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Table 1 Functional roles of meiotic genes searched in the diatom genomes

From: Identification of the meiotic toolkit in diatoms and exploration of meiosis-specific SPO11 and RAD51 homologs in the sexual species Pseudo-nitzschia multistriata and Seminavis robusta

Protein Role in meiosis
DNA replication and chromosome maintenance
 Mcm2-7 Mcm2-7 form hexamer and are involved in DNA replication [28]
 Mcm8 Mcm8 and Mcm9 are involved in meiotic recombination [81, 83, 84]
 Mcm9 Mcm8 and Mcm9 are involved in meiotic recombination [83, 84]
 Smc1-Smc3 Part of sister chromatids cohesin subunit, act as a heterodimer
 Smc2-Smc4 Heterodimer, essential for chromosome assembly and segregation, part of core condensing subunits
 Smc5-Smc6 Heterodimer, involved in DNA repair and checkpoint response, binds to single stranded DNA (ssDNA)
 Pds5 Involved in maintenance of sister chromatid cohesion in late prophase
 Scc3 Interacts with cohesin complex Smc1-Smc3 and Rad21/Rec8 and helps in holding cohesin ring together
 Rec8/Syn1a Meiotic homolog of Rad21, involved in holding sister chromatids together during meiotic recombination
 Rad21 Holds Smc1 and Smc3 together thus holding sister chromatids together during meiosis and mitosis
DNA double strand break formation
 Spo11-1a Creates double strand breaks (DSBs) in homologous chromosomes in meiotic recombination
 Spo11-2a Creates DSBs in homologous chromosomes in meiotic recombination in plants
 Spo11-3/Top VIA Required for endoreduplication of DNA
DNA damage sensing and response
 Rad50 DNA binding ATPase, holds broken DNA strands while Mre11 trims DSBs
 Mre11 3′–5′ dsDNA exonuclease and ssDNA endonuclease; trims 
broken DNA ends after DSBs and hairpins
 Xrs2/Nbs1 Component of Mre11-Rad50-Xrs2, involved in homologous recombination and non-homologous end joining [125]
Crossover regulation
 Mer3a DNA helicase that unwinds double stranded DNA during meiotic cross over formation [126]
 Hop1a Binds to DSBs, component of lateral and axial synaptonemal complex
 Red1/Asy3a Component of synaptonemal complex, interacts with Hop1 and facilitates meiosis I chromosome disjunction [48, 49]
 Zip1/Zyp1a Transverse filament protein involved in synaptonemal complex formation during meiosis [45, 47]
Components of synaptonemal complex required for morphogenesis of the synaptonemal complex [45, 64]
 Dmc1a Meiotic member of Rad51-RadA-RecA superfamily of proteins, binds to ssDNA end of DSBs and is involved in inter-homologous recombination
 Hop2a Homology search together with Mnd1, works in Dmc1 dependent homology search pathway downstream of Rad51
 Mnd1a Together with Hop2 works in homology searching and is also required in stable DNA heteroduplex
 Msh4a-Msh5a Heterodimer, together with Mlh1/Mhl3 heterodimer directs Holliday junction resolution with crossover interference
Double-strand break repair (recombinational repair)
 Rad51, Xrcc2, Xrcc3 Mediate homologous pairing and strand invasion, involved in DNA repair mechanisms in mitosis and meiosis. Part of Rad51-RadA-RecA superfamily, exhibit multiple paralogs
 Rad52 Binds to ssDNA and initiates homologous recombination, stimulates Rad51 mediated strand invasion
 Rad1 5′-3′ endonuclease, required in meiotic crossing over, functions during nucleotide excision repair
 Msh2 Forms heterodimer with Msh3 or Msh6, works in DNA mismatch repair
 Msh6 Forms heterodimer with Msh2, works in DNA mismatch repair
 Mlh1 DNA mismatch repair protein, forms heterodimers with Mlh2, Mlh3 and Pms1, interacts with Msh2/Msh6 and Msh4/Msh5
 Mlh2 DNA mismatch repair protein, forms heterodimer with Mlh1
 Mlh3 Forms heterodimer with Mlh1, interacts with Msh4/Msh5 to promote meiotic crossovers
 Pms1 Forms heterodimer with Mlh1, involved in DNA mismatch repair
 Mms4/Eme1 Interacts with Mus81 and is involved in interference insensitive, class II crossovers during meiotic recombination [104]
 Mus81 Interacts with Mms4 and is involved in interference insensitive, class II crossovers during meiotic recombination [104]
 Fancm DNA helicase required for genome stability, involved in limiting meiotic crossovers [127]
Other accessory proteins required during meiosis
 Fen1 Fen1 functions during homologous recombination mediated DNA repair by removing divergent sequences at DNA break ends [128]
 Exo1 A double-stranded DNA-specific 5′–3′ exonuclease [129]
 Dna2 A conserved DNA nuclease involved in DNA stability [130]
 Brca1 Regulates meiotic spindle assembly [131]
 Brca2 Involved in DNA damage-induced Rad51 foci formation during meiosis [132]
  1. Gene functions are taken from Malik et al. [6] and from Hanson et al. [33] unless otherwise mentioned. Genes marked with a are considered meiosis-specific genes and do not have known functions outside of meiosis