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Climate Change and Plants

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Climate Change and Plants

• What is climate change?
• What happens to plants when climate changes?
• (CO2 concentrations)

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Climate change refers to any change in climate
over time (persists for an extended period,
typically decades or longer), whether due to
natural variability or as a result of human
activity. (IPCC, Synthesis Report 2007)
The Intergovernmental Panel on Climate Change
(IPCC) is the leading international body for the
assessment of climate change. It was established
by the United Nations Environment Programme
(UNEP) and the World Meteorological Organization
(WMO) in 1988 to provide the world with a clear
scientific view on the current state of knowledge
in climate change and its potential environmental
and socio-economic impacts.
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Schematic framework of antropogenic climate
change drivers, impacts and responses (IPCC, 2007)
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Global anthropogenic GHG emissions
(a) Global annual emissions of anthropogenic GHGs
from 1970 to 2004.5 (b) Share of different
anthropogenic GHGs in total emissions in 2004 in
terms of CO2-eq. (c) Share of different sectors
in total anthropogenic GHG emissions in 2004 in
terms of CO2-eq. (Forestry includes
deforestation.) (IPCC, 2007)
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Plant-Environment Interaction (www.biologie.uni-h
amburg.de/b-online/virtuallaboratory/Section-12.ht
ml)
Deforestation in Brazil
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Population is rising!

• More research on
• food security
• sustainable agriculture
• biofortification

According to the Food and Agriculture
Organization (FAO), food security "exists when
all people, at all times, have physical and
economic access to sufficient, safe and
nutritious food to meet their dietary needs and
food preferences for an active and healthy life"
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Photosynthesis 6 CO2 6 H2O Light
?  C6H12O6 6 O2
(Campell, 2008)
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Two main steps of photosynthesis Light
reactiions Calvin-Benson Cycle
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(Berry et al., 2013)
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Photosynthetic leaf cells of Arabidopsis thaliana
visualized using LSCM (Berry et al., 2013)
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(No Transcript)
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The carboxylation and the oxygenation of ribulose
1,5-biphosphate catalyzed by rubisco. (Taiz and
Zeiger, 2010)
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• Balance between Calvin-Benson and
  Photorespiration
• Inherent to plant (the kinetic properties of
  rubisco)
• Temperature
• Concentrations of CO2 and O2

Under stress conditions ( high illumination,
high temperature , water deficiency) Photorespirat
ion Minimizes the photoinhibition of the
photosynthetic apparatus
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• There are three types of plants according to
  their photosynthesis mechanisms
• 1- C3 plants (70 of all the plants)
• Two different mechanisms developed by land plants
• 2- C4 plants (C4 photosynthetic carbon fixation)
• 3- CAM plants (Crassulacean acid metabolism
  (CAM))

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Some examples of C3 plants
Wheat plants
All the trees are C3 plants
Potato plants
Arabidopsis plants
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Some examples of C4 plants
Sugarcane plants
Maize plants
Amaranth plants
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Some examples of CAM plants
Pineapple plants
Orchid plants
Cactus plants
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C3 photosynthesis CAM and C4 phosynthesis
evolved C3 plants (most of the plants) C4
plants CAM plants
Ancestral times (long long before
today) 10-35 million years ago (CO2 levels
below 200 ppm) Today (around 395 ppm
CO2 levels )
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C4 Carbon Cycle Phosphoenolpyruvate carboxylase
(PEPCase) Kranz anatomy
CAM Plants Open their stomata during night
Phosphoenolpyruvate carboxylase (PEPCase) Malic
acid
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Kranz anatomy in a leaf section from C4
Amaranthus hypochondriacus (amaranth). (Berry et
al., 2013)
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Minimum energy losses calculated for 1000 kJ of
incident solar radiation Calculations assume a
leaf temperature of 30 oC and an atmospheric
CO2 of 380 ppm. The theoretical maximal
photosynthetic energy conversion efficiency is
4.6 for C3 and 6 C4 plants, calculated based on
the total initial solar energy and the final
energy stored in biomass. (Zhu et al., 2008)
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Atmospheric CO2 Increases!
1800

280 µmol mol-1 Today

395 µmol mol-1 Estimation for the
end of this century (IPCC, 2007)
530-970 µmol mol-1

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Schematic of the direct initial effects of rising
CO2 on C3 plant production. (Long et al., 2005)
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Other Environmental Parameters Temperature Radia
tion Water availability Salinity Nutrition
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Glacial 150 ppm
Pre-industry 270 ppm
Current 350 ppm
360 ppm
460 ppm
Future 700 ppm
Five-month-old Gmelina arborea plants grown in
open top chambers under ambient and elevated
CO2. (Reddy et al., 2010)
Representative plants of Abutilon theophrasti
(C3) grown at glacial through future
CO2.(Dippery et al., 1995)
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The effects of temperature and CO2 on energy
conversion efficiencies of C3 and C4
photosynthesis for the past, current, and
future atmospheric conditions. (Zhu et al., 2008)
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A diagrammatic representation of the hypotheses
that seek to describe the mechanism underlying
loss of photosynthetic capacity when sucrose
accumulates in the mesophyll. (Long et. al., 2005)
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(Reddy et al., 2010)
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Site of synthesis (source)
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Site of growth, storage, reproduction
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Carbon mobilization in land plants (Taiz and
Zeiger, 2010)
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(Knoblauch and Peters, 2013)
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Mg Constituent of chlorophyll molecule (6 -
25 of total magnesium is bound to
chlorophyll) Required by many enzymes (e.g. RuBP
carboxylase) Regulation of cellular pH and the
cation-anion balance Protein Synthesis
Photosynthesis Carbohydrate partitioning
Mg-deficiency Increase in the shoot-root dry
weight ratio Massive accumulation of
carbohydrates and related impairment in
photosynthetic CO2 fixation Over-reduction in the
photosynthetic electron transport
chain Generation of ROS (Cakmak and Kirkby, 2008)
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Schematic presentantion of changes in
Mg-deficient leaves (Cakmak and Kirkby, 2008)
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Effect of Mg deficiency on starch content in
sugar beet leaves, as detected by lugol
staining.(Hermans et al., 2005)
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K Establishing cell turgor and maintaning cell
electroneutrality Required as a cofactor for more
than 40 enzymes Protein synthesis (e.g. RuBP
carboxylase) Photosynthesis (ATP synthesis, CO2
fixation, maintenance of stroma pH, stomatal
regulation) Phloem transport (loading of sucrose,
massflow-driven solute transport in the sieve
tubes)
An increase in potassium content in the leaves
increases Rate of photosynthesis Rate of
photorespiration
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More reserach is needed to further understand
Plant-Environment Interaction The affects of
climate change to plants (Individual and combined
factors -nutrient deficiencies, temperature
changes, water deficiency- should be
investigated) The reponses of plants to climate
change