tougher plants: beating stress by protecting photosynthesis in genetically modified plants based on...
TRANSCRIPT
Tougher Plants:Beating Stress by Protecting Photosynthesis in Genetically Modified Plants
Based on a case study by R. Pals-Rylaarsdam and M.L. Tischler Department of Biological ScienceBenedictine University, Lisle, IL
Plants are subject to many stresses
• The main stressors are:Cold Heat Salt
Frost damageHeat damage
Road runoff Irrigation evaporation or drought
Glycine betaine is a molecule that moderates stresses in plants
CH2C
OH
O
NH3C
CH3H3C
Plants are subject to many stresses
• The main stressors are:Cold Heat Salt
Frost damageHeat damage
Road runoff Irrigation evaporation or drought
Wild type TransgenicPlants were exposed to 3C for 7 days, then transferred to the warm greenhouse.
NB: This figure is a simulation of a figure in the original article.
What does wild type mean?
A. Unaltered experimental group
B. Group showing uncontrolled or “wild” grow
C. Genetically altered group
D. Group displaying the greatest variance in an observed trait
Unaltere
d experimental ..
.
Group sh
owing uncontro
...
Genetically
altere
d group
Group disp
laying t
he gre...
0% 0%0%0%
What does glycine betaine do for the leaves, flowers and fruits in cold-exposed plants?
What does glycine betaine do?
WT: wild type tomato plants
L1-L9: different lines of transgenic plants
Figure 3. Effects of chilling on various growth parameters. Five-week-old greenhouse-grown wild type and independent homozygous transgenic lines (L1, L5) were chilled (3°C) for 5 days, then returned to greenhouse.
Which photosynthesis process is most effected by ion leakage?
A. Whether cells can capture light
B. Whether the Calvin cycle will function
C. Whether ATP synthase will function
D. Whether electrons will transfer from PS II
Wheth
er cells
can ca
pture
...
Wheth
er the Calvi
n cycle
...
Wheth
er ATP sy
nthase
wi..
Wheth
er electr
ons will
t...
0% 0%0%0%
Plants are subject to many stresses
• The main stressors are:Cold Heat Salt
Frost damageHeat damage
Road runoff Irrigation evaporation or drought
Figure 4. Changes in the oxygen-producing activity of PSII determined with thylakoid membranes isolated from leaves after exposed to different temperatures 25, 30, 35, 40, 45, or 50°C in the chambers for 4 h, in wild type and transgenic plants. The values are mean + SE of three independent experiments.
WT: Wild type tobacco plants and genetically modified tobacco plants
20 25 30 35 40 45 50 550
100
200
300
400
WT
Genetically modified
Temperature of treatment (oC)
Oxyg
en
-evo
lvin
g a
ctiv
ity o
f P
SII
(m
mo
l O
2 m
g-1
Ch
l h
-1)
Which process in photosynthesis produces O2?
A. PS I
B. PS II
C. ATP synthase
D. Light capture
PS I PS II
ATP synth
ase
Light c
apture
0% 0%0%0%
Make two observations from the data
Figure 4. Changes in the oxygen-producing activity of PSII determined with thylakoid membranes isolated from leaves after exposed to different temperatures 25, 30, 35, 40, 45, or 50°C in the chambers for 4 h, in wild type and transgenic plants. The values are mean + SE of three independent experiments.
Photosystem II
Structure of Photosystem II, PDB 2AXT http://en.wikipedia.org/wiki/File:PhotosystemII.PNG
Which part of the molecule goes through the membrane?
A. Blue box
B. Red oval
Blue box
Red oval
0%0%
Structure of Photosystem II, PDB 2AXT http://en.wikipedia.org/wiki/File:PhotosystemII.PNG
So, the blue box is trans-membrane.
The part below the blue box is associated with the membrane.
Which of the following could explain why increased temperatures decrease PSII activity?
a. Thylakoid membranes become more permeable to ions
b. The chlorophyll breaks down
c. The peripheral proteins lose their ability to bind to the transmembrane proteins
d. Water cannot bind to PSII to form oxygen
Thylakoid m
embranes b
...
The chloro
phyll bre
aks ...
The peripheral p
roteins l
...
Wate
r cannot b
ind to PSI...
0% 0%0%0%
Plants are subject to many stresses
• The main stressors are:Cold Heat Salt
Frost damageHeat damage
Road runoff Irrigation evaporation or drought
Protein sizes are measured in kilodaltons (kDa)a: subunit of 18 kDab: subunit of 23 kDac: subunit of 33 kDa
Make two observations
Which subunit is most stable and likely to be in the membrane?
A. AB. BC. C
A B C
0% 0%0%
Which subunit is least stable and likely to be a peripheral subunit?
A. AB. BC. C
A B C
0% 0%0%
What does glycine betaine do to protect PSII activity?A. Betaine protects peripheral proteins
again dissociation due to salt
B. Betaine protects transmembrane proteins from dissociation due to salt
C. Betaine promotes dissociation of transmembrane and peripheral proteins in the thylakoids
D. Betaine appers to have no impact on membrane proteins of the thylakoids
Betaine pro
tects perip
her..
Betaine pro
tects tr
ans...
Betaine pro
motes d
issoc..
.
Betaine appers
to have
..
0% 0%0%0%
All the parts need to be together for photosynthesis!
PS II needs to work
Membrane can’t leak so ATP synthase works