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Photosynthesis in a changing world: photosynthesis and abiotic stresses
Agriculture, Ecosystems and Environment 106 (2005) 115–117 www.elsevier.com/locate/agee
Preface
Photosynthesis in a changing world: photosynthesis and abiotic stresses
The global environment is changing with changes especially driven by increasing temperature and CO2 (IPCC, 2001). These key variables affect plant growth, development and function, starting with photosynthesis, the most important process in the plant world, sustaining life on earth (Drake et al., 1997). Photosynthesis is an ancient process and it has adapted in the past to different life conditions and environmental changes. On the other hand, photosynthesis is very sensitive to the environment, immediately sensing minimal environmental changes and triggering a series of adjustments eventually leading to adaptation through changes of primary production. Nowadays, the world is undergoing a series of ‘‘novel’’ environmental changes predominantly caused by anthropogenic activities (IPCC, 2001). Whether these factors, alone or in combination with independent changes of environment, will positively or negatively affect photosynthesis, and will trigger the onset of adaptive responses on photosynthesis (Long et al., 2004), remains to be determined. The effects of global changes on photosynthesis can be extremely complex, reflecting the natural plant biodiversity but also the microclimate diversity. The world’s terrestrial ecosystems constitute a continuum from virtually pristine to intensively managed and highly modified systems devoted to production. To consider the negative effects of environmental changes (abiotic stress) on photosynthesis means to look only at the dark side of the story. Photosynthesis
is also the only natural process sequestering a massive amount of CO2 from the atmosphere. This sink effect is of extraordinary importance because it can counteract the present trend toward a rise of atmospheric CO2 (Lenton and Huntingford, 2003). Thus, terrestrial ecosystems play an important role in the carbon cycle. The consequence of global change on plant life (whether positive or negative) need to be assessed timely, and the negative effects need to be controlled and smoothened especially in environmentally fragile areas. Agroecosystems are essential to human well-being. They supply the bulk of humanity’s food and fibre, and they cover a large portion of the Earth’s land area. Many of these terrestrial ecosystems are already threatened by damage to soil and water resources. Major land-use changes will greatly increase this stress, driven by increasing demands for agricultural products from a growing population (Reddy and Hodges, 2000). Moreover, the combination of elevated temperatures and the increased incidence of environmental stress (particularly drought and salinity), will probably constitute the greatest risk caused by global climate change to agricultural ecosystems in arid or semiarid areas of the world (Luo and Mooney, 1999; Centritto et al., 2002). Climate change will be a major cause of soil salinisation in vast areas of the globe and, thus, will increase the processes of soil degradation, which lead to desertification. Among these areas is the Mediterranean, where the climatic conditions (water scarcity, increasing soil salinity, extreme summer
0167-8809/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.agee.2004.10.001
116
Preface / Agriculture, Ecosystems and Environment 106 (2005) 115–117
temperatures) and the anthropogenic pressure (bringing to soil and water over-exploitation for agricultural and industrial practices, and polluting the environment) led to an increasing menace of desertification with potentially catastrophic consequences for plant biodiversity, agricultural and forestry activities, and the whole environment. Thus, it is necessary to learn as much details as possible on how and to which extent agricultural ecosystems are and will be affected by current and predicted environmental changes. The ability to capitalise on the beneficial effects of global change, while avoiding or reducing adverse effects, will require a strong predictive capability. Moreover, in perspective, the need of safeguard of the environment will be a priority for the next generations. This issue of AGEE reports original papers and contribution reviewing the field of plant–environment interaction, with emphasis on abiotic stress factors exacerbated by global change. Environmental stresses and pollution cause serious problems to photosynthesis. Because there is still much uncertainty in this field, intensive research should contribute to a deeper understanding of the mechanisms by which plants adapt to and cope with adverse environments and survive. Edreva presents a comprehensive review on reactive oxygen species (ROS), with emphasis on the ROS generation and scavenging at chloroplast level. This knowledge could constitute a basis for ‘‘molecular’’ breeding and genetic engineering of stressresistant crops which might contribute to a sustainable agricultural system. In a companion paper, Edreva also outlines the contribution of non-photosynthetic pigments to the protection of plants from excess light and UV radiation, as well as the mechanisms involved. Of all the environmental stresses in the global environment, drought and salt are probably the most important in determining plant productivity worldwide. Chartzoulakis and Psarras describe the likely effects of future climate change in the area of Crete (Greece) and discuss the factors that will most probably affect photosynthesis and productivity in this typical semi-arid Mediterranean environment. In their review Cifre et al. summarise the current knowledge on grapevine responses to water stress, and show the potential interest of some physiological indicators which could better assess the irrigation schedule and dosage for a sustainable, water use efficient production of high quality grapevines.
