Stresul hidric la plante
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Transcript of Stresul hidric la plante
STRESUL HIDRIC LA PLANTE
Prezentare realizata in cadrul proiectului POS CCE - A2-O 2.1.2-2009-2 ID.524, cod SMIS-CSMR 11986
CERCETARI PRIVIND SEMNIFICATIA RELATIEI DINTRE RASPUNSUL GENOMIC, METABOLISMUL FENOLPROPANILOR SI
FOTOSINTEZA IN CONDITII DE STRES ABIOTIC PENTRU OPTIMIZAREA POTENTIALULUI
BIOSINTETIC LA SOIURI DE ZMEUR SI MUR
Raspunsul plantelor la factorul de stress de stress
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Activarea unor procese fiziologice
Alterarea metabolismului
celular
Ozone
Temperaturi extreme
inundatii
seceta
saruri
Recunoasterea stresului
Transducerea semnalului
(Lawlor, 2002)
Ce reprezinta stresul hidric
Potentialul hidric al tesuturilor:
Mic: Ψcell ~-0.5 MPaModerate: Ψcell ~-0.5 to -1.5 MPaSever: Ψcell ~<-1.5 MPa
Continutul relativ de apa:
Mic: ~90%Moderat: 80-60%Sever: <50%
Creosote Bush: Larrea tridentata
Supraviatuire Ψcell of -11.5 MPa
Activitate fotosintetica – 5.0 to -8.0 MPa
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DWSW
DWFW= R
Seceta include urmatoarele conditii:Deficit hidric al soplului , este cauzat de lipsa precipitatiilor si lipsa apei disponibile in sol.Deficit hidric al aerului , RH<20% in atmosfera, transpiratia>>absorbtia apei
Pressure Chamber TechniqueThermocouple Psychrometer Method
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Adaptare vs. Aclimatizare
Stress abiotic
aclimatizarea
Rezistenta- evitare- toleranta
Saguaro
Mojave desert star
Mojave desert star Impatiens capensis
Modificari ale frunzelor
Dissected leaves in Palo Verde
SLA (specific leaf area)
Suprafata foliara/ substanta uscata
Desertice (xeric): 0.02 - 0.12Paduri uscate: 0.36 - 0.70Mezofite: 1.4 -1.6
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Scaderea suprafetei foliare
GR - growth rate
ΨP – turgor
Y - yield threshold (the pressure below which the cell wall resists nonreversible deformation)
m - wall extensibility (the responsiveness of the wall to pressure)
Sistemul radicular –crestrea ratei racina/lastari
Raporta sistem radicular/parte aeriana:
Paduri temparate: ~0.25savana ~0.3 – 0.4desert~0.6-0.9
Micoriza creste volumul radicular
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Deficitul hidric intensifica cresterea radacinilor
Tipul salbatic si mutante ABA-deficient de porumb cultivate in conditii normale si deficitare de apa
of
gro
wth
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Deficitul hidric provoaca abscizia frunzelor
Leaves of young cotton plants abscise in response to water stress
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… inchiderea stomatelor mediata de ABA
ROS – reactive oxygen species
PLC – phospholipase C
cADPR – cyclic ADP-ribose
IP3 – inositol triphosphate
PLC – phospho-lipase D
NO – Nitric oxide
PA – Phosphopatidic acid
R – Receptor
S1P – Spingosine-1- Phosphate
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Deficitul hidric scade rata fotosintezeiEfectul deficitului hidric asupra cresterii
frunzelor si a ratei fotsintezei la floarea soarelui
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Water stress affects translocation of nutrientsRelative effects of water stress on photosynthesis and translocation in sorghum
Plants exposed to 14CO2 for a short time interval. Radioactivity fixed in the leaf taken as a measure of photosynthesis, and loss of radioactivity after removal of 14CO2 taken as a measure of rate of assimilate translocation.
A =gs ( Ca-Ci)A =gm (Ci-Cc)
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How does drought cause the generation of ROS?
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How does drought cause the generation of ROS?
3P680*
3O2 1O2*
O2 •O2– H2O2
SOD
SOD – Superoxide Dismutase
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Fates of sunlight absorbed in the light-harvesting chlorophyll complexes
Chl – chlorophyll 1Chl* – excited singlet chlorophyll3Chl* – excited triplet chlorophyll
P – photochemistry (green)D – safe dissipation of excess excitation energy as heat (red)F – fluorescence3T – triplet pathway, leading to the formation of singlet oxygen (1O2*) and photo-oxidative damage
Demmig-Adams & Adams III 2000 Nature 403: 371
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Actiunea ROS asupra celulelor
3. Scavenging ROS
Enzymes:1) SOD( superoxide dismutase)2) POD (AscorbatPeroxidase)3) CAT (Catalase)
Oxidants:1) carotene2) Vit E3) Vit C 4) GSH5) phenolics