AUTHOR=Tiley Anna M. M. , Foster Gary D. , Bailey Andy M. 

TITLE=Exploring the Genetic Regulation of Asexual Sporulation in Zymoseptoria tritici

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01859

DOI=10.3389/fmicb.2018.01859

ISSN=1664-302X

ABSTRACT=<p><italic>Zymoseptoria tritici</italic> is the causal agent of septoria tritici blotch, a devastating fungal disease of wheat which can cause up to 40% yield loss. One of the ways in which <italic>Z. tritici</italic> spreads in the field is via rain splash-dispersed asexual pycnidiospores, however there is currently limited understanding of the genetic mechanisms governing the development of these propagules. In order to explore whether the existing models for conidiation in ascomycete fungi apply to <italic>Z. tritici</italic>, homologs to the well-characterized <italic>Aspergillus nidulans</italic> genes <italic>abacus</italic> (<italic>abaA</italic>)<italic>, bristle</italic> (<italic>brlA</italic>)<italic>, fluffy B</italic> (<italic>flbB</italic>), <italic>fluffy C</italic> (<italic>flbC</italic>), and <italic>stunted</italic> (<italic>stuA</italic>) were identified and knocked-out by <italic>Agrobacterium</italic>-mediated transformation. Although deletion of the <italic>ZtAbaA, ZtBrlA1</italic>, and <italic>ZtFlbB</italic> genes had no apparent effect on <italic>Z. tritici</italic> asexual sporulation or on pathogenicity, deletion of <italic>ZtFlbC</italic> or <italic>ZtBrlA2</italic> resulted in mutants with reduced pycnidiospore production compared to the parental IPO323 strain. Deletion of <italic>ZtStuA</italic> gave non-pigmented mutants with altered vegetative growth and eliminated asexual sporulation and pathogenicity. These findings suggest that the well-established <italic>A. nidulans</italic> model of asexual sporulation is only partially applicable to <italic>Z. tritici</italic>, and that this pathogen likely uses additional, as yet uncharacterized genes to control asexual sporulation.</p>