title: Phytosulfokine peptide signaling controls pollen tube growth and funicular pollen tube guidance in Arabidopsis thaliana.
abstract: Phytosulfokine (PSK) is a peptide growth factor that requires tyrosine sulfation carried out by tyrosylprotein sulfotransferase (TPST) for its activity. PSK is processed from precursor proteins encoded by five genes in Arabidopsis thaliana and perceived by receptor kinases encoded by two genes in Arabidopsis. pskr1-3 pskr2-1 and tpst-1 knockout mutants displayed reduced seed production, indicative of a requirement for PSK peptide signaling in sexual plant reproduction. Expression analysis revealed PSK precursor and PSK receptor gene activity in reproductive organs with strong expression of PSK2 in pollen. In support of a role for PSK signaling in pollen, in vitro pollen tube (PT) growth was enhanced by exogenously added PSK while PTs of pskr1-3 pskr2-1 and of tpst-1 were shorter. In planta, growth of wild-type pollen in pskr1-3 pskr2-1 and tpst-1 flowers appeared slower than growth in wild-type flowers. But PTs did eventually reach the base of the style, suggesting that PT elongation rate may not be responsible for the reduced fertility. Detailed analysis of anthers, style and ovules did not reveal obvious developmental defects. By contrast, a high percentage of unfertilized ovules in pskr1-3 pskr2-1 and in tpst-1 siliques displayed loss of funicular PT guidance, suggesting that PSK signaling is required to guide the PT from the transmitting tract to the embryo sac. Cross-pollination experiments with wild-type, pskr1-3 pskr2-1 and tpst-1 male and female parents revealed that both the PT and the female sporophytic tissue and/or female gametophyte contribute to successful PT guidance via PSK signaling and to fertilization success.
authors.affiliation: Plant Developmental Biology and Plant Physiology, University of Kiel, 24118, Kiel, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Stührwohldt
authors.forename: Renate I
authors.initials: RI
authors.lastname: Dahlke
authors.forename: Anke
authors.initials: A
authors.lastname: Kutschmar
authors.forename: Xiongbo
authors.initials: X
authors.lastname: Peng
authors.forename: Meng-Xiang
authors.initials: MX
authors.lastname: Sun
authors.forename: Margret
authors.initials: M
authors.lastname: Sauter
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D056771:Ovule / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D036361:Peptide Hormones / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D053205:Pollen Tube / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D054817:Pollination; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D036361:Peptide Hormones