Phytotoxic metabolites produced by legume-associated Ascochyta and its related genera in the Dothideomycetes

Authors: KIM, WONYONG - Suncheon National University; Chen, Weidong

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2019
Publication Date: 10/29/2019
Citation: Kim, W., Chen, W. 2019. Phytotoxic metabolites produced by legume-associated Ascochyta and its related genera in the Dothideomycetes. Toxins. 11(11). Article 627. https://doi.org/10.3390/toxins11110627.
DOI: https://doi.org/10.3390/toxins11110627

Interpretive Summary: Fungal pathogens are a important group of pathogens causing diseases on grain legumes. The pathogens produce many secondary metabolites and the metabolites are often toxic to plants hence termed phytotoxins. Phytotoxins are thought to play important roles in necrotrophic disease development. An example is the group of Ascochyta and related taxa like Phoma that cause Ascochyta blights of cool season grain legumes (pea, chickpea, lentil and faba bean), and they are often associated with specific legume plants, showing relatively narrow host range. The legume-associated Ascochyta and Phoma produce diverse array of polyketide-derived secondary metabolites, many of which exhibited significant toxicity to plants and by association have been claimed, without rigorous proof, as virulence or pathogenicity factors. This article presents the current state of knowledge on diversity and biological activities of the phytotoxic compounds produced by Ascochyta and Phoma species, as well as gene clusters responsible for the secondary metabolite biosynthesis and the role of metabolites in the fungal biology.

Technical Abstract: Phytotoxins have been believed to play an important role in disease development in plant pathogenic fungi by targeting host cellular machineries and/or interfering with host immune responses. The Ascochyta blight diseases on different legume plants are caused by Ascochyta and related taxa, such as Phoma. The causal agents of the Ascochyta blight are often associated with specific legume plants, showing relatively narrow host range. The legume-associated Ascochyta and Phoma are known to produce diverse array of polyketide-derived secondary metabolites, many of which exhibited significant phytotoxicity and have been claimed as virulence or pathogenicity factor. In this article, we reviewed the current state of knowledge on diversity and biological activities of the phytotoxic compounds produced by Ascochyta and Phoma species. Also, we touched on secondary metabolite biosynthesis gene clusters identified thus far and discussed the role of metabolites in the fungal biology.