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(P) Salt Stress (& Toxic Spores) - Coggle Diagram
(P) Salt Stress (& Toxic Spores)
What are the effects of salt stress on plants? How do they adapt to this stressor? What about toxic spore elements?
Effects 🧂
Osmotic stress
rapid
growth inhibition of young leaves (cf. water stress) :white_small_square:
Ion stress (toxicity)
slower
accelerated senescence mature leaves :older_man:
high Na+ / K+ ratio and high total ion concentrations inhibit
enzymes
and general
protein synthesis
:building_construction:
high Na+ concentrations affect PM
permeability
by replacing Ca2+ ions :door:
Na+ disruption of ion homeostasis generally affects
nutrient
status :shallow_pan_of_food:
. competition with uptake and binding of K+
. inhibition of photosynthesis ...
Secondary effects
(via membranes, metabolism, ROS ...)
Adaptations 🧂
limiting
osmotic
stress (cfr. water stress)
limiting
exposure
to salt
especially in
root and shoot meristems
actively growing and photosynthesizing leaves
how?
moderate accumulation for
osmotic
adjustment :inbox_tray:
+spontaneously
by electro-chemical potential gradients established by the H+-ATPase
non-selective passive uptake via non-
selective cation channels (
NSCC
)
more specific transporters
exclusion and compartmentalization (vacuole) of toxic concentrations :outbox_tray:
export to the apoplast or into the vacuole by
Na+/H+- antiporters
Ca2+-mediated ‘SOS signaling’
activated by Na+ binding to GIPC (sphingolipid) in PM => how ccs sense salt stress
salt/osmotic stress sensed
ABA
Ca2+ influx by NSCC
1 more item...
e.g.
AtSOS1
into apoplast
AtNHX
into vacuole
blocking the apoplastic route of water and ion transport :forbidden:
secretion by specialized salt glands (and crystallization) 🧊
Toxic Elements (As, Al, Cd, Cu, Ni, Zn, Se...)
Adaptation strategies
exclusion (avoidance)
internal tolerance
compartmentalization
binding to vacuolar organic acids
antioxidants against oxidative stress
sometimes even hyper-accumulation
why?
protection against pathogens and insect herbivores
linked to less efficient use?
some essential co-factors (need some levels of these elements in low concs), some used by other enzymes (SOD)
how?
uptake:
overproduction transporters
e.g.
Nramp type with His-rich region
long-distance transport from roots to leaves using
chelators
e.g.
free amino acid histidine
or the chelator nicotianamine
used in
phyto-remediation :seedling: