A Fusarium verticillioides MAT1-2 strain near isogenic to the sequenced FGSC7600 strain for producing homozygous multigene mutants

Authors: Gold, Scott; Brown, Daren; WILLIAMS, FELICIA - University Of Georgia; NADEN, BRIAN - US Department Of Agriculture (USDA); VO, VIVIAN - University Of Georgia; Miller, Christine

Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2024
Publication Date: 8/21/2024
Citation: Gold, S.E., Brown, D.W., Williams, F.N., Naden, B.D., Vo, V., Miller, C.E. 2024. A Fusarium verticillioides MAT1-2 strain near isogenic to the sequenced FGSC7600 strain for producing homozygous multigene mutants. The Journal of Fungi. 10, 592. https://doi.org/10.3390/jof10080592.
DOI: https://doi.org/10.3390/jof10080592

Interpretive Summary: Our goal was to reduce variation in sibling offspring. To do this we produced a nearly identical strain of opposite mating type to wild type. A Mat1-2 offspring from an initial mating between FGSC7603 (Mat1-2) to the standard sequenced strain FGSC7600 (Mat1-1) was selected. This was followed by six generations of crosses with FGSC7600 as the male parent. Chromosome exchange events through the generations were followed. Finally, a Mat1-2 strain with greater than 90% identity to FGSC7600 was generated. Interestingly a region containing fifty-four genes was lost through some progeny generations but recovered indicating that it was not required for growth or reproduction in culture. We stored the final strain for public access.

Technical Abstract: Fungal genetic systems ideally combine molecular tools for genome manipulation and a sexual reproduction system for informative assortment of combinations of genomic modifications. When employing the sexual cycle to generate multi-mutants, the background genotype variation of the parents may result in progeny phenotypic variation. Here, to mitigate this variation in Fusarium verticillioides, we generated a MAT1-2 strain near isogenic to the sequenced wild-type MAT1-1 strain, FGSC7600. This was accomplished by crossing FGSC7600 to the divergent wild-type MAT1-2 strain FGSC7603; followed by six sequential backcrosses (e.g., six generations) of MAT1-2 progeny to FGSC7600. We sequenced each generation and mapped recombination events. The parental cross involved 26 crossovers on 9 of the 11 chromosomes. Inheritance of complete chromosomes without crossover was frequently observed. A deletion of approximately 140 kilobases, containing 54 predicted genes on chromosome 4, occurred in generation 4 and was retained in generation 5 indicating these genes are dispensable for growth and both asexual and sexual reproduction. The final MAT1-2 strain TMRU10/35 is about 93% identical to FGSC7600. TMRU10/35 is also available from the Fungal Genetics Stock Center as FGSC27326 and from the ARS Culture Collection as NRRL64809.