Hybridization between Japanese and North American Chlamydomonas reinhardtii (Volvocales, Chlorophyceae)

Abstract

Summary The microalga Chlamydomonas reinhardtii is a model organism whose whole genome has been sequenced. Although considered a cosmopolitan species, only eastern North American isolates of C. reinhardtii were available before 2010, when new Japanese isolates were reported. In the study describing the new Japanese isolates, zygote formation between Japanese and North American strains was shown, but germination was not demonstrated. In this study, the germination of intercontinental hybrid zygotes was examined using wild‐type Japanese strains and mutant American strains that cannot utilize nitrate. Several clonal progeny strains were established, and the progeny strains were screened based on mating type and nitrate utilization to confirm their hybrid nature. The establishment of four intercontinental hybrid strains with different phenotypic combinations was confirmed by sequencing mating type‐specific and nitrate reductase‐related genes. The potential for hybrid formation between Japanese and North American strains suggests the existence of a worldwide mating population of C. reinhardtii.

Taxonomic revision of Chlamydomonas subg. Amphichloris (Volvocales, Chlorophyceae), with resurrection of the genus Dangeardinia and descriptions of Ixipapillifera gen. nov. and Rhysamphichloris gen. nov.

“…, Nakada and Nozaki , Nakada et al. ,c, ). Therefore, R. similis and R. curta are treated here as an independent species.…”

Whole-Genome Resequencing Reveals Extensive Natural Variation in the Model Green Alga Chlamydomonas reinhardtii

“…At present there are too few environmental isolates of Chlamydomonas to conduct genomewide association studies, which have spurred recent developments in many areas of crop research. This highlights the importance of continued efforts to isolate new strains of Chlamydomonas (Nakada et al, 2014). Although conventional breeding and selection for desirable traits in Chlamydomonas and other algae, particularly for biofuel production, may progress slowly (Bonente et al, 2011), studies of natural isolates offer a potentially large and untapped reservoir of variation in heterogeneous genetic backgrounds that can be exploited in studies of gene function, quantitative trait loci studies, and targeted selection experiments.…”

“…Chlamydomonas is a heterothallic species that persists as a haploid that is one of two distinct mating types (mt+ or mt2) during the vegetative stage of its life cycle. Reproductively compatible strains have been isolated from freshwater and moist soils in North America and Japan (Nakada et al, 2014) and can switch between photoautotrophic and mixotrophic strategies when provided with a suitable carbon source. In addition, practical characteristics such as the ease with which it can be cultured, the ability to conduct conventional genetic crosses, and the relative simplicity of genetic manipulation make Chlamydomonas a preferred alga for experimental studies (Graham, 1997;Harris, 2008).…”

Flagellate Green Algae

“…Pandorina morum contains more than 20 sexually isolated groups (syngens) distributed throughout the world (Coleman, 1959(Coleman, , 1977, and their genetic differences are large (Coleman et al, 1994). Although possible endemism in North America was indicated in a colonial genus Platydorina and a unicellular species Chlamydomonas reinhardtii in the past (Kofoid, 1899;Harris and Starr, 1969;Ortega, 1984;Nozaki, 2003;, these taxa have been reported in Asia (Dedusenko-Shchegoleva et al, 1959;Nakada et al, 2010b;Pan et al, 2010;Hong et al, 2013;Nakada et al, 2014). Almost all of the well-studied genera of green flagellates are global in their distribution .…”