Whereas Paranychianakis and Chartzoulakis, analysing the effects of irrigations using saline water on photosynthesis, provide important information to adopt appropriate management practices to minimize the salinisation of agricultural land and the impacts of salinity on crops’ productivity. Among the original papers, the first two present studies on chlorophyll fluorescence, one of the most suitable technique to study in vivo stress physiology, particularly when the stress target is the photochemistry of photosynthesis. Pietrini et al. show fluorescence transients and pigment contents during a photooxidative cold shock and recovery in mandarin; Myœliwa-Kurdziel and Strzalka provide some insight into the mechanism of heavy metal toxicity towards the protochlorophyllide to chlorophyllide photoreduction, the crucial step in chlorophyll biosynthesis in angiosperms. As we have already briefly noted, rising temperature and [CO2] are the associated, most important climate change factors, certainly contributed by industrial revolution. They importantly affect plant growth and physiology, although their effects can be opposite, at least in terms of photosynthesis versus photorespiration competition, and drive secondary stress factors such as drought and nutritional stresses. Velikova et al. investigates if the protective effect of isoprene against heat stress is associated to a reduced production of reactive oxygen species and to a low peroxidation of membrane lipids in reed plants. Lambreva et al. analyse the short-term response of photosynthesis to elevated [CO2] in combination to high temperature and light intensity in bean. Whereas, Centritto shows the effects of the interaction between of water deficit and elevated [CO2] on photosynthetic limitations and carbon partitioning in cherry seedlings. The last six papers analyse the effects of drought on crops. Delfine et al. show the effect of water stress on carbon assimilation and allocation to monoterpenes in two commercially important officinal plants: spearmint and rosemary. Patakas et al. and de Souza et al. report the ecophysiological responses of field grown grapevines subjected to either various levels of water stress, or to different irrigation systems, i.e. partial root zone drying (PRD) and deficit irrigation. The comparative responses to PRD and regulated deficit irrigation in common bean have also been analysed by
Preface / Agriculture, Ecosystems and Environment 106 (2005) 115–117
Wakrim et al. Finally, Wahbi et al. and Centritto et al. show the effects of PRD on the agronomic and photosynthetic responses of adult olive trees grown in field conditions under arid climate. We hope that researchers working in the field of agronomy, plant biology, soil science, and environmental sciences will be interested in reading the several contributions reported in this special issue. Our aim was to exchange competence and expertise in order to improve our understanding of how and to what extent the climate, and its factors, will affect, and in many case will set a limit to, the primary process of plant life and in turn agricultural ecosystems.
References Centritto, M., Lucas, M.E., Jarvis, P.G., 2002. Gas exchange, biomass, whole-plant water-use efficiency and water uptake of peach (Prunus persica) seedlings in response to elevated carbon dioxide concentration and water availability. Tree Physiol. 22, 699–706. Drake, B.G., Gonza`lez-Meler, M.A., Long, S.P., 1997. More efficient plants: a consequence of rising atmospheric CO2? Annu. Rev. Plant Physiol. Mol. Biol. 48, 607–637.
117
IPCC, 2001. Climate Change 2001: IPCC Third Assessment Report. Intergovernamental Panel on Climate Change. Cambridge University Press, Cambridge, On-line at: http://www.grida.no/ climate/ipcc_tar/. Lenton, T.M., Huntingford, C., 2003. Global terrestrial carbon storage and uncertainties in its temperature sensitivity examined with a simple model. Glob. Change Biol. 9, 1333–1352. Long, S.P., Ainsworth, E.A., Rogers, A., Ort, D.R., 2004. Rising atmospheric carbon dioxide: plants FACE the future. Annu. Rev. Plant Biol. 55, 591–628. Luo, Y., Mooney, H.A., 1999. Carbon Dioxide and Environmental Stress. Academic Press, San Diego. Reddy, K.R., Hodges, H.F., 2000. Climate Change and Global Crop Productivity. CABI Publishing, Wallingford.
