Transcript Slayt 1

Climate Change and Plants
Climate Change and Plants
What is climate change?
What happens to plants when climate changes?
(CO2 concentrations)
“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.
Schematic framework of antropogenic climate change drivers, impacts and responses (IPCC, 2007)
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)
Plant-Environment Interaction
Deforestation in Brazil
(www.biologie.uni-hamburg.de/b-online/virtuallaboratory/Section-12.html)
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"
Photosynthesis
6 CO2 + 6 H2O + Light → C6H12O6 + 6 O2
(Campell, 2008)
Two main steps of photosynthesis
* Light reactiıons
* Calvin-Benson Cycle
(Berry et al., 2013)
Photosynthetic leaf cells of Arabidopsis thaliana visualized using LSCM (Berry et al., 2013)
The carboxylation and the oxygenation of ribulose 1,5-biphosphate catalyzed by rubisco.
(Taiz and Zeiger, 2010)
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)
Photorespiration
Minimizes the photoinhibition of the photosynthetic apparatus
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))
Some examples of C3 plants
Wheat plants
All the trees are C3 plants
Arabidopsis plants
Potato plants
Some examples of C4 plants
Sugarcane plants
Maize plants
Amaranth plants
Some examples of CAM plants
Pineapple plants
Orchid plants
Cactus plants
C3 photosynthesis
Ancestral times (long long before today)
CAM and C4 phosynthesis evolved 10-35 million years ago
(CO2 levels below 200
ppm)
C3 plants (most of
C4 plants
CAM plants
the plants)
Today (around 395 ppm CO2 levels )
C4 Carbon Cycle
Phosphoenolpyruvate carboxylase (PEPCase)
Kranz anatomy
CAM Plants
Open their stomata during night
Phosphoenolpyruvate carboxylase (PEPCase)
Malic acid
Kranz anatomy in a leaf section from C4 Amaranthus hypochondriacus (amaranth). (Berry et al., 2013)
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)
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
Schematic of the direct initial effects of rising [CO2] on C3 plant production. (Long et al., 2005)
Other Environmental Parameters
Temperature
Radiation
Water availability
Salinity
Nutrition
Glacial
150 ppm
Pre-industry
270 ppm
Current
350 ppm
360 ppm
Future
700 ppm
Representative plants of Abutilon theophrasti
(C3) grown at
glacial through future [CO2].(Dippery et
al., 1995)
Five-month-old Gmelina arborea plants
grown in open top
chambers under ambient and elevated
[CO2]. (Reddy et al., 2010)
460 ppm
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)
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)
(Reddy et al., 2010)
Site of synthesis (source)
↓
Site of growth, storage, reproduction
Carbon mobilization in land plants (Taiz and Zeiger, 2010)
(Knoblauch and Peters, 2013)
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)
Schematic presentantion of changes in Mg-deficient leaves (Cakmak and Kirkby, 2008)
Effect of Mg deficiency on starch
content in sugar beet leaves, as
detected by lugol staining.(Hermans et
al., 2005)
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
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