Microspore separation in the quartet 3 mutants of Arabidopsis is impaired by a defect in a developmentally regulated polygalacturonase required for pollen mother cell wall degradation

• Published in: Plant physiology (Bethesda) 2003-11, Vol.133 (3), p.1170-1180
• Main Authors: Rhee, S.Y, Osbourne, E, Poindexter, P.D, Somerville, C.R
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Antibodies; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; auartet3 gene; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; Cell Wall - metabolism; Cell walls; Complementary DNA; DNA; enzyme activity; Enzymes; Escherichia coli; Fundamental and applied biological sciences. Psychology; gene expression; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genetic Complementation Test; Immunohistochemistry; messenger RNA; Microscopy, Electron, Scanning; Microspores; molecular cloning; Molecular Sequence Data; Mother cells; mutants; Mutation; nucleotide sequences; peaches; phenotype; plant development; plant morphology; Plant physiology and development; plant proteins; Plants; Pollen; Pollen - enzymology; Pollen - genetics; Pollen - ultrastructure; polygalacturonase; Polygalacturonase - genetics; Polygalacturonase - metabolism; Proteins; Prunus - enzymology; Prunus - genetics; Prunus persica; recombinant proteins; Saccharomyces cerevisiae; Sequence Homology, Amino Acid; Sexual reproduction; signal peptide; tissue distribution; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.103.028266

Mutations in the QUARTET loci in Arabidopsis result in failure of microspore separation during pollen development due to a defect in degradation of the pollen mother cell wall during late stages of pollen development. Mutations in a new locus required for microspore separation, QRT3, were isolated, and the corresponding gene was cloned by T-DNA tagging. QRT3 encodes a protein that is approximately 30% similar to an endopolygalacturonase from peach (Prunus persica). The QRT3 protein was expressed in yeast (Saccharomyces cerevisiae) and found to exhibit polygalacturonase activity. In situ hybridization experiments showed that QRT3 is specifically and transiently expressed in the tapetum during the phase when microspores separate from their meiotic siblings. Immunohistochemical localization of QRT3 indicated that the protein is secreted from tapetal cells during the early microspore stage. Thus, QRT3 plays a direct role in degrading the pollen mother cell wall during microspore development.