title: Molecular characterization of the glauce mutant: a central cell-specific function is required for double fertilization in Arabidopsis.
abstract: Double fertilization of the egg cell and the central cell by two sperm cells, resulting in the formation of the embryo and the endosperm, respectively, is a defining characteristic of flowering plants. The Arabidopsis thaliana female gametophytic mutant glauce (glc) can exhibit embryo development without any endosperm. Here, we show that in glc mutant embryo sacs one sperm cell successfully fuses with the egg cell but the second sperm cell fails to fuse with the central cell, resulting in single fertilization. Complementation studies using genes from the glc deletion interval identified an unusual genomic locus having homology to BAHD (for BEAT, AHCT, HCBT, and DAT) acyl-transferases with dual transcription units and alternative splicing that could rescue the sterility defect of glc. Expression of these transcripts appears restricted to the central cell, and expression within the central cell is sufficient to restore fertility. We conclude that the central cell actively promotes its own fertilization by the sperm cell through a signaling mechanism involving products of At1g65450. Successful fertilization of the egg cell is not blocked in the glc mutant, suggesting that evolution of double fertilization in flowering plants involved acquisition of specific functions by the central cell to enable its role as a second female gamete.
authors.affiliation: Department of Plant Biology, University of California, Davis, California 95616, USA.
authors.forename: Yehoram
authors.initials: Y
authors.lastname: Leshem
authors.forename: Cameron
authors.initials: C
authors.lastname: Johnson
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Wuest
authors.forename: Xiaoya
authors.initials: X
authors.lastname: Song
authors.forename: Quy A
authors.initials: QA
authors.lastname: Ngo
authors.forename: Ueli
authors.initials: U
authors.lastname: Grossniklaus
authors.forename: Venkatesan
authors.initials: V
authors.lastname: Sundaresan
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D056625:Endosperm / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D005306:Fertilization; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D056426:Genetic Loci; D055993:Germ Cells, Plant / Q000166:cytology / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D012639:Seeds / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome
chemical_list: D029681:Arabidopsis Proteins; D049452:Green Fluorescent Proteins; D000217:Acyltransferases