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

(www.biologie.uni-hamburg.de/b-online/virtuallaboratory/Section-12.html)

Deforestation in Brazil

More research on:

* food security* sustainable

agriculture* biofortification

Population is rising!

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"

(Campell, 2008)

Photosynthesis 6 CO2 + 6 H2O + Light →  C6H12O6 + 6 O2

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)PhotorespirationMinimizes 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

All the trees are C3 plants

Wheat plants

Potato plantsArabidopsis plants

Some examples of C4 plants

Maize plants

Sugarcane plants

Amaranth plants

Some examples of CAM plants

Orchid plants

Cactus plants

Pineapple plants

C3 photosynthesis

CAM and C4 phosynthesis evolved

C3 plants (most of the plants)

C4 plantsCAM plants

Ancestral times (long long before today)

10-35 million years ago (CO2 levels below 200 ppm)

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 radiationCalculations 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

Representative plants of Abutilon theophrasti (C3) grown atglacial through future [CO2].(Dippery et al., 1995)

Glacial150 ppm

Pre-industry270 ppm

Current350 ppm

Future700 ppm

Five-month-old Gmelina arborea plants grown in open topchambers under ambient and elevated [CO2]. (Reddy et al., 2010)

360 ppm 460 ppm

The effects of temperature and [CO2] on energy conversion efficienciesof C3 and C4 photosynthesis for the past, current, and futureatmospheric conditions. (Zhu et al., 2008)

A diagrammatic representation of the hypotheses that seek to describe the mechanismunderlying 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 balanceProtein Synthesis Photosynthesis Carbohydrate partitioning

Mg-deficiency

Increase in the shoot-root dry weight ratioMassive accumulation of carbohydrates and related impairment in photosynthetic CO2 fixationOver-reduction in the photosynthetic electron transport chainGeneration 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 electroneutralityRequired as a cofactor for more than 40 enzymesProtein 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 photosynthesisRate 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