Mauro Centritto* CNR–IIA, Via Salaria Km 29,300, 00016 Monterotondo Scalo (Roma), Italy Francesco Loreto CNR–IBAF, Via Salaria Km 29,300, 00016 Monterotondo Scalo (Roma), Italy *Corresponding author E-mail address: [email protected] (M. Centritto)
Preface
Photosynthesis in a changing world: photosynthesis and abiotic stresses
The global environment is changing with changes especially driven by increasing temperature and CO2 (IPCC, 2001). These key variables affect plant growth, development and function, starting with photosynthesis, the most important process in the plant world, sustaining life on earth (Drake et al., 1997). Photosynthesis is an ancient process and it has adapted in the past to different life conditions and environmental changes. On the other hand, photosynthesis is very sensitive to the environment, immediately sensing minimal environmental changes and triggering a series of adjustments eventually leading to adaptation through changes of primary production. Nowadays, the world is undergoing a series of ‘‘novel’’ environmental changes predominantly caused by anthropogenic activities (IPCC, 2001). Whether these factors, alone or in combination with independent changes of environment, will positively or negatively affect photosynthesis, and will trigger the onset of adaptive responses on photosynthesis (Long et al., 2004), remains to be determined. The effects of global changes on photosynthesis can be extremely complex, reflecting the natural plant biodiversity but also the microclimate diversity. The world’s terrestrial ecosystems constitute a continuum from virtually pristine to intensively managed and highly modified systems devoted to production. To consider the negative effects of environmental changes (abiotic stress) on photosynthesis means to look only at the dark side of the story. Photosynthesis
is also the only natural process sequestering a massive amount of CO2 from the atmosphere. This sink effect is of extraordinary importance because it can counteract the present trend toward a rise of atmospheric CO2 (Lenton and Huntingford, 2003). Thus, terrestrial ecosystems play an important role in the carbon cycle. The consequence of global change on plant life (whether positive or negative) need to be assessed timely, and the negative effects need to be controlled and smoothened especially in environmentally fragile areas. Agroecosystems are essential to human well-being. They supply the bulk of humanity’s food and fibre, and they cover a large portion of the Earth’s land area. Many of these terrestrial ecosystems are already threatened by damage to soil and water resources. Major land-use changes will greatly increase this stress, driven by increasing demands for agricultural products from a growing population (Reddy and Hodges, 2000). Moreover, the combination of elevated temperatures and the increased incidence of environmental stress (particularly drought and salinity), will probably constitute the greatest risk caused by global climate change to agricultural ecosystems in arid or semiarid areas of the world (Luo and Mooney, 1999; Centritto et al., 2002). Climate change will be a major cause of soil salinisation in vast areas of the globe and, thus, will increase the processes of soil degradation, which lead to desertification. Among these areas is the Mediterranean, where the climatic conditions (water scarcity, increasing soil salinity, extreme summer
0167-8809/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.agee.2004.10.001
116
Preface / Agriculture, Ecosystems and Environment 106 (2005) 115–117
temperatures) and the anthropogenic pressure (bringing to soil and water over-exploitation for agricultural and industrial practices, and polluting the environment) led to an increasing menace of desertification with potentially catastrophic consequences for plant biodiversity, agricultural and forestry activities, and the whole environment. Thus, it is necessary to learn as much details as possible on how and to which extent agricultural ecosystems are and will be affected by current and predicted environmental changes. The ability to capitalise on the beneficial effects of global change, while avoiding or reducing adverse effects, will require a strong predictive capability. Moreover, in perspective, the need of safeguard of the environment will be a priority for the next generations. This issue of AGEE reports original papers and contribution reviewing the field of plant–environment interaction, with emphasis on abiotic stress factors exacerbated by global change. Environmental stresses and pollution cause serious problems to photosynthesis. Because there is still much uncertainty in this field, intensive research should contribute to a deeper understanding of the mechanisms by which plants adapt to and cope with adverse environments and survive. Edreva presents a comprehensive review on reactive oxygen species (ROS), with emphasis on the ROS generation and scavenging at chloroplast level. This knowledge could constitute a basis for ‘‘molecular’’ breeding and genetic engineering of stressresistant crops which might contribute to a sustainable agricultural system. In a companion paper, Edreva also outlines the contribution of non-photosynthetic pigments to the protection of plants from excess light and UV radiation, as well as the mechanisms involved. Of all the environmental stresses in the global environment, drought and salt are probably the most important in determining plant productivity worldwide. Chartzoulakis and Psarras describe the likely effects of future climate change in the area of Crete (Greece) and discuss the factors that will most probably affect photosynthesis and productivity in this typical semi-arid Mediterranean environment. In their review Cifre et al. summarise the current knowledge on grapevine responses to water stress, and show the potential interest of some physiological indicators which could better assess the irrigation schedule and dosage for a sustainable, water use efficient production of high quality grapevines.
