Plant growth promotic microorganisms Flashcards
microbiome
Community of microorganisms in a
specific environment (with specific conditions) where they each have a function and interact with each other.
phyllosphere
above ground area
rhizosphere
below ground area
epiphytes
- harmless microorganisms found on the surface of the plant
- nutrient uptake
endophytes
- harmless microorganisms found in the inside of the plant
- plant growth and defence
edaphic conditions
Soil conditions; pH, nutrient levels, moisture, composition
mycorrhizal fungi
Provide phosphorus, nitrogen and water
Rhizobia in root nodules
Fix nitrogen from the air in compounds that plants can use as protein building blocks
actinomycetes
Inhibit the growth of several plant pathogens
drought stress
1) hydrogel formation:
Some microbes produce hydrogels that retain soil moisture, ensuring plants have
access to water even in dry conditions
2) root growth:
Microbes in the rhizosphere boost root
development, helping plants absorb more water from the soil during drought
3) exopolysaccharide production:
Certain microbes produce exopolysaccharides, forming a protective
matrix in soil. This matrix improves water retention, helping plants access moisture during drought
salinity stress
1) ion homeostasis:
Metabolites bind excessive salt ions in the soil, preventing them from entering plant roots and causing toxicity
2) osmotic adjustment:
Microbial metabolites like organic osmolytes help plants maintain water balance under salty conditions, preventing dehydration
3) induction of stress-responsive genes:
Metabolites trigger the activation of genes that produce proteins and compounds aiding plants in tolerating salt stress
chemical signalling
Plants release molecules like flavonoids into the root zone, attracting helpful bacteria
biochemical crosstalk
Once in proximity, plants and bacteria exchange molecular signals, triggering specific responses in each other
plant growth promoting bacteria
a group of beneficial soil bacteria that colonise the root surface and promote the plant growth and health via multiple
mechanisms
plant growth promotion
1) Biochemical mechanisms: mobilisation and provision of plant nutrients
2) Rhizobacterial interference with plant
phytohormones
3) Release of molecules (VOCs or signaling
molecules) that can impact plant growth
nitrogen fixation
Some microorganisms (bacteria or even plants) have the ability to fix gaseous dinitrogen directly from the air into
ammonia usable by plants using the enzyme nitrogenase complex
phosphorous solubilisation
achieved by the production of:
- Organic acids: such as acetate; succinate, citrate,…
- Phosphatases
which liberates rthophosphates (simplest form of phosphate) that can be then absorb by plants
siderophore production
- The reduction strategy: protons and organic acids are released to decrease the soil pH and thus increasing iron availability
- The chelation strategy: plant roots release
low-molecular-weight iron-chelating molecules called siderophore that can efficiently bind to iron island then be taken up by root cells
phytohormones
chemicals compounds released by plants that promote and influence plant growth
The production of phytohormones leads to root proliferation, thus a higher total root surface, leading to more nutrient absorption
quorum sensing
a key mechanism that regulate gene expression in response to the population density, facilitated by the buildup of signaling molecules
is involved in several important processes such as virulence, symbiosis and survival
volatile organic compound
some microbes can release VOC’s with
growth-promoting capabilities
biological compounds
Microorganisms can synthesize a wide range of compounds resulting in many effects on the plant health
derived from the secondary metabolism
microbiota
are the living organisms living in the microbiome
biostimulant
any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits,
- hormone-containing product
- humic substance
- amino acids containing product
