The putative Arabidopsis homolog of yeast vps52p is required for pollen tube elongation, localizes to Golgi, and might be involved in vesicle trafficking.
The screening of the Versailles collection of Arabidopsis T-DNA transformants allowed us to identify several male gametophytic mutants, including poky pollen tube (pok). The pok mutant, which could only be isolated as a hemizygous line, exhibits very short pollen tubes, explaining the male-specific transmission defect observed in this line. We show that the POK gene is duplicated in the Arabidopsis genome and that the predicted POK protein sequence is highly conserved from lower to higher eukaryotes. The putative POK homolog in yeast (Saccharomyces cerevisiae), referred to as Vps52p/SAC2, has been shown to be located at the late Golgi and to function in a complex with other proteins, Vps53p, Vps54p, and Vps51p. This complex is involved in retrograde trafficking of vesicles between the early endosomal compartment and the trans-Golgi network. We present the expression patterns of the POK gene and its duplicate P2 in Arabidopsis, and of the putative Arabidopsis homologs of VPS53 and VPS54 of yeast. We show that a POK::GFP fusion protein localizes to Golgi in plant cells, supporting the possibility of a conserved function for Vps52p and POK proteins. These results, together with the expression pattern of the POK::GUS fusion and the lack of plants homozygous for the pok mutation, suggest a more general role for POK in polar growth beyond the pollen tube elongation process.
Lobstein
Eglantine
E
Institut National de la Recherche Agronomique, Station de Génétique et d'Amélioration des Plantes, Institut Jean-Pierre Bourgin, Centre de Versailles-Grignon, 78026 Versailles cedex, France.
Guyon
Anouchka
A
Férault
Madina
M
Twell
David
D
Pelletier
Georges
G
Bonhomme
Sandrine
S
D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D006056:Golgi Apparatus / Q000502:physiology* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D011058:Pollen / Q000254:growth & development; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics
D029681:Arabidopsis Proteins; D017931:DNA Primers; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C093602:VPS52 protein, S cerevisiae