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Exploring the genome of Metschnikowia fructicola, a biocontrol yeast effective against postharvest diseases

Maria Lodovica Gullino: Agroinnova - University of Torino

<div>The yeast <em>Metschnikowia fructicola</em> has been reported as an efficient biocontrol agent of postharvest diseases of fruit. The mechanisms of action by which <em>M. fructicola</em> inhibits postharvest pathogensinclude iron-binding compounds, induction of defence signalling genes, such as PRP and MAPK cascade genes, production of fungal cell wall degrading enzymes and relatively high amounts of superoxide anions. <em>M. fructicola </em>also exhibits chitinase activity and the chitinase gene, <em>MfChi,</em> was highly induced in response to fungal pathogen cell walls. Several studies have examined differential gene expression during the interaction of the yeast, <em>M. fructicola</em>, with a host fruit or a postharvest pathogen. In the current work, we report the assembly of the whole genome sequence of two strains of <em>M. fructicola</em> using PacBio and Illumina shotgun sequencing technologies. Using the PacBio, a high-quality draft genome consisting of 93 scaffolds, with an estimated genome size of approximately 26 Mb, was obtained. Comparative analysis of <em>M. fructicola</em> proteins with three available closely-related genomes revealed a shared core of homologous proteins. Comparing the genomes of the two <em>M. fructicola</em> strains using a SNP calling approach resulted in the identification of 564,302 SNPs/indels with a total of 2,004 predicted high impact mutations. Based on the assembled genome, sequences were annotated with gene description and gene ontology and clustered in functional groups. Analysis of CAZyme family genes revealed 1,145 putative genes. Transcriptomic analysis of CAZymes in <em>M. fructicola</em> during its interaction with either grapefruit peel tissue or <em>Penicillium digitatum</em> revealed a high level of CAZyme gene expression when the yeast was placed in wounded fruit tissue. The significance of the findings in biocontrol capabilities of <em>M. fructicola</em> will be discussed.</div>

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