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Journal of Plant Physiology 161 (2004) 1189–1202



Drought-induced responses of photosynthesis and antioxidant metabolism in higher plants
Attipalli Ramachandra Reddya,*, Kolluru Viswanatha Chaitanyaa, Munusamy Vivekanandanb


School of Life Sciences, Pondicherry University, Pondicherry 605 014, India Department of Biotechnology,School of Life Sciences, Bharatidasan University, Tiruchirapalli 620 024, India

Received 16 October 2003; accepted 7 January 2004

KEYWORDS Abscisic acid; Antioxidants; Antioxidative enzymes; Drought; Higher plants; Photosynthesis

Environmental stresses trigger a wide variety of plant responses, ranging from altered gene expression and cellular metabolism to changes in growth ratesand crop yields. A plethora of plant reactions exist to circumvent the potentially harmful effects caused by a wide range of both abiotic and biotic stresses, including light, drought, salinity, high temperatures, and pathogen infections. Among the environmental stresses, drought stress is one of the most adverse factors of plant growth and productivity. Understanding the biochemical and molecularresponses to drought is essential for a holistic perception of plant resistance mechanisms to water-limited conditions. Drought stress progressively decreases CO2 assimilation rates due to reduced stomatal conductance. Drought stress also induces reduction in the contents and activities of photosynthetic carbon reduction cycle enzymes, including the key enzyme, ribulose1,5-bisphosphatecarboxylase/oxygenase. The critical roles of proline and glycinebetaine, as well as the role of abscisic acid (ABA), under drought stress conditions have been actively researched to understand the tolerance of plants to dehydration. In addition, drought stress-induced generation of active oxygen species is well recognized at the cellular level and is tightly controlled at both the production and consumptionlevels in vivo, through increased antioxidative systems. Knowledge of sensing and signaling pathways, including ABA-mediated changes in response to drought stress, is essential to improve crop management. This review focuses on the ability and strategies of higher plants to respond and adapt to drought stress. & 2004 Elsevier GmbH. All rights reserved.

Abbreviations: A, foliar photosyntheticrate; AA, ascorbic acid; ABA, abscisic acid; APX, ascorbate peroxidase; CAT, catalase; COD, choline oxidase; CMO, choline monoxygenase; CDH, choline dehydrogenase; DHA, dehydroascorbate; FBPase, fructose-1,6bisphosphatase; GlyBet, glycine betaine; GR, glutathione reductase; LEA, late embryogenesis abundant; MDA, monodehydroascorbate; MDAR, monodehydroascorbate reductase; POD, peroxidase; ROS,reactive oxygen species; RWC, relative water content; RuBP, ribulose1,5-bisphosphate; SPS, sucrose phosphate synthase; SOD, superoxide dismutase *Corresponding author. Tel.: þ91-0413-2655991; fax: þ91-0413-2655211. E-mail address: arreddy@yahoo.com (A.R. Reddy). 0176-1617/$ - see front matter & 2004 Elsevier GmbH. All rights reserved. doi:10.1016/j.jplph.2004.01.013

1190 A.R. Reddyet al.

Plants are subjected to several harsh environmental stresses that adversely affect growth, metabolism, and yield. Drought, salinity, low and high temperatures, flood, pollutants, and radiation are the important stress factors limiting the productivity of crops (Lawlor, 2002). Several biotic (insects, bacteria, fungi, and viruses) and abiotic (light, temperature, wateravailability, nutrients, and soil structure) factors affect the growth in higher plants (as reviewed by Lichtenthaler, 1996, 1998). Among these, drought is a major abiotic factor that limits agricultural crop production. Plants experience drought stress either when the water supply to roots becomes difficult or when the transpiration rate becomes very high. These two conditions often coincide under...
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