2 research outputs found
The Alleviation of the Adverse Effects of Salt Stress in the Tomato Plant by Salicylic Acid Shows A Time- and Organ-Specific Antioxidant Response
In the last decade contradictory results have been published as to whether exogenous salicylic acid (SA) can
increase salt stress tolerance in cultivated plants by inducing an antioxidant response. Salt stress injury in tomato
was mitigated only in cases when the plant was hardened with a high concentration of SA (~10-4 M), low concentrations
were ineffective. An efficient accumulation of Na+ in older leaves is a well-known response to salt
stress in tomato plants (Solanum lycopersicum cv. Rio fuego) but it remains largely unexplored whether young
and old leaves or root tissues have a distinct antioxidant status during salt stress after hardening with 10-7 M or
10-4 M SA. The determination of superoxide dismutase (SOD) and catalase (CAT) activity revealed that the SAinduced
transient increases in these enzyme activities in young leaf and/or root tissues did not correlate with the
salt tolerance of plants. Salt stress resulted in a tenfold increase in ascorbate peroxidase (APX) activities of young
leaves and significant increases in APX and glutathione reductase (GR) activities of the roots hardened with
10-4 M SA. Both total ascorbate (AsA) and glutathione pools reached their highest levels in leaves after 10-7 M
SA pre-treatment. However, in contrast to the leaves, the total pool of AsA decreased in the roots under salt
stress and thus, due to low APX activity, active oxygen species were scavenged by ascorbate non-enzymatically
in these tissues. The increased GR activities in the roots after treatment with 10-4 M SA enabled plants to
enhance the reduced glutathione (GSH) pool and maintain the redox status of AsA under high salinity, which led
to increased salt tolerance
Involvement of Selenium in Protective Mechanisms of Plants under Environmental Stress Conditions – Review
In recent years there has been growing interest in selenium (Se) as an important micronutrient not only for animals
and humans but also for plants. In particular, its protective effect in plants exposed to stress conditions
has been suggested. In spite of many studies, the mechanism of Se action is not fully understood. In this review,
possible ways of interaction of Se with stress factors leading to optimal growth and development of plants are
presented. As the majority of experiments have focused on the effects of Se application under stress conditions
induced by heavy metals, special attention is paid to the results obtained in such studies. Changes of physiological
and biochemical properties of plant cells, with particular regard to the influence of Se on the activation
of enzymatic and non-enzymatic antioxidants under this stress, are summarized. Experiments in which Se was
used in some other environmental stresses (drought, UV, cold and high temperature) are also cited. On the basis
of the presented literature it is suggested that a positive effect of Se depends on both its doses and on chosen
plant genotypes and is mainly connected with activation of antioxidative defense in plant cells