24/4 - microbe interaktions Flashcards
Why study plant beneficial microbes?
Support food security and food safety!
Yield loss of crops due to; abiotic and biotic stress,
nutritional deficiency,….
Supportive agrochemicals often synthetic…
Toxic products in attacked plants (plant or pest origin).
Organic (”durable”) production need novel tools.
By understanding how plants can interact with beneficial
microbes more sustainable crop plant production could be achieved and contribute to circular bioeconomy
Naturally occurring microbes in soil - vilka finns
Bacteria, archaea, protozoa, yeasts, filamentous fungi
hur spelar jorden in när det kommer till microbial profiles
Different soils different microbial profiles
hur mycket bakterier finns i jorden
1 gram of soil contain >109 bacteria of >107 taxa.
hur utvecklas det till en microbe interaktions
Parasitism – commensalism - mutualism.
Beneficial microbes has co-evolved with (specific) plant hosts.
Microbiota - microbiome
Microbiota: taxonomic description of a community
Microbiome: funktional description of a community - can använda fysiolocal tools men idag använd mest dna sequensing
Dessa används ofta som samma sak men det är inte sant
Ecosystem service - vad?
promote growth & stress tolerance of plants
Hur kan microberna i en växt variera
Beror på var på växten de finns
What is the nature of the natural plant microbiome?
Arabidosis root/leaf microbiome - relative abundance of bacterial phyla!
How to characterize soil microbiomes?
- Cultivation in vitro – total – specific media
- Metagenomics
- Targeted sequencing
- Fingerprinting
How to characterize soil microbiomes?
- Cultivation in vitro – total – specific media
- Metagenomics
- Targeted sequencing
- Fingerprinting
Biofertilizer def
A substance that contains live microorganisms
which, when applied on the seed, plant surface
or soil, colonizes the rhizosphere and promote
plant growth through increased supply of primary
nutrients for the host plant
Phytostimulator def
Microorganism, with the ability to produce
phytohormones such as indole acetic acid,
gibberellic acid, cytokinins and ethylene
Biopesticide (Biocontrol agent) def
Microorganisms that promote plant growth
by controlling phytopathogenic agents
Biostimulant
US Farm Bill 180417 USDA “a substance or micro-organism that
when applied to seeds, plants, or the rhizosphere, stimulates natur
processes to enhance or benefit nutrient uptake, nutrient efficiency,
tolerance to abiotic stress, or crop quality and yield.
Most studied PGPR/PGPF/biocontrol agents (BCA) are strains of e.g
Trichoderma, Pseudomonas, Bacillus
Vad är bra med PGPR
PGPR increase plant vigour that improve stress management.
PGPR can also act as Biocontrol agents (BCA) to improve pest resistance
through priming of Induced Systemic Resistance (ISR).
PGPR may also improve abiotic stress tolerance by priming of Induced
Systemic Tolerance (IST).
Vad är bra med PGPR
PGPR increase plant vigour that improve stress management.
PGPR can also act as Biocontrol agents (BCA) to improve pest resistance
through priming of Induced Systemic Resistance (ISR).
PGPR may also improve abiotic stress tolerance by priming of Induced
Systemic Tolerance (IST).
Priming of plant defense to abiotic and biotic stress
Certain chemicals or microbes can prime plant defense.
Sensitization – more rapid and stronger defense upon challenge.
Primed defense is activated only after stress challenge.
Priming agents have low fitness costs in the absence of stress.
For PGPR effect - colonisation/biofilm formation on roots is important.
ISR/IST protection seems long lasting.
Transgenerational?
Why not maximal growth and defense for plants?
är en våg mellan defence och growth/reproduction
- var energin ska få
Complex
hormonal
interplay
PRRs
pattern recognition receptors) located on the cell surface are specific to
different compound classes
PRR binding initiate-elicit plant defense.
Pathogens cause PTI, ETS, ETI.
Conserved microbial elicitors called pathogen-associated molecular patterns (PAMPs) are
recognized by pattern recognition receptors (PRRs). Perception may involve recognition by
intracellular receptors of pathogen virulence molecules called effectors, which causes effectortriggered
immunity (ETI) or effector triggered susceptibility (ETS). Co-evolutionary dynamics
between plants and pathogens differ. PTI and ETI give similar responses.
MAMP
beneficial microbes
How do beneficial microbes (MAMP) become accepted by a plant?
Roots & exudates determine
interactions with other plants
& soil microbiota.
Plant root colonization – critical step to enable successful priming
Plant root colonization by bacteria often followed by biofilm formation