Large‐scale molecular genetic analysis in plant‐pathogenic fungi: a decade of genome‐wide functional analysis

Abstract

Plant-pathogenic fungi cause diseases to all major crop plants world-wide and threaten global food security. Underpinning fungal diseases are virulence genes facilitating plant host colonization that often marks pathogenesis and crop failures, as well as an increase in staple food prices. Fungal molecular genetics is therefore the cornerstone to the sustainable prevention of disease outbreaks. Pathogenicity studies using mutant collections provide immense function-based information regarding virulence genes of economically relevant fungi. These collections are rich in potential targets for existing and new biological control agents. They contribute to host resistance breeding against fungal pathogens and are instrumental in searching for novel resistance genes through the identification of fungal effectors. Therefore, functional analyses of mutant collections propel gene discovery and characterization, and may be incorporated into disease management strategies. In the light of these attributes, mutant collections enhance the development of practical solutions to confront modern agricultural constraints. Here, a critical review of mutant collections constructed by various laboratories during the past decade is provided. We used Magnaporthe oryzae and Fusarium graminearum studies to show how mutant screens contribute to bridge existing knowledge gaps in pathogenicity and fungal-host interactions.

Pyricularia oryzae: Lab star and field scourge

“…A description of large‐scale mutagenesis studies in the blast fungus is provided in the review article from Motaung et al. ( 2017 ). For a comprehensive listing and description of the about 400 P. oryzae genes that have been studied by mutant analysis, we recommend the very exhaustive review article of Tan et al.…”

Proteinaceous effector discovery and characterization in filamentous plant pathogens

“…Another difficulty is that such broad criteria leaves a large pool of possible effector candidates that are demanding in both time and resources to functionally characterize, with studies often having low discovery rates. The Magnaporthe grisea effector MC69, essential for appressoria formation (Motaung et al ., 2017), was the only candidate from 1,306 putative secreted proteins that was found to be required for pathogenicity following large‐scale gene disruptions (Yoshida et al ., 2009; Saitoh et al ., 2012).…”

Molecular Insights into the Pathogenicity of Necrotrophic Fungi Causing Postharvest Diseases

“…Petch, Magnaporthe oryzae B.C. Couch, and S. sclerotiorum (Motaung et al, 2017). Random plasmid integration (Baldwin et al, 2010), restriction enzyme-mediated integration (Sweigard et al, 1998), and T-DNA integration (Mullins et al, 2001) have been the main systems used to generate mutant collections.…”