Multilocus molecular phylogenetic-led discovery and formal recognition of four novel root-colonizing <i>Fusarium</i> species from northern Kazakhstan and the phylogenetically divergent <i>Fusarium steppicola</i> lineage

In this study, DNA sequence data were used to characterize 290 <i>Fusarium</i> strains isolated during a survey of root-colonizing endophytic fungi of agricultural and nonagricultural plants in northern Kazakhstan. The <i>Fusarium</i> collection was screened for species identity using partial translation elongation factor 1-α (<i>TEF1</i>) gene sequences. Altogether, 16 different <i>Fusarium</i> species were identified, including eight known and four novel species, as well as the discovery of the phylogenetically divergent <i>F. steppicola</i> lineage. Isolates of the four putatively novel fusaria were further analyzed phylogenetically with a multilocus data set comprising partial sequences of <i>TEF1</i>, RNA polymerase II largest (<i>RPB1</i>) and second-largest (<i>RPB2</i>) subunits, and calmodulin (<i>CaM</i>) to assess their genealogical exclusivity. Based on the molecular phylogenetic and comprehensive morphological analyses, four new species are formally described herein: <i>F. campestre, F. kazakhstanicum, F. rhizicola</i>, and <i>F. steppicola</i>.