Dr. Hiran A. Ariyawansa is an Associate Professor in the Department of Plant Pathology and Microbiology at National Taiwan University (NTU), Taipei, where he leads a multidisciplinary lab at the interface of mycology and plant health. His research aims to explain how fungal diversity is generated and maintained, and how certain lineages transition between endophytic, saprobic, and pathogenic lifestyles. A major focus of his group is Pestalotiopsis sensu lato (including Neopestalotiopsis and Pseudopestalotiopsis), a complex of fungi that includes important emerging plant pathogens yet often shows ambiguous lifestyle behavior in nature.
The lab integrates integrative taxonomy (morphology and phylogenetics) with comparative and population genomics to link evolutionary patterns with phenotypes such as host range, virulence, and adaptation. In parallel, the group develops applied pipelines for plant disease management, including fungicide evaluation/resistance monitoring and the discovery of bacterial and fungal biocontrol agents and their inhibitory metabolites. Through research, teaching, and mentorship, Dr. Ariyawansa is committed to training students in both wet-lab experimentation and reproducible bioinformatics.

Research and Lab Introduction (detailed)

My research program sits at the intersection of fungal biodiversity, systematics, evolutionary genomics, and plant pathology, with the long-term goal of understanding how fungi diversify, shift lifestyles, and emerge as important pathogens—while also translating that knowledge into practical disease management strategies. Based at National Taiwan University (NTU), Taipei, my lab integrates field-based discovery, polyphasic taxonomy, and multi-omics approaches (comparative genomics, population genomics, transcriptomics, and metabolomics) to resolve species boundaries, infer evolutionary processes, and identify the genetic and biochemical mechanisms that underpin pathogenicity, host range, and ecological transitions.

1) Core theme: Hidden fungal diversity and accurate taxonomy as the foundation

A major pillar of our work is documenting and revising the “hidden” diversity of fungi—especially within taxonomically complex groups that contain endophytes, saprobes, and plant pathogens. We apply integrative systematics (morphology + multi-locus phylogenetics + genome-scale data when needed) to:

delimit species boundaries in difficult complexes,

stabilize names and classifications,

and build robust phylogenetic frameworks that can be used by both biodiversity scientists and plant pathologists.

This foundation is essential because misidentification and unresolved species limits can directly distort conclusions about host specificity, virulence, geographic distributions, and disease risk.

2) Core theme: Lifestyle transitions and the “genome–phenotype paradox”

Many fungi appear to shift between lifestyles—e.g., behaving as endophytes, saprobes, or pathogens depending on environment and host context. A repeated challenge we address is the observation that strikingly different field phenotypes can occur without obvious, large-scale genomic differences. Our lab investigates this “genome–phenotype paradox” by asking:

If virulence-associated gene inventories are similar, what actually drives differences in virulence and disease outcomes?

Are shifts driven by regulation, secondary metabolism, secreted enzymes, small genetic changes, or host/environment interactions?

Can we identify reproducible genomic or functional signatures that predict lifestyle expression?

This theme is central to our work on Pestalotiopsis sensu lato (including Neopestalotiopsis and Pseudopestalotiopsis) and related plant-associated fungi, where classical labels like “endophyte” versus “pathogen” often fail to capture biological reality.

3) Core theme: Emerging plant diseases and mechanisms of virulence

We study emerging and economically relevant plant diseases in Taiwan and in broader regional contexts. Our approach combines pathogen discovery and characterization with mechanism-focused experiments. Across projects, we investigate:

variation in virulence among closely related species or strains,

infection biology and host specificity,

fungicide sensitivity and resistance risk,

and candidate mechanisms involving secretomes, CAZymes, effectors, signaling pathways, and secondary metabolite biosynthetic gene clusters (BGCs).

Rather than relying on a single data type, we prioritize convergent evidence: infection assays and phenotyping supported by genomic comparisons, gene-expression patterns, metabolite profiling, and targeted functional tests.

4) Biocontrol and reduced-pesticide disease management

A translational arm of the lab focuses on biological control agents (BCAs) and strategies to reduce pesticide inputs while maintaining disease suppression. We evaluate bacterial and fungal antagonists (e.g., promising isolates showing inhibition through volatile and non-volatile metabolites) and work to understand:

how biocontrol candidates suppress pathogens (growth inhibition, VOCs, antibiosis, induced resistance, competition),

which metabolites are responsible,

and how plant or pathogen gene expression responds during interactions.

We also explore the ecology of beneficial microbes (e.g., Trichoderma diversity in agroecosystems) to identify strains with strong potential for field deployment and to develop evidence-based application strategies.

5) Platforms and lab strengths: from field to genome to function

The lab is built to connect real-world disease problems to mechanistic insight. Key capabilities include:

Field sampling and culture-based work

disease surveys and targeted sampling across hosts and environments

isolation, purification, and preservation of fungal and bacterial strains

classical characterization and experimental designs that support reproducible phenotyping

Molecular systematics and phylogenomics

multi-gene phylogenetics and species delimitation

genome-based comparisons (ANI, orthogroups, pan-genomes)

evolutionary inference across clades and complexes

Comparative genomics and population genomics

genome assembly/annotation workflows

analysis of secretomes, CAZymes, effectors, BGCs, transposable elements, and gene-family evolution

SNP-based population structure and genotype–phenotype association strategies when datasets allow

Functional and chemical ecology assays

pathogenicity and cross-infection assays with quantitative scoring

enzyme activity and physiology assays (including carbon-use profiling where relevant)

metabolite-focused approaches to link inhibitory activity to candidate compounds

6) Training philosophy and lab culture

We train students to be bilingual in biology and computation: capable in wet-lab fundamentals (isolation, culturing, pathogenicity testing, assay design) and confident in modern bioinformatics (genome comparisons, phylogenomics, reproducible analysis). Students learn how to:

frame strong hypotheses,

choose methods that directly test them,

and communicate outcomes clearly in manuscripts, presentations, and datasets that others can reuse.

Our projects are designed to yield both fundamental discoveries (new taxa, evolutionary patterns, mechanism insights) and applied outputs (diagnostic clarity, risk assessment, fungicide guidance, and biocontrol options).

7) Impact and direction

By combining taxonomy with genomics and functional validation, our lab aims to deliver a more predictive understanding of fungal biology: which lineages are likely to become problematic pathogens, how virulence evolves without major gene-content shifts, and how we can manage diseases more sustainably using integrated strategies. Ultimately, we view biodiversity research and plant pathology not as separate disciplines, but as mutually reinforcing—accurate species concepts and evolutionary insight are the fastest route to durable, science-driven disease management.