Arabidopsis CDKA;1, a cdc2 homologue, controls proliferation of generative cells in male gametogenesis

• Published in: The Plant journal : for cell and molecular biology Vol. 45; no. 5; pp. 819 - 831
• Main Authors: Iwakawa, Hidekazu, Shinmyo, Atsuhiko, Sekine, Masami
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.03.2006; Blackwell Science; Blackwell Publishing Ltd
• Subjects: Amino Acid Sequence; Arabidopsis; Arabidopsis - embryology; Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis thaliana; Biological and medical sciences; Biology and morphogenesis of the reproductive apparatus. Photoperiodism, vernalisation; CDC2 Protein Kinase; CDC2a; CDKA;1; Cell Proliferation; Cellular biology; Cyclin-Dependent Kinases - physiology; double fertilization; Enzymes; Fertilization; Flowers & plants; Fundamental and applied biological sciences. Psychology; Gametogenesis - physiology; Genes, Dominant; Genes, Plant; Genetics; male gametophyte; Mitosis; Molecular Sequence Data; Mutagenesis, Insertional; Mutation; Plant physiology and development; Pollen - growth & development; pollen mitosis II; Proteins; Sequence Homology; Vegetative and sexual reproduction, floral biology, fructification; Embryonic development; CDC2a; Seeds; Gametogenesis; Mitosis; Cell nucleus; Cell division; pollen mitosis II; EC 2.7.1.37; male gametophyte; Arabidopsis thaliana; Cruciferae; double fertilization; Dicotyledones; Angiospermae; Cell cycle; Microspore; Spermatophyta; Pollen; Mutation; CDKA;1
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2005.02643.x

Summary The protein kinase cdc2 is conserved throughout eukaryotes and acts as a key regulator of the cell cycle. In plants, A‐type cyclin‐dependent kinase (CDKA), a homologue of cdc2, has a role throughout the cell cycle. Here we show that a loss‐of‐function mutation in CDKA;1, encoding the only Arabidopsis CDKA, results in lethality of the male gametophyte. Heterozygous plants produced mature siliques containing about 50% aborted seeds, and segregation distortion was observed in paternal inheritance. Microspores normally undergo an asymmetric cell division, pollen mitosis I (PMI), to produce bicellular pollen grains. The larger vegetative cell does not divide, but the smaller generative cell undergoes mitosis, PMII, to form the two sperm cells, thereby generating tricellular pollen grains. The cdka‐1 mutant, however, produces mature bicellular pollen grains, consisting of a single sperm‐like cell and a vegetative cell, due to failure of PMII. The mutant sperm‐like cell is fertile, and preferentially fuses with the egg cell to initiate embryogenesis. As the central cell nucleus remains unfertilized, however, double fertilization does not occur. In heterozygous plants, the embryo is arrested at the globular stage, most likely because of loss of endosperm development, whereas it is arrested at the one‐ or two‐cell stage in presumptive homozygous plants. Thus, CDKA;1 is essential for cell division of the generative cell in male gametogenesis.