title: In muro fragmentation of the rhamnogalacturonan I backbone in potato (Solanum tuberosum L.) results in a reduction and altered location of the galactan and arabinan side-chains and abnormal periderm development.
abstract: Rhamnogalacturonan (RG) I is a branched pectic polysaccharide in plant cell walls. Rhamnogalacturonan lyase (eRGL) from Aspergillus aculeatus is able to cleave the RG I backbone at specific sites. Transgenic potato (Solanum tuberosum L.) plants were made by the introduction of the gene encoding eRGL, under the control of the granule-bound starch synthase promoter. The eRGL protein was successfully expressed and translated into an active form, demonstrated by eRGL activity in the tuber extracts. The transgenic plants produced tubers with clear morphological alterations, including radial swelling of the periderm cells and development of intercellular spaces in the cortex. Sugar compositional analysis of the isolated cell walls showed a large reduction in galactosyl and arabinosyl residues in transgenic tubers. Immunocytochemical studies using the LM5 (galactan) and LM6 (arabinan) antibodies also showed a large reduction in galactan and arabinan side-chains of RG I. Most of the remaining LM5 epitopes were located in the expanded middle lamella at cell corners of eRGL tubers, which is in contrast to their normal location in the primary wall of wild type tubers. These data suggest that RG I has an important role in anchoring galactans and arabinans at particular regions in the wall and in normal development of the periderm.
authors.affiliation: Wageningen University, Laboratory of Plant Breeding, Binnenhaven 5, 6709 PD Wageningen, The Netherlands.
authors.forename: Ronald J F J
authors.initials: RJ
authors.lastname: Oomen
authors.forename: Chantal H L
authors.initials: CH
authors.lastname: Doeswijk-Voragen
authors.forename: Maxwell S
authors.initials: MS
authors.lastname: Bush
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Vincken
authors.forename: Bernhard
authors.initials: B
authors.lastname: Borkhardt
authors.forename: Lambertus A M
authors.initials: LA
authors.lastname: van den Broek
authors.forename: Julia
authors.initials: J
authors.lastname: Corsar
authors.forename: Peter
authors.initials: P
authors.lastname: Ulvskov
authors.forename: Alphons G J
authors.initials: AG
authors.lastname: Voragen
authors.forename: Maureen C
authors.initials: MC
authors.lastname: McCann
authors.forename: Richard G F
authors.initials: RG
authors.lastname: Visser
mesh_terms: D001230:Aspergillus / Q000201:enzymology; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D005685:Galactans / Q000378:metabolism*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D010368:Pectins / Q000378:metabolism*; D018547:Plant Stems / Q000201:enzymology* / Q000254:growth & development; D030821:Plants, Genetically Modified; D011133:Polysaccharide-Lyases / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D011198:Solanum tuberosum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D005685:Galactans; D011134:Polysaccharides; C042491:rhamnogalacturonan I; C030080:araban; D010368:Pectins; D011133:Polysaccharide-Lyases