title: Apple polygalacturonase inhibiting protein1 expressed in transgenic tobacco inhibits polygalacturonases from fungal pathogens of apple and the anthracnose pathogen of lupins.
abstract: Extracts from apple fruit (cultivar "Granny Smith") inhibited the cell-wall degrading polygalacturonase (PG) activity of Colletotrichum lupini, the causal agent of anthracnose on lupins, as well as Aspergillus niger PG. Southern blot analysis indicated that this cultivar of apple has a small gene family of polygalacturonase inhibiting proteins (pgips), and therefore heterologous expression in transgenic tobacco was used to identify the specific gene product responsible for the inhibitory activity. A previously isolated pgip gene, termed Mdpgip1, was introduced into tobacco (Nicotiana tabacum) by Agrobacterium-mediated transformation. The mature MdPGIP1 protein was purified to apparent homogeneity from tobacco leaves by high salt extraction, clarification by DEAE-Sepharose and cation exchange HPLC. Purified MdPGIP1 inhibited PGs from C. lupini and PGs from two economically important pathogens of apple trees, Botryosphaeria obtusa and Diaporthe ambigua. It did not inhibit the A. niger PG, which was in contrast to the apple fruit extract used in this study. We conclude that there are at least two active PGIPs expressed in apple, which differ in their charge properties and ability to inhibit A. niger PG.
authors.affiliation: Agricultural Research Council (ARC)-Vegetable and Ornamental Plant Institute, Biotechnology Division, Private Bag X293, Pretoria 0001, South Africa. doelofse@arc.agric.za
authors.forename: Dean
authors.initials: D
authors.lastname: Oelofse
authors.forename: Ian A
authors.initials: IA
authors.lastname: Dubery
authors.forename: Riaan
authors.initials: R
authors.lastname: Meyer
authors.forename: Melanie S
authors.initials: MS
authors.lastname: Arendse
authors.forename: Inge
authors.initials: I
authors.lastname: Gazendam
authors.forename: Dave K
authors.initials: DK
authors.lastname: Berger
mesh_terms: D000935:Antifungal Agents / Q000302:isolation & purification / Q000378:metabolism; D001203:Ascomycota / Q000201:enzymology / Q000472:pathogenicity; D001234:Aspergillus niger / Q000201:enzymology / Q000472:pathogenicity; D020231:Colletotrichum / Q000201:enzymology / Q000472:pathogenicity; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D005658:Fungi / Q000201:enzymology*; D027845:Malus / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism*; D011096:Polygalacturonase / Q000037:antagonists & inhibitors*; D014026:Nicotiana / Q000235:genetics; D014170:Transformation, Genetic
chemical_list: D000935:Antifungal Agents; D004791:Enzyme Inhibitors; C081479:PGIP protein, plant; D010940:Plant Proteins; D011096:Polygalacturonase