Antioxidative response mechanisms in halophytes: Their role in stress defence

Abstract

Normal growth and development of plants is greatly dependent on the capacity to overcome environmental stresses. Environmental stress conditions like high salinity, drought, high incident light and low or high temperature cause major crop losses worldwide. A common denominator in all these adverse conditions is the production of reactive oxygen species (ROS) within different cellular compartments of the plant cell. Plants have developed robust mechanisms including enzymatic or nonenzymatic scavenging pathways to counter the deleterious effects of ROS production. There are a number of general reviews on oxidative stress in plants and few on the role of ROS scavengers during stress conditions. Here we review the regulation of antioxidant enzymes during salt stress in halophytes, especially mangroves. We conclude that (i) antioxidant enzymes protect halophytes from deleterious ROS production during salt stress, and (ii) genetic information from mangroves and other halophytes would be helpful in defining the roles of individual isoforms. This information would be critical in using the appropriate genes for oxidative stress defence for genetic engineering of enhanced stress tolerance in crop systems.

Antioxidant Enzyme Activities as a Tool to Discriminate Ecotypes of Crithmum maritimum L. Differing in Their Capacity to Withstand Salinity

“…In plants, scavenging of superoxides occurs by differential regulation of SOD isoforms (Wang et al, 2004). Studies on regulation of individual isoforms of SOD are therefore important because their role during salt stress could be elucidated (Jithesh et al, 2006). However, all the previous reports reflect the effect of NaCl stress on total SOD activity.…”

“…Recently, many authors addressed investigations on naturally salt tolerant plants (or halophytes) in which the mechanisms of salt tolerance are fully developed and functional to make them productive under stress. Jithesh et al (2006) reviewed the regulation of antioxidant enzymes under salt stress in halophytes, especially those of mangroves. They concluded that antioxidant enzymes protect halophytes from deleterious ROS production during salt stress.…”

Phytochemical composition of some common coastal halophytes of the United Arab Emirates

“…Stress response mechanisms in halophytes have been reviewed by Jithesh et al (2006). They note that salt stress, which affects cellular membranes, enzyme activities and the photosyntethic system, is largely caused by the damage from the production of reactive oxygen species (ROS) (Jithesh et al, 2006).…”

“…They note that salt stress, which affects cellular membranes, enzyme activities and the photosyntethic system, is largely caused by the damage from the production of reactive oxygen species (ROS) (Jithesh et al, 2006). Plants have evolved two antioxidative pathways to combat damage from ROS: an enzymatic pathway, which involves enzymes such as super oxide dismutase, and catalase, and a nonenzymatic pathway which includes antioxidants such as tocopherol, carotenoids, ascorbate, phenolic compounds, alkaloids, glutathione and non-protein amino acids that scavenge free radicals (Gill and Tuteja, 2010).…”

“…Plants have evolved two antioxidative pathways to combat damage from ROS: an enzymatic pathway, which involves enzymes such as super oxide dismutase, and catalase, and a nonenzymatic pathway which includes antioxidants such as tocopherol, carotenoids, ascorbate, phenolic compounds, alkaloids, glutathione and non-protein amino acids that scavenge free radicals (Gill and Tuteja, 2010). Jithesh et al (2006) also noted that osmolytes, such as glycine betaine and proline, which are produced by halophytes to adjust osmotically to saline conditions, may also provide protection against free radicals, but that the mechanism by which they confer protection is mostly unknown.…”