Table 1.

Functional roles of meiotic genes searched in the diatom genomes

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]
Zip2a,Zip3/Hei10a, Zip4a	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]

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