Iron‐catalysed oxygen radical formation and its possible contribution to drought damage in nine native grasses and three cereals

Abstract

Abstract. The origin, sequence and location of molecular damage arising during sub‐lethal drought is described in 4‐week‐old wheat (Triticum aestivum L.). Short episodes of water deprivation increased the uptake of iron within 6h of drought. Superoxide, precursor of the highly reactive hydroxyl radical in the presence of iron, was formed in the thylakoid membranes. Further draughting promoted destruction of chlorophylls (but not carotenoids), which was detectable after 14 h and preceded significant losses in relative water content. Peroxidation of lipids and a decreased protein content occurred after 26h of cumulative water deprivation but was confined to the shoots. In contrast, there was no significant loss of protein nor peroxidation of lipids in the root tissue, despite quantitatively larger, more rapid, losses in water content. These results indicate that damage arising in the early phases of drought appears to be initiated within the chloroplast and to be largely confined to the photosynthetic tissue. The pattern of drought‐induced damage in 11 other non‐xerophytes of the north temperate region was qualitatively similar to wheat, although the response to drought of the three cereals was more extreme than in the indigenous grasses and less extreme in ecologically stress‐tolerant species. A method for the simultaneous quantification of carotenoids in the presence of chlorophylls is provided.

Tansley Review No. 111

“…High levels of accumulation of Fe in plant or animal cells are responsible for the initiation of severe oxidative stress because they produce ROS by various cellular reactions (Halliwell & Gutteridge, 1984 ;Price & Hendry, 1991 ;Hendry, 1993 ;Becanne et al, 1998). Interestingly, the role of Fe in generating ROS and causing cellular damage in Zn-deficient plants has not been studied, and has only rarely been discussed in the literature.…”

Isolation, Chromosomal Localization, and Differential Expression of Mitochondrial Manganese Superoxide Dismutase and Chloroplastic Copper/Zinc Superoxide Dismutase Genes in Wheat1

“…Active oxygen species are also generated during chemical and environmental stresses, including chilling and freezing (Wise and Naylor, 1987;Senaratna et al, 1988;Kendall and McKersie, 1989;Tsang et al, 1991;McKersie et al, 1993), drought (Perl-Treves and Galun, 1991;Price and Hendry, 1991), desiccation (Senaratna et al, 1985;Leprince et al, 1990), flooding (Hunter et al, 1983;Van Toai and Bolles, 1991), herbicide treatment (Malan et al, 1990;Kurepa et al, 1997), pathogen attack (Montalbini and Buonaurio, 1986;Buonaurio et al, 1987;Koch and Slusarenko, 1990), and ionizing radiation (Niwa et al, 1977).…”

“…Cold and drought are the most common environmental stresses, but the regulation of SOD gene expression under these conditions is not well documented (Perl-Treves and Galun, 1991;Price and Hendry, 1991;McKersie et al, 1993). Wheat (Triticum aestivum) is the largest cultivated crop in the world and has distinct spring and winter genotypes.…”

“…Cu/ZnSOD is located mainly in the cytosol and/or chloroplasts of plants, whereas the other family contains either Mn (MnSOD) in the mitochondria or Fe (FeSOD) in the chloroplast (Fridovich, 1986). For monocotyledonous plants, only cDNAs for chloroplastic Cu/ ZnSOD and mitochondrial MnSOD have been isolated from rice or corn (Sakamoto et al, 1993;Zhu and Scandalios, 1993; Kaminaka et al, 1997).Cold and drought are the most common environmental stresses, but the regulation of SOD gene expression under these conditions is not well documented (Perl-Treves and Galun, 1991;Price and Hendry, 1991;McKersie et al, 1993). Wheat (Triticum aestivum) is the largest cultivated crop in the world and has distinct spring and winter genotypes.…”

A rapid change in ozone resistance of Plantago major after summers with high ozone concentrations

“…This is best illustrated by reference to drought. Episodes of ozone are associated with warm, sunny weather which might also lead to drought, which in turn might impose an oxidant stress (Price & Hendry, 1991) similar to that caused by ozone. If droughtresistant individuals in the population have a greater capacity to scavenge free-radicals or repair damage, then they might also be more ozone-resistant.…”