remain poorly studied. Thus, this review presents an overview of the different types of melanin, with an emphasis on fungi, and discusses the role of melanin in the biology and ecology of nematophagous fungi.

Automated summary

Melanin is a heteropolymer formed by the polymerization of phenolic and indolic compounds, with various protective advantages such as against ultraviolet radiation, traumatic damage, oxidative stress, extreme temperatures, and pressure. In many fungi, melanin plays a direct role in pathogenicity, with the ability to synthesize it in different ways, either endogenously with 1,8-dihydroxynaphthalene (DHN) or exogenously with L-3, 4-dihydroxyphenylalanine (L-DOPA). The complex and amorphous nature of melanin makes it challenging to study with conventional biochemical techniques, especially in nematophagous fungi which are still poorly understood.