Effects of polyamines on the expression of antioxidant genes and proteins in citrus plants exposed to salt stress
Date Issued
2009
Abstract
Although there are accumulating reports that polyamines are involved in
abiotic/oxidative stress responses, their role is not yet fully understood. Salt stress is
one of the most devastating abiotic stresses which seriously interrupt plant growth and
productivity. The present study attempts to examine the effects of root treatments with
putrescine (Put, I mM), spermidine (Spd, ImM) and spermine (Spm, ImM) on
polyamine homeostasis, as well as on several antioxidant-related genes and proteins in
the leaves of citrus plants (Citrus aurantium L.) exposed to 150 mM NaCI for 15 d.
Analysis of endogenous levels of free polyarnines in NaCl-stressed plant tissues
reveals the existence of a polyamine transport system from roots to leaves. Real-time
analysis of reactive oxygen species (ROS) by confocal laser scanning microscopy
(CLSM) showed an over-accumulation of superoxide anion (02) and hydrogen
peroxide (H202) in the stomata of citrus plants exposed to salt stress. Exogenously
applied polyamines to salinized nutrient solution induced the activities of superoxide
dismutase (SOD), catalase (CAT), glutathione reductase (GR), dehydroascorbate
reductase (DHAR) and ascrobic oxidase (AO) whereas it caused the opposite effect
on peroxidase (POD), guaiacol peroxidase (GPO D) and ascorbate peroxidase (APX).
The effect of polyamines was further examined by determining the plant's antioxidant
gene expression profile following a quantitative real-time RT-PCR approach. The
overall results indicate that the interaction between different polyamines can be
dispersed throughout the citrus plant, and provide additional information suggesting
that polyamines may act as a biological mediator allowing citrus plants to activate
specific antioxidant responses against salinity
abiotic/oxidative stress responses, their role is not yet fully understood. Salt stress is
one of the most devastating abiotic stresses which seriously interrupt plant growth and
productivity. The present study attempts to examine the effects of root treatments with
putrescine (Put, I mM), spermidine (Spd, ImM) and spermine (Spm, ImM) on
polyamine homeostasis, as well as on several antioxidant-related genes and proteins in
the leaves of citrus plants (Citrus aurantium L.) exposed to 150 mM NaCI for 15 d.
Analysis of endogenous levels of free polyarnines in NaCl-stressed plant tissues
reveals the existence of a polyamine transport system from roots to leaves. Real-time
analysis of reactive oxygen species (ROS) by confocal laser scanning microscopy
(CLSM) showed an over-accumulation of superoxide anion (02) and hydrogen
peroxide (H202) in the stomata of citrus plants exposed to salt stress. Exogenously
applied polyamines to salinized nutrient solution induced the activities of superoxide
dismutase (SOD), catalase (CAT), glutathione reductase (GR), dehydroascorbate
reductase (DHAR) and ascrobic oxidase (AO) whereas it caused the opposite effect
on peroxidase (POD), guaiacol peroxidase (GPO D) and ascorbate peroxidase (APX).
The effect of polyamines was further examined by determining the plant's antioxidant
gene expression profile following a quantitative real-time RT-PCR approach. The
overall results indicate that the interaction between different polyamines can be
dispersed throughout the citrus plant, and provide additional information suggesting
that polyamines may act as a biological mediator allowing citrus plants to activate
specific antioxidant responses against salinity
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