title: Sequence of the Gonium pectorale Mating Locus Reveals a Complex and Dynamic History of Changes in Volvocine Algal Mating Haplotypes.
abstract: Sex-determining regions (SDRs) or mating-type (MT) loci in two sequenced volvocine algal species, Chlamydomonas reinhardtii and Volvox carteri, exhibit major differences in size, structure, gene content, and gametolog differentiation. Understanding the origin of these differences requires investigation of MT loci from related species. Here, we determined the sequences of the minus and plus MT haplotypes of the isogamous 16-celled volvocine alga, Gonium pectorale, which is more closely related to the multicellular V. carteri than to C. reinhardtii Compared to C. reinhardtii MT, G. pectorale MT is moderately larger in size, and has a less complex structure, with only two major syntenic blocs of collinear gametologs. However, the gametolog content of G. pectorale MT has more overlap with that of V. carteri MT than with C. reinhardtii MT, while the allelic divergence between gametologs in G. pectorale is even lower than that in C. reinhardtii Three key sex-related genes are conserved in G. pectorale MT: GpMID and GpMTD1 in MT-, and GpFUS1 in MT+. GpFUS1 protein exhibited specific localization at the plus-gametic mating structure, indicating a conserved function in fertilization. Our results suggest that the G. pectorale-V. carteri common ancestral MT experienced at least one major reformation after the split from C. reinhardtii, and that the V. carteri ancestral MT underwent a subsequent expansion and loss of recombination after the divergence from G. pectorale These data begin to polarize important changes that occurred in volvocine MT loci, and highlight the potential for discontinuous and dynamic evolution in SDRs.
authors.affiliation: Donald Danforth Plant Science Center, St Louis, Missouri 63132 thamaji@danforthcenter.org.
authors.forename: Takashi
authors.identifier: 0000-0002-2801-2148
authors.initials: T
authors.lastname: Hamaji
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo 113-0033, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Mogi
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Ferris
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo 113-0033, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Mori
authors.affiliation: Symbiosis and Cell Evolution Laboratory and Comparative Genomics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Miyagishima
authors.affiliation: Symbiosis and Cell Evolution Laboratory and Comparative Genomics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.
authors.forename: Yukihiro
authors.identifier: 0000-0001-6328-0765
authors.initials: Y
authors.lastname: Kabeya
authors.affiliation: Symbiosis and Cell Evolution Laboratory and Comparative Genomics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Nishimura
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyoda
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Noguchi
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Asao
authors.initials: A
authors.lastname: Fujiyama
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas 66506.
authors.forename: Bradley J S C
authors.initials: BJ
authors.lastname: Olson
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas 66506.
authors.forename: Tara N
authors.initials: TN
authors.lastname: Marriage
authors.affiliation: Department of Chemistry, Biology, and Environmental Sciences, Faculty of Science, Nara Women's University, Nara 630-8506, Japan.
authors.forename: Ichiro
authors.identifier: 0000-0003-0045-1525
authors.initials: I
authors.lastname: Nishii
authors.affiliation: Donald Danforth Plant Science Center, St Louis, Missouri 63132.
authors.forename: James G
authors.identifier: 0000-0003-4094-9045
authors.initials: JG
authors.lastname: Umen
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo 113-0033, Japan.
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Nozaki
mesh_terms: D016386:Chromosome Walking; D019295:Computational Biology; D019143:Evolution, Molecular; D015870:Gene Expression; D008040:Genetic Linkage; D018745:Genome, Plant; D023281:Genomics / Q000379:methods; D006239:Haplotypes; D059014:High-Throughput Nucleotide Sequencing; D010802:Phylogeny; D040641:Quantitative Trait Loci; D012098:Reproduction / Q000235:genetics*; D019849:Sex Determination Processes / Q000235:genetics; D044446:Volvox / Q000145:classification / Q000235:genetics*
keywords: Chlamydomonas; Genetics of Sex; Gonium; Volvox; evolution; mating locus