title: Interaction between Vitis vinifera and grape phylloxera: changes in root tissue during nodosity formation.
abstract: OBJECTIVE
  The interaction between the gall-forming grapevine parasite, phylloxera, and the susceptible grapevine species Vitis vinifera was investigated.
  
  
  METHODS
  Phylloxera and grapevines were cocultivated using both potted and micropropagated grapevines. Development of nodosities on primary roots was studied by microscopy and histochemistry, and nodosities were analysed for biochemical changes and changes in gene expression.
  
  
  RESULTS
  Within a nodosity, phylloxera fed at a site in the root cortex. Nodosity development was characterized by swelling of the root tissue distal to the feeding site, lack of development of a suberized endodermis, and starch and amino acid accumulation, and was eventually followed by root necrosis. No evidence of a defence response was observed in pre-necrotic nodosities, but defence-type responses were observed in tissue adjacent to necrotic regions. Changes in gene expression were not detected by northern hybridization using DNA probes encoding a range of V. vinifera transcripts.
  
  
  CONCLUSIONS
  Nodosities on V. vinifera potentially function as nutrient reservoirs, and defence responses to phylloxera attack were not detected.
authors.affiliation: The University of Adelaide, Department of Horticulture, Viticulture and Oenology, PMB 1 Glen Osmond 5064, Australia. alisonk@tepapa.govt.nz
authors.forename: Alison V
authors.initials: AV
authors.lastname: Kellow
authors.forename: Margaret
authors.initials: M
authors.lastname: Sedgley
authors.forename: Robyn
authors.initials: R
authors.lastname: Van Heeswijck
mesh_terms: D000818:Animals; D006430:Hemiptera / Q000145:classification / Q000235:genetics*; D006790:Host-Parasite Interactions; D018517:Plant Roots / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D010941:Plant Tumors / Q000235:genetics / Q000469:parasitology*; D027843:Vitis / Q000235:genetics / Q000469:parasitology*