plant microbe interactions beneficial n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Plant/Microbe Interactions - Beneficial PowerPoint Presentation
Download Presentation
Plant/Microbe Interactions - Beneficial

Loading in 2 Seconds...

play fullscreen
1 / 31

Plant/Microbe Interactions - Beneficial - PowerPoint PPT Presentation


  • 468 Views
  • Uploaded on

Plant/Microbe Interactions - Beneficial. Interactions involving plant roots Rhizoplane - the surface of the plant root, root hairs present large surface area (> 6 m 2 for an average wheat plant). Only 4 - 10% of the rhizoplane is in direct contact with soil microbes.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Plant/Microbe Interactions - Beneficial' - lisandra-church


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
plant microbe interactions beneficial
Plant/Microbe Interactions - Beneficial
  • Interactions involving plant roots
    • Rhizoplane - the surface of the plant root, root hairs present large surface area (> 6 m2 for an average wheat plant). Only 4 - 10% of the rhizoplane is in direct contact with soil microbes.
    • Rhizosphere - the area of the soil directly influenced by plant roots (extremely variable). Soil that remains after shaking off roots.
plant microbe interactions beneficial1
Plant/Microbe Interactions - Beneficial
  • Interactions involving plant roots
    • Rhizosheath - some plants excrete a mucous-like material that cement sand grains together around the root. Most common in dry soils.
plant microbe interactions beneficial2
Plant/Microbe Interactions - Beneficial
  • R/S ratio - indicates the importance of the root system to the microbial community.
    • R  the number or biomass of microbes in the rhizoshphere.
    • S  the number or biomass of microbes in root-free soil.
    • R/S typically between 5 and 20, can be >100
plant microbe interactions beneficial3
Plant/Microbe Interactions - Beneficial
  • In the rhizosphere (relative to root-free soil)
    • abundance of Gram-negative rods is higher
    • abundance of Gram-positive rods and cocci is lower
  • Reflects the influence of plant root exudates and the selection of organisms with high growth rates
plant microbe interactions beneficial4
Plant/Microbe Interactions - Beneficial
  • Root exudates
    • amino acids (proteins)
    • keto acids (TCA cycle)
    • vitamins (enzyme co-factors)
    • sugars (C and energy)
plant microbe interactions beneficial5
Plant/Microbe Interactions - Beneficial
  • Roots surrounded by active microbes produce more exudates than roots in sterile soil.
  • The roots are not just leaky, there is an interaction with the microbial community.
  • As a plant grows the community in the rhizosphere changes to fast-growing, growth factor-requiring organisms.
plant microbe interactions beneficial6
Plant/Microbe Interactions - Beneficial
  • Microbial populations are clearly benefited by the interaction with roots . . . but what does the plant get?
  • One major plant benefit is nutrient uptake . . .
plant microbe interactions beneficial7
Plant/Microbe Interactions - Beneficial
  • Mycorrhizae
    • mutualistic associations between fungi and plant roots
    • fungi become integrated into the root structure
    • both partners benefit (not a disease)
slide9

Mycorrhizal symbioses

  • Advantages:
    • Enhancing plant nutrient adsorption
    • Reducing soil born diseases
    • Improving plant water resistant
mycorrhizae
Mycorrhizae

Tree root

Fungal hyphae

Mycorrhizal structure

plant microbe interactions beneficial8
Plant/Microbe Interactions - Beneficial
  • Ectomycorrhizae
    • fungi form an external sheath on the root and extends into intercellular spaces (not inside individual cells)
    • approximately 40 mm thick
    • the root association can be up to 40% fungi by dry weight
plant microbe interactions beneficial9
Plant/Microbe Interactions - Beneficial
  • Ectomycorrhizae
    • found in most trees in temperate forests
    • benefits to the tree include:
        • drought resistance
        • pathogen resistance
        • enhanced nutrient uptake (PO4 and K)
        • increased tolerance to pH changes
        • increased root growth
plant microbe interactions beneficial10
Plant/Microbe Interactions - Beneficial
  • Ectomycorrhizae
    • benefits to the fungus includes:
      • first access to plant exudates
      • direct benefit from trees photosynthetic activity
plant microbe interactions beneficial11
Plant/Microbe Interactions - Beneficial
  • Endomycorrhizae
    • fungal mycelia penetrate both between cells and inside individual cells
    • heath, rododendrons, laurels, orchids
    • the fungal partner does not fix nitrogen, but does seem to enhance the uptake of combined nitrogen
plant microbe interactions beneficial12
Plant/Microbe Interactions - Beneficial
  • Endomycorrhizae
    • orchids are pollinated at night and some mycorrhizal fungi are bioluminescent (insect attraction?)
    • rRNA sequence data place the origin of the endomycorrhizal fungi at or near the origin of land plants . . . may indicate a long term co-evolution.
plant microbe interactions beneficial13
Plant/Microbe Interactions - Beneficial
  • Vesicular-Arbuscular (VA) Endomycorrhizae
    • the most common of all mycorrhizal associations
    • Phytobionts : 80% of plant species
    • wheat, corn, potatoes, beans, soybeans, tomatoes, strawberries, apples, oranges, grapes, cotton, tobacco, tea, coffee, cocoa, sugar cane, sugar maple, rubber . . .
    • Phylum : Glomeromycota
    • Genera: Glomus, Paraglomus, Sclerocystis, Acaulospora, Entrophospora, Gigaspora, Scutellospora, Diversispora, Geosiphon, and Archaeospora
plant microbe interactions beneficial14
Plant/Microbe Interactions - Beneficial
  • Vesicular-Arbuscular (VA) Endomycorrhizae
    • extensive network of mycelia that extends well out into the soil surrounding the root hair (vesicle and tree-like shapes)
    • arbuscules = tree-like
    • vesicles = intracellular fungal storage structures which are lipid containing bodies
plant microbe interactions beneficial15
Plant/Microbe Interactions - Beneficial

Colonization of a root by an endomycorrhizal fungus

(Brundrett et al. 1985 Can. J. Bot. 63: 184).

plant microbe interactions beneficial17
Plant/Microbe Interactions - Beneficial
  • Vesicular-Arbuscular (VA) Endomycorrhizae
    • benefits to the tree include:
      • drought resistance
      • pathogen resistance
      • enhanced nutrient uptake (combined nitrogen, P, Zn, & Cu)
      • increased tolerance to pH changes
      • increased root growth
interaction of am agricultural practices
Interaction of AM & Agricultural Practices
  • Fertilizer Application : High P
  • Crop Rotation : non-host plant species
  • Tillage : reduced / no tillage practices
  • Liming
propagation cycle of amf
Propagation cycle of AMF

a. Spores of (i) Gigaspora, (ii) Glomus, (iii) Entrophospora, and (iv) Acaulospora; b. germinating spore; c. hyphal network and spores; d. hypha and spores around root; e. hyphal penetration inside root; f. intracellular arbuscules; g. intraradical vesicles; h. colonized plant

inoculum propagation
Inoculum Propagation
  • Pot-culture propagation

- Isolation of AMF pure culture strain : single spore

- Choice of a host plant : Allium porrum, Sorgum bicolor, Zea Mays, Paspalum otatum

  • In vitro propagation on root-organ culture
in vitro propagation
In Vitro Propagation

a. Isolated spores; b. germinating colonized root segment; c. carrot root in culture; d. AMF root-organ culture; e. closer view of an AMF root-organ culture

slide30

In Vivo Propagation

a. Seeding mycorrhizal substrates; b. mycorrhizal seedling production; c. growth chamber inoculum propagation; d. root growth and colonization; e. colonized seedlings; f. field inoculum propagation