title: Inoculation with arbuscular mycorrhizal fungi suppresses initiation of haustoria in the root hemiparasite Pedicularis tricolor.
abstract: OBJECTIVE
  Plant parasitism and arbuscular mycorrhizal (AM) associations have many parallels and share a number of regulatory pathways. Despite a rapid increase in investigations addressing the roles of AM fungi in regulating interactions between parasitic plants and their hosts, few studies have tested the effect of AM fungi on the initiation and differentiation of haustoria, the parasite-specific structures exclusively responsible for host attachment and nutrient transfer. In this study, we tested the influence of AM fungi on haustorium formation in a root hemiparasitic plant.
  
  
  METHODS
  Using a facultative root hemiparasitic species (Pedicularis tricolor) with the potential to form AM associations, the effects of inoculation were tested with two AM fungal species, Glomus mosseae and Glomus intraradices, on haustorium initiation in P. tricolor grown alone or with Hordeum vulgare 'Fleet' (barley) as the host plant. This study consisted of two greenhouse pot experiments.
  
  
  RESULTS
  Both AM fungal species dramatically suppressed intraspecific haustorium initiation in P. tricolor at a very low colonization level. The suppression over-rode inductive effects of the parasite's host plant on haustoria production and caused significant growth depression of P. tricolor.
  
  
  CONCLUSIONS
  AM fungi had strong and direct suppressive effects on haustorium formation in the root hemiparasite. The significant role of AM fungi in haustorium initiation of parasitic plants was demonstrated for the first time. This study provides new clues for the regulation of haustorium formation and a route to development of new biocontrol strategies in management of parasitic weeds.
authors.affiliation: Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, PR China.
authors.forename: Ai-Rong
authors.initials: AR
authors.lastname: Li
authors.forename: Sally E
authors.initials: SE
authors.lastname: Smith
authors.forename: F Andrew
authors.initials: FA
authors.lastname: Smith
authors.forename: Kai-Yun
authors.initials: KY
authors.lastname: Guan
mesh_terms: D049108:Cell Enlargement; D055137:Glomeromycota / Q000378:metabolism*; D001467:Hordeum / Q000469:parasitology*; D006790:Host-Parasite Interactions; D038821:Mycorrhizae / Q000378:metabolism*; D032262:Pedicularis / Q000254:growth & development* / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology*; D013559:Symbiosis