How microbes interact with roots of plant is described in this ppt

1. ROOT MICROBE INTERACTIONS

2. • Root microbe associations are quite complex
and may involve invasion of the host root by
the organism.
• Microorganisms may remain free living in the
soil. Sometimes the association may prove
beneficial to the plant or it may be pathogenic
and cause injury.
• These microorganisms play a significant role in
the inorganic nutrition of plants.

3. • The rhizosphere is the narrow region of soil or substrate that is
directly influenced by root secretions and associated soil
microorganisms known as the root microbiome.
• Soil pores in the rhizosphere can contain many bacteria and other
microorganisms that feed on sloughed-off plant cells, termed
rhizodeposition, and the proteins and sugars released by roots,
termed root exudates.
• This symbiosis leads to more complex interactions, influencing
plant growth and competition for resources.
• Soil bacteria can assist in making phosphorus available to the
plant.

4. Mycorrhizae
• Mycorrhizae literally translates to “fungus-root.”
• Mycorrhiza defines a mutually beneficial relationship between the root of a
plant and a fungus that colonizes the plant root.
• In many plants, mycorrhiza are fungi that grow inside the plant’s roots, or on
the surfaces of the roots.
• The plant and the fungus have a mutually beneficial relationship, where the
fungus facilitates water and nutrient uptake in the plant, and the plant
provides food and nutrients created by photosynthesis to the fungus.
• Not all plants will have mycorrhizal associations.

5. Types of Mycorrhizae:
• The two main types of mycorrhizae are ectomycorrhizae and
endomycorrhizae. They are categorised according to where the fungi
colonise on the plants.
• ECTOMICORRHIZAE:
• Ectomycorrhiza, also known as EcM, usually develops connections
between woody plants (like beech, birch, willow, oak, pine, fir and
spruce) and fungi belonging to the Ascomycota, Basidiomycota, and
Zygomycota.
• Ectomycorrhizae (‘’outer fungus root’’) are common and wrap fungal
threads around the root tip in a hyphal sheath or mantle.
• Hyphae also penetrate the root cortex (outer layer) between but
outside root cells, in what is called a Hartig net.

7. ENDOMYCORRHIZAE:
• Endomycorrhizal relationships are characterized by a penetration
of the cortical cells by the fungi and the formation of arbuscules
and vesicles by the fungi.
• In other words, endomycorrhiza have an exchange mechanism on
the inside of the root, with the fungi’s hyphae extending outside
of the root.
• ENDOMYCORRHIZAE are further subdivided into specific types:
Arbuscular Mycorrhizae, Ericaceous Mycorrhizae, Arbutoid
Mycorrhizae, and Orchidaceous Mycorrhizae.

9. • Vasicular-Arbuscular Mycorrhizae (VAM)
• This type of Mycorrhizae is most commonly found in the majority of the
world’s vegetation.
• Vasicular-Arbuscular mycorrhiza (VAM) is formed by the symbiotic
association between certain phycomycetous fungi and angiosperm roots.
• The fungus colonizes the root cortex forming a mycelial network and
characteristic vesicles (bladder-like structures) and arbuscules
(branched finger-like hyphae).
• The arbuscules are the most characteristic structures, formed
intracellularly and probably having an absorptive function.
• The vesicles are terminal swellings of hyphae formed inter and
intracellularly having a storage function.

11. Nutrients move from the Mycorrhizal fungi to
the root cells:
• In ectomycorrhizae , inorganic phosphate may simply diffuse from
the hyphae in the hartig net and be absorbed by the root cortical
cells.
• In vasicular arbuscular Mycorrhizae,the situation may be more
complex to nutrients may diffuse from intact arbuscules to root
cortical cells.
• Deficiency of nutrients may tend to promote infection,where as
plants under a good supply of nutrients tend to suppress infection.