COLLAPSED ABNORMAL POLLEN1 Gene Encoding the Arabinokinase-Like Protein Is Involved in Pollen Development in Rice

• Published in: Plant physiology (Bethesda) 2013-06, Vol.162 (2), p.858-871
• Main Authors: Ueda, Kenji, Yoshimura, Fumiaki, Miyao, Akio, Hirochika, Hirohiko, Nonomura, Ken-Ichi, Wabiko, Hiroetsu
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Anthers; Arabidopsis Proteins - genetics; Arabinose - metabolism; Biological and medical sciences; Cloning, Molecular; Developmental biology; Flowers - genetics; Fundamental and applied biological sciences. Psychology; Gametophytes; Gene Expression Regulation, Plant; Genes; GENES, DEVELOPMENT, AND EVOLUTION; Genetic Complementation Test; Grains; Magnoliopsida; Molecular Sequence Data; Mutation; Oryza - genetics; Oryza - growth & development; Phosphotransferases (Alcohol Group Acceptor) - genetics; Phylogeny; Plant cells; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Plants, Genetically Modified; Pollen; Pollen - genetics; Pollen - growth & development; Rice; Sequence Homology, Amino Acid; Sexual reproduction; Starches; Sugar Phosphates - metabolism; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.113.216523

We isolated a pollen-defective mutant, collapsed abnormal pollen1 (cap1), from Tos17 insertional mutant lines of rice (Oryza sativa). The cap1 heterozygous plant produced equal numbers of normal and collapsed abnormal grains. The abnormal pollen grains lacked almost all cytoplasmic materials, nuclei, and intine cell walls and did not germinate. Genetic analysis of crosses revealed that the cap1 mutation did not affect female reproduction or vegetative growth. CAP1 encodes a protein consisting of 996 amino acids that showed high similarity to Arabidopsis (Arabidopsis thaliana) L-arabinokinase, which catalyzes the conversion L-arabinose to L-arabinose 1-phosphate. A wild-type genomic DNA segment containing CAP1 restored mutants to normal pollen grains. During rice pollen development, CAP1 was preferentially expressed in anthers at the bicellular pollen stage, and the effects of the cap1 mutation were mainly detected at this stage. Based on the metabolic pathway of L-arabinose, cap1 pollen phenotype may have been caused by toxic accumulation of L-arabinose or by inhibition of cell wall metabolism due to the lack of UDP-L-arabinose derived from L-arabinose 1-phosphate. The expression pattern of CAP1 was very similar to that of another Arabidopsis homolog that showed 71% amino acid identity with CAP1. Our results suggested that CAP1 and related genes are critical for pollen development in both monocotyledonous and dicotyledonous plants.