24/4 - microbe interaktions Flashcards

1
Q

Why study plant beneficial microbes?

A

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

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2
Q

Naturally occurring microbes in soil - vilka finns

A

Bacteria, archaea, protozoa, yeasts, filamentous fungi

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3
Q

hur spelar jorden in när det kommer till microbial profiles

A

Different soils different microbial profiles

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4
Q

hur mycket bakterier finns i jorden

A

1 gram of soil contain >109 bacteria of >107 taxa.

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5
Q

hur utvecklas det till en microbe interaktions

A

Parasitism – commensalism - mutualism.

Beneficial microbes has co-evolved with (specific) plant hosts.

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6
Q

Microbiota - microbiome

A

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

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7
Q

Ecosystem service - vad?

A

promote growth & stress tolerance of plants

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8
Q

Hur kan microberna i en växt variera

A

Beror på var på växten de finns

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9
Q

What is the nature of the natural plant microbiome?

A

Arabidosis root/leaf microbiome - relative abundance of bacterial phyla!

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10
Q

How to characterize soil microbiomes?

A
  • Cultivation in vitro – total – specific media
  • Metagenomics
  • Targeted sequencing
  • Fingerprinting
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11
Q

How to characterize soil microbiomes?

A
  • Cultivation in vitro – total – specific media
  • Metagenomics
  • Targeted sequencing
  • Fingerprinting
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12
Q

Biofertilizer def

A

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

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13
Q

Phytostimulator def

A

Microorganism, with the ability to produce
phytohormones such as indole acetic acid,
gibberellic acid, cytokinins and ethylene

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14
Q

Biopesticide (Biocontrol agent) def

A

Microorganisms that promote plant growth

by controlling phytopathogenic agents

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15
Q

Biostimulant

A

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.

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16
Q

Most studied PGPR/PGPF/biocontrol agents (BCA) are strains of e.g

A

Trichoderma, Pseudomonas, Bacillus

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17
Q

Vad är bra med PGPR

A

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).

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18
Q

Vad är bra med PGPR

A

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).

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19
Q

Priming of plant defense to abiotic and biotic stress

A

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?

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20
Q

Why not maximal growth and defense for plants?

A

är en våg mellan defence och growth/reproduction
- var energin ska få

Complex
hormonal
interplay

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21
Q

PRRs

A

pattern recognition receptors) located on the cell surface are specific to
different compound classes

PRR binding initiate-elicit plant defense.

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22
Q

Pathogens cause PTI, ETS, ETI.

A

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.

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23
Q

MAMP

A

beneficial microbes

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24
Q

How do beneficial microbes (MAMP) become accepted by a plant?

A

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

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25
Q

Biofilm produktion

A
The underground environment is
complex and competetive.
Good rhizosphere competence is
needed for PGPR/BCA.
The biofilm embed the bacteria on
the rhizoplane and avoid exposure
to other microbes.
The role of root border cells
produced by plants are unclear in
this process.
Root border cells are suggested
to be used to trap certain
pathogens by exudation of DNA
and other compounds.
26
Q

Biological control of pathogens depend on different factors

effecter

A
Direct effect
antagonism
hyperparasitism/predation
antibiosis
lytic enzymes
interference (signalling,...)

Indirect effect
competition
host plant growth promotion
improved host resistance

27
Q

ISR

A

Induced Systemic Resistance

Priming of plant defense (Induced Systemic Resistance -ISR).

28
Q

hur ser signaleringen ut?

A

Signalling differs for various forms of induced resistance

29
Q

Priming of plant defense to insect pests

A

beneficial insekts
herbivores - growth promation induced resistance
benificial microbes - nutrient allocation, plant defence, root exudates

30
Q

Volatile signaling in plant defense and growth

A

Attacked plants can activate neighbours
Volatile compounds- Volatile Organic Compounds (VOC)
Methyljasmonate (MJ) – insect attack
Methylsalicylate (MS) – pathogen attack
PGPR can release VOCs that stimulate plant growth and defense

31
Q

VOC

A

Volatile Organic Compounds

32
Q

vad can genomics hjälpa till med

A

helpful for studies of biocontrol strains and action!?

