Phylogenetic and Pathogenic Characterization of Alternaria Species

Alternaria species comprise a diverse assemblage of filamentous fungi within the Pleosporaceae, notorious for causing leaf blotch, early blight and fruit spot across a wide range of crop and non-crop hosts. Recent phylogenetic studies employing multi-locus and genome-wide approaches have disentangled cryptic lineages in complexes such as Alternaria alternata and Alternaria arborescens, revealing incomplete lineage sorting, recombination and fuzzy species boundaries that defy classical morphology-based taxonomy. Parallel investigations into pathogenicity have clarified the necrotrophic lifestyle of major species, identified host-selective toxins encoded on conditionally dispensable chromosomes and uncovered evidence for both clonal propagation and cryptic sexual cycles. These integrated insights are reshaping disease forecasting, quarantine decisions and sustainable management of Alternaria-associated disorders.

Research from Nature Portfolio

Recent work has challenged the view of Alternaria as a primary pathogen in apple orchards by demonstrating its role as a necrosis-dependent opportunist. Three-year field trials without fungicidal inputs showed that targeted leaf fertilisation—raising magnesium, sulphur and manganese levels—reduced blotch symptoms by over 70%, matching the efficacy of standard fungicides and underscoring a shift towards agronomic rather than chemical control. Complementary population genetic surveys of Alternaria alternata, A. linariae and A. solani isolates from tomato and potato in North Carolina and Wisconsin have revealed unexpectedly high genotypic diversity, balanced mating-type frequencies and signs of recombination. These findings overturn the assumption of strict clonality and suggest that adaptive evolution may be driven by occasional sexual cycles.

Phylogenetic and Pathogenic Characterization of Alternaria Species publication trend

The graph below shows the total number of articles in phylogenetic and pathogenic characterization of alternaria species across all publications each year (not limited to Nature Index journals).

Technical terms

Multi-locus sequence typing (MLST): A method for characterising strains by sequencing multiple unlinked genetic loci to infer phylogenetic relationships.

Necrotrophic pathogen: A microorganism that kills host tissue and derives nutrients from the dead cells.

Host-selective toxin (HST): A specialised metabolite produced by some pathogens that targets specific host species to facilitate infection.

Conditionally dispensable chromosome (CDC): A nonessential chromosome carrying genes, such as those for toxins, that can enhance pathogenicity under certain conditions.

Recombination: The exchange of genetic material between different strains or lineages, contributing to genetic diversity and adaptation.

References

1. Alternaria diseases on potato and tomato. Molecular Plant Pathology (2024).
2. Discord between morphological and phylogenetic species boundaries: incomplete lineage sorting and recombination results in fuzzy species boundaries in an asexual fungal pathogen. BMC Ecology and Evolution (2014).
3. Population genetic analysis reveals cryptic sex in the phytopathogenic fungus Alternaria alternata. Scientific Reports (2015).
4. Phylogenomic analyses of Alternaria section Alternaria: A high-resolution, genome-wide study of lineage sorting and gene tree discordance. Mycologia (2021).
5. Genetic diversity and population structure of Alternaria species from tomato and potato in North Carolina and Wisconsin. Scientific Reports (2021).
6. Fungicide-free management of Alternaria leaf blotch and fruit spot on apple indicates Alternaria spp. as secondary colonizer. Scientific Reports (2023).
7. Species diversity and molecular characterization of Alternaria section Alternaria isolates collected mainly from cereal crops in Canada. Frontiers in Microbiology (2023).
8. Alternaria arborescens and A. italica Causing Leaf Blotch on Celtis julianae in China. Plants (2023).