Variable patterns of antioxidant protection but similar ethene emission differences in several ozone‐sensitive and ozone‐tolerant plant selections

Abstract

Six pairs of O3‐sensitive and O3‐tolerant cultivars, clones or populations of different plants (tobacco, plantain, clover, radish, poplar and loblolly pine) were taken through identical but short episodic exposures to O3 in a controlled‐environment fumigation system. Emissions of ethene and concentrations of polyamines, total phenols and ascorbate as well as levels of reduced glutathione and ascorbate in fumigated and clean air controls were determined in these various cultivars, clones and populations. A large number of significant differences were detected between the various sensitive and tolerant pairs, but it is clear that different sequences of response involving these parameters occur in these various plant pairs to account for their individual O3 sensitivity or tolerance. Some O3‐tolerant plants have increased polyamines, others total phenols and some appear to be able to form reduced ascorbate and glutathione more rapidly. In the case of ethene emissions, however, all O3‐sensitive selections produce more ethene when fumigated while O3‐tolerant ones either reduce their rates of emissions below those of clean air‐grown controls or at least keep them at the same level.

Ozone induction of ethylene emission in tomato plants: regulation by differential accumulation of transcripts for the biosynthetic enzymes

“…This role of ethylene has been elaborated in two tobacco cultivars of differential ozone sensitivity (Langebartels et al, 1991) and recently in several ozonetolerant and -sensitive plant selections (Wellburn and Wellburn, 1996). It was found that ethylene emission was the only consistent parameter in all systems showing significant increases in sensitive plants and no changes or even reduction below that of controls in ozone-tolerant selections (Wellburn and Wellburn, 1996).…”

The physiology of ozone induced cell death

“…Senescence is a complex and highly regulated process that mobilizes the nutrient components to other parts of the plant, and is usually considered to be a specialized form of PCD (Quirino et al 2000). Ethylene is widely known to modulate organ senescence induced by various stress factors such as plant pathogens (Moore et al 2000), O 3 (Wellburn and Wellburn 1996;Pell et al 1997) and hypoxia (He et al 1996). Since O 3 exposure induces ethylene and causes several morphological and physiological changes often associated with senescence, Pell et al (1997) have suggested that O 3 exposure reduces plant productivity by activating a slow cell death process referred to as``premature senescence.''…”

Inward Potassium Channel in Guard Cells As a Target for Polyamine Regulation of Stomatal Movements

“…Air pollution has been correlated with elevated polyamine levels in plants as well. Plants respond to pollutants such as ozone and SO 2 by producing high levels of polyamines (Priebe et al, 1978;Kramer et al, 1991;Wellburn and Wellburn, 1996). In all these studies, polyamine concentrations in plant tissues increase from high micromolar (under normal conditions) to millimolar range upon stress treatments.…”