Li-Jun Ma, Associate Professor
University of Massachusetts, Amherst

Topic: Fusarium pathogenomics: understanding fungal pathogenicity through genomics

Abstract: 
The ascomycete fungus Fusarium oxysporum comprises a group of well-known soil-borne plant pathogens with strong host specificity. Recently, the F. oxysporum species complex (FOSC) has become the top emerging opportunistic fungal pathogen infecting immunocompromised individuals. Distinct sets of lineage-specific (LS) chromosomes have been identified among nearly all pathogenic F. oxysporum isolates, including both plant and human pathogens. The acquisition of LS chromosomes may either introduce novel genes or paralogs of existing genes resulting in gene family expansions  in the genome. Novel genes introduced through LS chromosomes include important virulence factors, such as SIX effectors. Expanded gene families also include important key regulators, such as  kinases and transcription factors. Through comparative and functional genomics, we have found evidence of neo-functionalization as the result of expansions of some key regulator gene families. Moreover, LS chromosomes are transposon rich. The results from the experimental evolution study revealed repeated transposition events associated with hotspots for rapid evolution.  Collectively, LS chromosomes of FOSC perpetuate the functional divergence of an established network and enable the rapid adaptation of an organism when encountering novel environments, such as a new host. Such accelerated evolution occurred through enhanced environmental sensing and effective signaling regulation.  

Host Lab: Pfister