Clustering of Two Genes Putatively Involved in Cyanate Detoxification Evolved Recently and Independently in Multiple Fungal Lineages

horngren, chales t. ...... [et.all];

Fungi that have the enzymes cyanase and carbonican hydrase show a limited capacity to detoxify cyanate, a fungicide employed by both plants and humans. Here, we describe a novel two-gene cluster that comprises duplicated cyanase and carbonic anhydrase copies, which we name the CCA genecluster, trace it sevolution across As comycetes, and examine the evolutionary dynamics of its spread among lineages of the Fusarium oxysporum species complex (hereafter referred to as the FOSC), a cosmopolitan clade of purportedly clonalvascular wilt plant pathogens. Phylogenetic analysis off ungalcy anase and carbonican hydrase genes reveals that the CCA gene clusterarose independently atleast twice and is now present in three lineages, namely Cochlioboluslunatus, Oidiodendron maius,and the FOSC. Genome-wide surveys within the FOSC indicate that the CCA gene cluster varies in copy number across isolates, is always located on accessory chromosomes, and is absent in FOSC’s closest relatives. Phylogenetic reconstruction of the CCA gene cluster in 163FOSC strains from a wide variety of hosts suggests are cent history of rampant transfers between isolates. We hypothesize that the independent formation of the CCA gene cluster in different fungal lineages and its spread across FOSC strains may be associated with resistance to plant-produced cyanates or touse of cyanate fungicide sin agriculture