Prediction of useful PGPR/BCA strains?
Secondary metabolites – yes!

33
Q

Prediction of PGPR/BCA and relative efficacy!

A

Mechanisms by which microbes promote growth promotion and health of plants!

Bacterial rhizosphere competence –
flagellum and chemotaxis.
Plant growth–promoting traits e.g.:
ACC deaminase (lowering ethylene),
auxin (IAA) biosynthesis,
biological nitrogen fixation,
volatile organic compounds (VOC),
phosphorus solubilization,
siderophore production, ….
Competition traits
ISR possibility
Resource allocation: abiotic stress
tolerance
34
Q

Breeding or priming for abiotic/biotic stress management?

A

Common pathways/factors for multiple stressors can be used as ”targets”.

35
Q

Rapid test if microbes increase root system growth - exempel

A

For example Bacillus 5113 stimulates lateral root and root hair formation.
Increased phytohormone activity.

Indirect effect (ISR) to pathogens by root treatment with Bacillus 5113

36
Q

Are plant associated microbes endophytic or epiphytic?

A

Common methods for detecting endophytes within a plant.

37
Q

Desirable properties (as for natural enemies):

A
 Good searching ability for host
 ”Host” specificity
 Reproduction rate
 Adaptability
 Host synchrony - well adapted to different stages of life cycle of target host
 Sustainability
 Ecosafe
38
Q

Biocontrol agents – challenges in field conditions!?

A

Phyllosphere challenges for biocontrol microbes

39
Q

Rhizosphere microbiota is affected by agriculture & environment
exempel?

A
plant species
soil types
agricultural practise
climat
plant diversety
biotic interaktion
40
Q

Is a PGPR always beneficial?

A

no - kan orsaka damage

41
Q

applications - se pp

A

jupp - för myclet målande bilder

42
Q

application natural field vs agricultural

A
Natural
High diversity of plants 
Differential display of roots 
Diversified composition of exudates 
Deposition of heterogeneous organic matter 
Higher microbial diversity 
Effective selection of plants 
Plants rely on microbial partners for nutritional supply 
and protection 

agricultural
Low diversity of plants (or even monoculture)
Homogeneous display of roots
Homogeneous release of exudates
Deposition of homogeneous organic matter
Lower microbial diversity
Defective selection of plants
Higher demand of human interference for plant
nutrition and protection

43
Q

How important are shifts in natural plant microbiomes? Dynamics?

A

diverse: health
dysbiosis: disease

Spelar stor roll för hälsan - pp

44
Q

Crop protection strategies

A
Chemical control
Resistance breeding
Semiochemicals
Natural enemies
PGPR/BCA – priming
Unknown plant defence factors?
Cultivation systems
45
Q

SUMMARY

A

Many beneficial microbes exist in nature.
Microbiomes are complex and depend on several factors.
PGPR and BCA have great potential if low fitness cost for plants.
PGPR and BCA must have good rhizosphere competence.
PGPR and BCA must establish efficiently on roots (leaves).
PGPR and BCA must not trigger plant defense PRR-MAMP…
Priming-IST improve abiotic stress tolerance.
Priming-ISR unique signalling that sensitize innate immunity defense to pathogens.
Useful strategy as part of IPM.
Tools for designing/predicting productive beneficial interaction
Unexplored ecosystem service with great potential

Knowledge gaps
What are the requirements for succesful colonization, priming, ISR?
How predict efficacy ? (field conditions!!)
Can pests develop resistance to primed immunity?
Ecological effects of BCA?
Effects on other crops in crop rotation? Effects on neighbouring habitats?
Can weeds benefit from colonization and become more problematic?

