AUTHOR=Pareek Manish , Almog Yael , Bari Vinay Kumar , Hazkani-Covo Einat , Onn Itay , Covo Shay 

TITLE=Alternative Functional rad21 Paralogs in Fusarium oxysporum

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01370

DOI=10.3389/fmicb.2019.01370

ISSN=1664-302X

ABSTRACT=<p>Cohesin, the sister chromatid cohesion complex, is an essential complex that ensures faithful sister chromatid segregation in eukaryotes. It also participates in DNA repair, transcription and maintenance of chromosome structure. Mitotic cohesin is composed of Smc1, Smc3, Scc3, and Rad21/Mcd1. The meiotic cohesin complex contains Rec8, a Rad21 paralog and not Rad21 itself. Very little is known about sister chromatid cohesion in fungal plant pathogens. <italic>Fusarium oxysporum</italic> is an important fungal plant pathogen without known sexual life cycle. Here, we describe that <italic>F. oxysporum</italic> encodes for three Rad21 paralogs; Rad21, Rec8, and the first alternative Rad21 paralog in the phylum of ascomycete. This last paralog is found only in several fungal plant pathogens from the Fusarium family and thus termed <italic>rad21</italic>nc (non-conserved). Conserved <italic>rad21</italic> (<italic>rad21</italic>c), <italic>rad21</italic>nc, and <italic>rec8</italic> genes are expressed in <italic>F. oxysporum</italic> although the expression of <italic>rad21</italic>c is much higher than the other paralogs. <italic>F. oxysporum</italic> strains deleted for the <italic>rad21</italic>nc or <italic>rec8</italic> genes were analyzed for their role in fungal life cycle. Δ<italic>rad21</italic>nc and Δ<italic>rec8</italic> single mutants were proficient in sporulation, conidia germination, hyphal growth and pathogenicity under optimal growth conditions. Interestingly, Δ<italic>rad21</italic>nc and Δrec8 single mutants germinate less effectively than wild type (WT) strains under DNA replication and mitosis stresses. We provide here the first genetic analysis of alternative <italic>rad21</italic>nc and <italic>rec8</italic> paralogs in filamentous fungi. Our results suggest that <italic>rad21</italic>nc and <italic>rec8</italic> may have a unique role in cell cycle related functions of <italic>F. oxysporum</italic>.</p>