Welcome to the seminar "Comparative genomics of the biocontrol fungus Clonostachys rosea" by Magnus Karlsson from the Department of Forest Mycology and Plant Pathology at SLU.
The fungus Clonostachys rosea was shown to provide control of fusarium head blight and septoria tritici blotch in field trials over consecutive years, resulting in a successful patent application.
To further study the evolution and biocontrol mechanisms of this species, we performed large-scale analyses of genetic variation between species (phylogenomics) and within species (population genomics). A phylogenomic analysis of six different Clonostachys species identified several gene families evolving under selection for gene gains (P ≤ 0.05) in the ancestral lineage leading to Clonostachys, including polyketide synthases (PKS), non-ribosomal peptide syntethases (NRPS) and different membrane transporters.
Furthermore, a population genomic analysis of 63 whole-genome re-sequenced C. rosea strains revealed a primarily heterothallic mode of reproduction, contrary to the previous report of homothallism. Genome-wide association studies were then conducted to investigate the genetic architecture of various biocontrol-related traits, including in vitro antagonism against plant-parasitic nematodes. Two NRPS genes (nps4 and nps5) were present in the genomic regions associated with nematicidal activity, and gene deletion strains of nps4 and nps5 displayed reduced (P ≤ 0.05) in vitro antagonism against the root lesion nematode Pratylenchys penetrans. Gene deletion strains of nps4 and nps5 strains also showed reduced biocontrol efficacy in a naturally nematode-infested soil in a wheat pot experiment.
In summary, our comparative genomic analyses identified NRPS and various membrane transporters as targets of selection that emphasize the role of biosynthesis of, and protection against, secondary metabolites for the evolution of the Clonostachys genus.
