Gene Expression in Early Stages of Micorrhizal Interactions

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Gene Expression in Early Stages of Micorrhizal
Interactions

• By
• Sahel Arora

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What is Mycorrhizae - review

• a mutualistic symbiosis between plant and fungus
• 2 major types
• Endomycorrhizae-- fungal component are Glomales
• Endomycorrhizae --hyphae penetrates the outer
  cells of plant root

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Review -- Ectomycorrhizae

• associated plant species include majority of
  vascular plants
• Essential for health and survival of conifers and
  hardwood species
• the function depends on the ability of the fungal
  symbionts to take up nutrients

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Ectomycorrhizal Organ

• Formation has 4 stages
• Time of the process varies
• Laccaria bicolor Pinus resinosa interaction
  takes eight weeks
• Pisolithus tinctorius Eucalyptus globus takes
  about two weeks

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Fungal gene expression in early symbiotic
interactions between Laccaria bicolor and red pine

• Authors G.K. Podila, J. Zheng, S.
  Balasubramaniam, S. Sundaram, S. Hiremath, J.H.
  Brand, and M.K. Hymes
• Aim to obtain a broad overview on various genes
  involved in the pre-infection stages of
  ectomycorrhizal formation, in the fungal partner
• Uses L. bicolor for the fungal component and
  Pinus resinosa for the plant
• it is known that signaling genes are involved in
  the early stage, the types of genes are unknown

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Materials and Methods

• L. Bicolor was obtained, grown and maintained on
  MMN medium
• In vitro system was used to isolate and analyze
  genes
• cDNA library was constructed

• cDNA complimentary DNA synthesized by using
  reverse transcriptase and ohage vector
• cDNAs represent mRNAs during a) its interaction
  with red pines for 6 72 hrs b) free-living
  conditions

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Materials and Methods

• suppression subtractive hybridization was used to
  generate cDNAs, enriched in IS sequences
• These sequences were used as probes to screen the
  actions of cDNA

• The resulting clones were converted to plasmid
  clones and purified
• The clones went through the membrane array
  analyses and northern analyses for validation

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RESULTS AND DISCUSSION

• The analyses indicated a relative increase in the
  expression of each gene in the interaction over
  the free-living state
• Also, showed an increase in levels of clones
  tested, however there was a variation
• The data identified several regulatory genes and
  insights into gene activities involved