Physiology and Molecular Biology of Stress ... - KHAM PHA MOI

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CHAPTER 6
PHOTOOXIDATIVE STRESS
ATTIPALLI R. REDDY AND AGEPATI S. RAGHAVENDRA
Department of Plant Sciences, School of Life Sciences,
University of Hyderabad, Hyderabad 500 046, India
(e-mail: arreddy@yahoo.com)
Key words: Antioxidants, Light stress, Oxygen scavenging system,
Plant acclimation, Photoinhibition, Reactive oxygen species,
Scavenging enzymes, Signal transduction
1. INTRODUCTION
Plants are exposed to several environmental stresses, that adversely affect metabolism,
growth and yield. Yet, plants are also known to adapt to these stress conditions by
modulating their metabolism and physiology. These stress factors include abiotic
(drought, salinity, light, CO 2
, soil nutrients and temperature) and biotic (bacteria, fungi,
viruses and insects) components. Among abiotic factors, non-optimal light intensity
and temperature can be considered as the most serious limiting factors which limit the
growth and yield of plants (Foyer, 2002; Reddy et al., 2004). Also, environmental fluctuations
often result in ‘stress’ which ultimately limit the overall plant performance. The
consequences of environmental stresses on the whole plant are quite complex, dealing
with structural and metabolic functions. Understanding plant responses to the external
environments is of greater significance for making crops stress tolerant. One of the
most deleterious effect of environmental stress on plants is “oxidative stress” in cells,
which is characterized by the accumulation of potential harmful reactive oxygen species
(ROS) in tissues. Photooxidative stress in plants is mostly induced by the absorption
of excess excitation energy leading to over-reduction of the electron transport
chains generating ROS.
Although excess light absorption is known to cause photooxidative stress,
paradoxically photo-chilling, salinity and drought are also responsible in inducing photooxidative
stress in plants (Asada, 1999; Foyer and Noctor, 2000; Reddy et al., 2004).
This review concentrates on recent developments on the effects of light stress- induced
oxidative responses in plants. We focus on various physiological, biochemical,
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K.V. Madhava Rao, A.S. Raghavendra and K. Janardhan Reddy (eds.),
Physiology and Molecular Biology of Stress Tolerance in Plants, 157–186.
© 2006 Springer. Printed in the Netherlands.