Climate Change and Plants Climate Change and Plants

Climate Change and Plants

Climate Change and Plants What is climate change? What happens to plants when climate changes? (CO 2 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, 200

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 CO 2 -eq. (c) Share of different sectors in total anthropogenic GHG emissions in 2004 in terms of CO 2 -eq. (Forestry includes deforestation. ) (IPCC, 2007)

Plant-Environment Interaction (www. biologie. uni-hamburg. de/b-online/virtuallaboratory/Section-12. html) Deforestation in Brazil

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 CO 2 + 6 H 2 O + Light → C 6 H 12 O 6 + 6 O 2 (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 CO 2 and O 2 *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 - C 3 plants (70% of all the plants) Two different mechanisms developed by land plants 2 - C 4 plants (C 4 photosynthetic carbon fixation) 3 - CAM plants (Crassulacean acid metabolism (CAM))

Some examples of C 3 plants Wheat plants All the trees are C 3 plants Arabidopsis plants Potato plants

Some examples of C 4 plants Sugarcane plants Maize plants Amaranth plants

Some examples of CAM plants Pineapple plants Orchid plants Cactus plants

C 3 photosynthesis Ancestral times (long before today) CAM and C 4 phosynthesis evolved 10 -35 million years ago (CO 2 levels below 200 ppm) C 3 plants (most of the plants) C 4 plants CAM plants Today (around 395 ppm CO 2 levels )

C 4 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 C 4 Amaranthus hypochondriacus (amaranth). (Berry et al. , 2013

Minimum energy losses calculated for 1000 k. J of incident solar radiation Calculations assume a leaf temperature of 30 o. C and an atmospheric [CO 2] of 380 ppm. The theoretical maximal photosynthetic energy conversion efficiency is 4. 6% for C 3 and 6% C 4 plants, calculated based on the total initial solar energy and the final energy stored in biomass. (Zhu et al. , 2008)

Atmospheric [CO 2] 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 [CO 2] on C 3 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 460 ppm Future 700 ppm Representative plants of Abutilon theophrasti (C 3) grown at glacial through future [CO 2]. (Dippery et al. , 1995) Five-month-old Gmelina arborea plants grown in open top chambers under ambient and elevated [CO 2]. (Reddy et al. , 2010)

The effects of temperature and [CO 2] on energy conversion efficiencies of C 3 and C 4 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. : Ru. BP carboxylase) Regulation of cellular p. H 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 CO 2 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. : Ru. BP carboxylase) Photosynthesis (ATP synthesis, CO 2 fixation, maintenance of stroma p. H, 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