Whereas Paranychianakis and Chartzoulakis, analysing the effects of irrigations using saline water on photosynthesis, provide important information to adopt appropriate management practices to minimize the salinisation of agricultural land and the impacts of salinity on crops’ productivity. Among the original papers, the first two present studies on chlorophyll fluorescence, one of the most suitable technique to study in vivo stress physiology, particularly when the stress target is the photochemistry of photosynthesis. Pietrini et al. show fluorescence transients and pigment contents during a photooxidative cold shock and recovery in mandarin; Myœliwa-Kurdziel and Strzalka provide some insight into the mechanism of heavy metal toxicity towards the protochlorophyllide to chlorophyllide photoreduction, the crucial step in chlorophyll biosynthesis in angiosperms. As we have already briefly noted, rising temperature and [CO2] are the associated, most important climate change factors, certainly contributed by industrial revolution. They importantly affect plant growth and physiology, although their effects can be opposite, at least in terms of photosynthesis versus photorespiration competition, and drive secondary stress factors such as drought and nutritional stresses. Velikova et al. investigates if the protective effect of isoprene against heat stress is associated to a reduced production of reactive oxygen species and to a low peroxidation of membrane lipids in reed plants. Lambreva et al. analyse the short-term response of photosynthesis to elevated [CO2] in combination to high temperature and light intensity in bean. Whereas, Centritto shows the effects of the interaction between of water deficit and elevated [CO2] on photosynthetic limitations and carbon partitioning in cherry seedlings. The last six papers analyse the effects of drought on crops. Delfine et al. show the effect of water stress on carbon assimilation and allocation to monoterpenes in two commercially important officinal plants: spearmint and rosemary. Patakas et al. and de Souza et al. report the ecophysiological responses of field grown grapevines subjected to either various levels of water stress, or to different irrigation systems, i.e. partial root zone drying (PRD) and deficit irrigation. The comparative responses to PRD and regulated deficit irrigation in common bean have also been analysed by
Preface / Agriculture, Ecosystems and Environment 106 (2005) 115–117
Wakrim et al. Finally, Wahbi et al. and Centritto et al. show the effects of PRD on the agronomic and photosynthetic responses of adult olive trees grown in field conditions under arid climate. We hope that researchers working in the field of agronomy, plant biology, soil science, and environmental sciences will be interested in reading the several contributions reported in this special issue. Our aim was to exchange competence and expertise in order to improve our understanding of how and to what extent the climate, and its factors, will affect, and in many case will set a limit to, the primary process of plant life and in turn agricultural ecosystems.
References Centritto, M., Lucas, M.E., Jarvis, P.G., 2002. Gas exchange, biomass, whole-plant water-use efficiency and water uptake of peach (Prunus persica) seedlings in response to elevated carbon dioxide concentration and water availability. Tree Physiol. 22, 699–706. Drake, B.G., Gonza`lez-Meler, M.A., Long, S.P., 1997. More efficient plants: a consequence of rising atmospheric CO2? Annu. Rev. Plant Physiol. Mol. Biol. 48, 607–637.
117
IPCC, 2001. Climate Change 2001: IPCC Third Assessment Report. Intergovernamental Panel on Climate Change. Cambridge University Press, Cambridge, On-line at: http://www.grida.no/ climate/ipcc_tar/. Lenton, T.M., Huntingford, C., 2003. Global terrestrial carbon storage and uncertainties in its temperature sensitivity examined with a simple model. Glob. Change Biol. 9, 1333–1352. Long, S.P., Ainsworth, E.A., Rogers, A., Ort, D.R., 2004. Rising atmospheric carbon dioxide: plants FACE the future. Annu. Rev. Plant Biol. 55, 591–628. Luo, Y., Mooney, H.A., 1999. Carbon Dioxide and Environmental Stress. Academic Press, San Diego. Reddy, K.R., Hodges, H.F., 2000. Climate Change and Global Crop Productivity. CABI Publishing, Wallingford.
Mauro Centritto* CNR–IIA, Via Salaria Km 29,300, 00016 Monterotondo Scalo (Roma), Italy Francesco Loreto CNR–IBAF, Via Salaria Km 29,300, 00016 Monterotondo Scalo (Roma), Italy *Corresponding author E-mail address: [email protected] (M. Centritto)