title: PECTIN METHYLESTERASE48 is involved in Arabidopsis pollen grain germination.
abstract: Germination of pollen grains is a crucial step in plant reproduction. However, the molecular mechanisms involved remain unclear. We investigated the role of PECTIN METHYLESTERASE48 (PME48), an enzyme implicated in the remodeling of pectins in Arabidopsis (Arabidopsis thaliana) pollen. A combination of functional genomics, gene expression, in vivo and in vitro pollen germination, immunolabeling, and biochemical analyses was used on wild-type and Atpme48 mutant plants. We showed that AtPME48 is specifically expressed in the male gametophyte and is the second most expressed PME in dry and imbibed pollen grains. Pollen grains from homozygous mutant lines displayed a significant delay in imbibition and germination in vitro and in vivo. Moreover, numerous pollen grains showed two tips emerging instead of one in the wild type. Immunolabeling and Fourier transform infrared analyses showed that the degree of methylesterification of the homogalacturonan was higher in pme48-/- pollen grains. In contrast, the PME activity was lower in pme48-/-, partly due to a reduction of PME48 activity revealed by zymogram. Interestingly, the wild-type phenotype was restored in pme48-/- with the optimum germination medium supplemented with 2.5 mm calcium chloride, suggesting that in the wild-type pollen, the weakly methylesterified homogalacturonan is a source of Ca(2+) necessary for pollen germination. Although pollen-specific PMEs are traditionally associated with pollen tube elongation, this study provides strong evidence that PME48 impacts the mechanical properties of the intine wall during maturation of the pollen grain, which, in turn, influences pollen grain germination.
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Christelle
authors.initials: C
authors.lastname: Leroux
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Sophie
authors.initials: S
authors.lastname: Bouton
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Kiefer-Meyer
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Tohnyui Ndinyanka
authors.initials: TN
authors.lastname: Fabrice
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Alain
authors.initials: A
authors.lastname: Mareck
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Guénin
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Françoise
authors.initials: F
authors.lastname: Fournet
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Christoph
authors.initials: C
authors.lastname: Ringli
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Jérôme
authors.initials: J
authors.lastname: Pelloux
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Azeddine
authors.initials: A
authors.lastname: Driouich
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Patrice
authors.initials: P
authors.lastname: Lerouge
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.).
authors.forename: Arnaud
authors.initials: A
authors.lastname: Lehner
authors.affiliation: Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.) jean-claude.mollet@univ-rouen.fr.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mollet
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media / Q000494:pharmacology; D004951:Esterification / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination; D006720:Homozygote; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D010368:Pectins / Q000378:metabolism; D010641:Phenotype; D011058:Pollen / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D053205:Pollen Tube / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D003470:Culture Media; D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C000601797:PME48 protein, Arabidopsis; D002118:Calcium; C003181:polygalacturonic acid