Gsp1 triggers the sexual developmental program including inheritance of chloroplast DNA and mitochondrial DNA in Chlamydomonas reinhardtii.
The isogamous green alga Chlamydomonas reinhardtii has emerged as a premier model for studying the genetic regulation of fertilization and sexual development. A key regulator is known to be a homeoprotein gene, GAMETE-SPECIFIC PLUS1 (GSP1), which triggers the zygotic program. In this study, we isolated a mutant, biparental31 (bp31), which lacks GSP1. bp31 mt+ gametes fuse normally to form zygotes, but the sexual development of the resulting diploid cell is arrested and pellicle/zygospore/tetrad formation is abolished. The uniparental inheritance of chloroplast (cp) and mitochondrial (mt) DNA (cytoplasmic inheritance) was also impaired. bp31 has a deletion of ∼60 kb on chromosome 2, including GSP1. The mutant phenotype was not rescued by transformation with GSP1 alone but could be rescued by the cotransformation with GSP1 and another gene, INOSITOL MONOPHOSPHATASE-LIKE1, which is involved in various cellular processes, including the phosphatidylinositol signaling pathway. This study confirms the importance of Gsp1 in mediating the zygotic program, including the uniparental inheritance of cp/mtDNA. Moreover, the results also suggest a role for inositol metabolism in the sexual developmental program.
Laboratory of Plant Molecular Genetics, Department of Botany, Kyoto University, Oiwake-cho, Kita-Shirakawa, Kyoto 606-8502, Japan. yoshiki@pmg.bot.kyoto-u.ac.jp
Yoshiki
Y
Nishimura
Toshiharu
T
Shikanai
Soichi
S
Nakamura
Maki
M
Kawai-Yamada
Hirofumi
H
Uchimiya
D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000254:growth & development; D018742:DNA, Chloroplast / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005111:Extrachromosomal Inheritance; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion; D015053:Zygote / Q000254:growth & development*
D018742:DNA, Chloroplast; D004272:DNA, Mitochondrial; C116848:GSP1 protein, Chlamydomonas; D018398:Homeodomain Proteins; D010940:Plant Proteins