NR
Nitrite reductase
O 3
Ozone
PAL
Phenylalanine ammonia-lyase
Pb
Lead
PCD
Programmed cell death
POD
Peroxidase
PSII
Photosystem II
PTMs
Posttranslational protein modifications
ROS
Reactive oxygen species
SNP
Sodium nitroprusside
SOD
Superoxide dismutase
ZN
Zinc
1
Introduction
Abiotic stress is defined as the harmful impact that nonliving factors including
environment factors exert on the living systems such as plants and animals growing
in the specific vicinity. Both plants and animals have evolved distinct mechanisms
to survive abiotic stress imposed due to extreme climate. Plant survival is often
challenged by a variety of different abiotic stress factors including drought, temperature extremes, heavy metals and salinity in soil, wounding, ozone, and UV-B stress.
Water deficit and high temperatures are perhaps the two major abiotic stresses which
are detrimental to crop growth and yield worldwide [1, 2]. Salts and heavy metal
accumulation in soil is also prevailing in crop lands. Furthermore, recent years have
seen the raising surface O 3 levels due to urbanization and industrial revolution which
has also become toxic both for human health and vegetation [3]. On the other hand,
the damage of the stratosphere ozone layer in turn causes an increase in UV-B
exposure that leads to an increase of ion leakage, membrane protein oxidation, loss
of photosynthetic efficiency, and ultimately global yield loss. Longer and severe
stress episodes result in production of redox active molecules that in turn result in
oxidation of proteins, lipids, and nucleic acids [4].
Given the sessile nature, plants have developed more complex mechanisms
to sense and respond against the given stress condition. Plants respond to stress by
activating tolerance mechanisms by perception and transmission of stress signals
followed by a series of responses at multiple levels like morphological, physiological, biochemical, molecular, and anatomical adjustments [4]. These metabolic
adjustments ultimately decide the stress tolerance or stress susceptibility of the
plants. Although each stress induce a distinct defense response in plants, it is
essential to understand the complete mechanism of plant defense to individual
as well as stress in combination. Indeed in natural environments, plants may also
be subjected to multiple stress responses at a time. Abiotic stresses disrupt the
cellular redox homeostasis which leads to the oxidative stress or the generation of
reactive oxygen species (ROS) [1]. Different plant groups may respond differently
to the given stress dependent on the species, tolerance level, developmental stage,
25 Nitric Oxide as a Signal in Inducing Secondary Metabolites During Plant Stress
595
Nitrite reductase
O 3
Ozone
PAL
Phenylalanine ammonia-lyase
Pb
Lead
PCD
Programmed cell death
POD
Peroxidase
PSII
Photosystem II
PTMs
Posttranslational protein modifications
ROS
Reactive oxygen species
SNP
Sodium nitroprusside
SOD
Superoxide dismutase
ZN
Zinc
1
Introduction
Abiotic stress is defined as the harmful impact that nonliving factors including
environment factors exert on the living systems such as plants and animals growing
in the specific vicinity. Both plants and animals have evolved distinct mechanisms
to survive abiotic stress imposed due to extreme climate. Plant survival is often
challenged by a variety of different abiotic stress factors including drought, temperature extremes, heavy metals and salinity in soil, wounding, ozone, and UV-B stress.
Water deficit and high temperatures are perhaps the two major abiotic stresses which
are detrimental to crop growth and yield worldwide [1, 2]. Salts and heavy metal
accumulation in soil is also prevailing in crop lands. Furthermore, recent years have
seen the raising surface O 3 levels due to urbanization and industrial revolution which
has also become toxic both for human health and vegetation [3]. On the other hand,
the damage of the stratosphere ozone layer in turn causes an increase in UV-B
exposure that leads to an increase of ion leakage, membrane protein oxidation, loss
of photosynthetic efficiency, and ultimately global yield loss. Longer and severe
stress episodes result in production of redox active molecules that in turn result in
oxidation of proteins, lipids, and nucleic acids [4].
Given the sessile nature, plants have developed more complex mechanisms
to sense and respond against the given stress condition. Plants respond to stress by
activating tolerance mechanisms by perception and transmission of stress signals
followed by a series of responses at multiple levels like morphological, physiological, biochemical, molecular, and anatomical adjustments [4]. These metabolic
adjustments ultimately decide the stress tolerance or stress susceptibility of the
plants. Although each stress induce a distinct defense response in plants, it is
essential to understand the complete mechanism of plant defense to individual
as well as stress in combination. Indeed in natural environments, plants may also
be subjected to multiple stress responses at a time. Abiotic stresses disrupt the
cellular redox homeostasis which leads to the oxidative stress or the generation of
reactive oxygen species (ROS) [1]. Different plant groups may respond differently
to the given stress dependent on the species, tolerance level, developmental stage,
25 Nitric Oxide as a Signal in Inducing Secondary Metabolites During Plant Stress
595