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VOCABULARYForget not, exam includes ENGLISH WORDS1. Involve2. Bundle3. Sheath4. Subsequent5. Ambient6. Stick together7. Determine8. Evolution9. Thrive10. Allow
COMPTETENCIESStudents, after mastering the materials ofPlant Physiology course, should be able to:1. To explain the assimilation of CO2 to be carbohydrate
(sugars) in C4 and CAM plants2. To explain the diffusion of CO2 from the atmosphere
into the site of assimilation in the chloroplasts of C4 andCAM plants
3. To explain reactions, enzymes and products involved inthe reduction of CO2 to be carbohydrate in C4 andCAM plants
4. To explain the effect of several environmental factorson photosynthesis
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C3 Plants: AvenaSativa (380x)
C4 Plants:(a). Zea maize (350x)(c). Gomphrena
(740x)
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Ribulose 1,5bisphosphate
3-phosphoglycerate(PGA)
Triosephosphate
Sucrose
From the lightreaction of
photosynthesisATP
AtmosphericCO2
NADPHNADP+
ADP + Pi
C3 PCA
Fixation
C3 plants
C4 plants
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CO2 Fixation in C3 vs. C4 Plants
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BasicReaction ofCO2reductionin C4plants
ASSIMILATION REGENERATION
TRANSPORTTRANSPORT
DECARBOXYLATION
HCO3
PEP(Phosphoenol
pyruvate)
Mesophyllcell
C4 acid(e.g., malate, aspartate)
C3 acid
C3 acid
C4 acidBundlesheath
cell
Fixation byC3 PCR cycle
Plasma membrane
Cell wall
Atmospheric
Plasmodesmata
CO2
CO2
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1. NADP-malic enzyme type
2. NAD-malic enzyme type
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3. Phosphoenolpyruvate carboxykinase type
The reduction cost of 1 mol CO2 via PCR =2mol NADPH+3 mol ATP
Total reduction cost of 1 mol CO2 = ?
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CO2 Fixation in a CAM Plant
CO2 Reduction in CAM (CrassulaceanAcid Metabolism) Plants
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The molecule of PEP caboxylase contain a componentoriginated from amino acid Serine (serine residue)
Diurnal regulation of CAM phosphoenolpyruvate (PEP)carboxylase which is achieved by phosphorylation of a serineresidue. Ser = Serine
Physiological andEcological Aspects of
PHOTOSYNTHESIS
1. Light2. Water3. Temperature4. CO25. NutrientsEtc.
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CER = CO2 in – CO2 out
CO2 outCO2 in
CO2 in = CO2 out
No Carbohydrate accumulationNO GROWTH
CER = CO2 Exchange Rate
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EFFECT OF LIGHT ONPHOTOSYNTHESIS
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LIGHT = PAR = PPFD(Photosynthetic photon flux density)
Sifat optis dari daun kacang panjang
Light transmitted and reflected increases with wavelength
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Photosynthetic EfficiencyThe slope of the linear phase of the response curve is ameasure of "photosynthetic efficiency" -- how efficientlysolar energy is converted into chemical energy.
Quantum yieldQuantum yield
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Light Compensationpoint= 2.074/1.143= 14.5
Light Compensationpoint= 3.704/0.069= 53.7
Effect of previous plant experience
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Keadaan terbuka Keadaan ternaungi
Distribusi khloroplast dalamselAtas : penampang
membujurBawah :
Penampangmelintang
dark
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Soybean in Malang maxEmax P/PPFDQEXP1PP
Pmax QE 1/QE
CER1 34.0 0.044 22.6
CER2 23.9 0.067 14.9
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maxEmax P/PPFDQEXP1PP
maxmax
/1 PPPFDQEXPP
PE
maxmax
/1 PPPFDQEXPP
PE
PPFDP
QP
P E
maxmax
1ln
y xb a
+ 0
LIGHT: Sun and Shade Plants
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EFFECT OF TEMPERATUREON PHOTOSYNTHESIS
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TEMPERATURE & LIGHT
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Muhlenbergia montana plants grown at 26/16 °C day/night temperature.Arrows indicate the estimated light saturation points used in subsequenttemperature response measurements.
Effect of temperature
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from M. montana grown at 26/16 °C or 26/4 °C day/nighttemperatures. Rubisco activity was determined on leaves of plantsgrown at 26/16 °C (mean±SE, N=4–6)
EFFECT OF WATER ONPHOTOSYNTHESIS
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Water
Maximum O2evolution at variousΨw in sunflower leafdiscs. Tang et al.,2002
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EFFECT OF CO2 ONPHOTOSYNTHESIS
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Ambient [CO2]
CO2 compensation point for C4 plants - CO2 comp point is 0-5 ppm for C 3 plants - CO2 comp point is 30-70
ppm C 4 plants have developed mechanisms
for surviving and thriving in hotter, drierclimates.
C 3 plants survive and thrive in moremoderate climates.
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FIG. 1. Change in CO2 compensation point and dark respiration withage of snapbean leaves. All assays were run on leaflets of thesecond trifoliate (Smith et al., 1976).
CO2 compensation
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Net C02 assimilationrate versus leaf internalC02 concentrationresponse curves for the0.50 (open squares) and0.05 mM Pi (closedcircles) treatments. Thearrows indicate the pointon the curves whichcorrespond to the meanphotosynthetic rate of 34Pa C02.
Intercellular [CO2]
Greenhouse grown plants were allowed to adapt to the growthchamber for at least 48 h before measurement. Three separateexperiments representing a total of eight leaves from each treatmentwere measured. Leaves were illuminated with saturating PPFD (>1100Imol.m2. -s1). Each datum represents a single determination. ). Laueret al., 1989
EFFECT OF NUTRIENTS ONPHOTOSYNTHESIS
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Heliotropic response of soybeans grown on 0.50 mM Pi (left) or 0.05 mM Pi(right). The photographs were taken at 1 p.m. (b, e). Lauer et al., 1989
High Phosphate (0.5 mM Pi) Low Phosphate (0.05 mM Pi)
NUTRIENTS:Nitrogen
Rate of CO2assimilation at highirradiance versus leafnitrogen content, bothexpressed per unit leafarea for several plantspecies. Evans, 1989
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Light response curve (A versus PPFD) for the 0.50 (open squares) and 0.05mm Pi (closed circles) treatments. Greenhouse grown plants were allowed toadapt to the growth chamber for 6 d before measurement. Leaves wereoriented perpendicular to the light source during measurement. Four leavesof each treatment were measured. Each datum represents a singledetermination. ). Lauer et al., 1989
NUTRIENTS:Phosphate
• C4 saturates at a lower CO2 concentration• C4 has higher carboxylation efficiency• Maximum CO2 assimilation at high CO2 concentration is higher in C3.
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in A. edulis wild-type plants
O2
Fm maximum fluorescence level after asaturating light pulse on a dark-adapted leaf
F′m maximum fluorescence after a saturatinglight pulse from a leaf during steady-statephotosynthesisFobasal fluorescence level ona dark-adapted leaf
F′o minimum fluorescence from a leaf followingsteady-state illumination and quickly darkadapted under a pulse of far-red light to fullyoxidize PSI
Fs steady-state fluorescence on an illuminatedleaf
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Which of these curves corresponds with the highestphotosynthetic efficiency?