46
Q

Goal: Design future durable crop plant production

A
  1. Discuss some knowledge gaps that exist (and should be dealt with) in order to get more efficient pest control strategies!
  2. What risks with large scale use of PGPR/BCA may need more attention?
  3. Should resurce allocation strategies be more engineered in
    crop plants?
47
Q

allmänt

A

olika rötter - olika microber

Många av de plantorna vi är intresserade av är relativt nya

Plants kan ej flytta på sig och måste därmed lägga mer krut på defence

Ju further from root the lesser bacteria due to small in nr - outcompeated om för långt bort ifrån roten
48
Q

Are okant microbes sopecies specific

A

Yes they are
Plant specific and plant specific - flytta till ett annat område och se hur adoptiv plantan och dess microber är
OUT - operational taxonomic unit - cluster of microbes with similar dna sequense

49
Q

How is the microbion formed

A

Beror på soil type - vilka mo finns tillgängligt - beror lite på vilka plantor som växte där innan
Gradianter in the soil - fytokemikalier, orkaniska stuff
Plant genotype - hur ser cellväggarna ut
Hur vet mo långt bort I från plantan att plantan är där? Kan va random eller rootexudates - extremt viktigt för den här processen - shape the microbiome
Get rid of patogens, mycket secondära mecobolites - deliviring sugers eller liknande in the soil
Upp to 4% av fotosyntetic carbon is exodated - det över - är mycket = är viktigt
Många av de beneficial har flagella så kan röra sig mot plantan - följer gradienten
Qurorum sensing - känner hur många de är - om de är för få kanske de inte agerar men om de är tillräckligt många they act
10¨^7 cfu/ml brukar vara det som behövs
Under 10^5 så förlorar man effekten

50
Q

Varför kan vissa mo var svåra att få att etablera sig

hur löser man det

A

Cultivate on plates

  - vissa gillar ej agr
  - growth conditions - svårt at få till rätt miljö tex syrenicå
  - visa mo behöver andra microber för att fortsätta växa
   - gör andra saker på agarplattan än vad de skulle gra I jorden
   - endast 10% kan tas fram på det här sättet

Meta genomics är vanligare

   - seqvensera den    - utifrpn detta bestämma microdome
51
Q

Problem med Biopesticel

A

Biopesticel - dyrt och time consuming så lättare att registrera det som en phytostimulator - säger att de kan stimulera tillväxt men inte tt det är bra för växten

52
Q

Vad är priming

A

Betyder lite olika saker i olika situationer

Priming gör så att växten snabbare reagerar på threats och kan snabbare komma tillbaka till “sitt vanliga”

53
Q

Why not maximal growth and defence for plants

A

Varför producerar ej plant mer growth hormones så växer mer
Do not really know
Kan växa mer men väljer att ej göra det
Blir en risk istället?

54
Q

How do MAMP become accepted by plans

A

Other kind of signaling - vänlig signal -
Specific sensorer - fetaures on surface hos bra bakterier
Andra signl substanser

Posetiv receptor
Produce some kind of hinhibitor that block reseprot
Stör den inre signaling I växten - stops signaling steps eller transkription factoring
But we do not really know
55
Q

Hur kan man få växten att växa snabbare med hjälp av allt detta?

A

Cytokinin - fytokemikal som stimulerar växten att växa
Bakterier på roots som producerar vitiole som känns igen av löven
Många olika mekanismer som kan användas för att påverka växten

56
Q

SAR?

A

det som produceras gör att insekten inte kan digest the plants

57
Q

Votile signaling

A

Plants signalerar varandra - defens I den nya plant är redan aktiv när insekten kommer dit
Men sabbar ej the plants normal signaling

fint i pp

58
Q

Endophytic or epip

A

Tools som avgör detta
- Pcr in real life
- Reisoloate - kan vara lite tricky
- Label microbes - microscope/ scan the plants
- Fish/pcr - veta den exakta dna sequensen
Alla dessa har sina posetiva sitor och sina negativa

59
Q

vad spelar det för roll om det är en gammal eller ung planta

A

olika microber beroende på ung gammal planta

60
Q

Bökig föreläsning och har ej mycket antekningar att gå på

A

..