Effect of Heat Shock on the Metabolism of Glutathione in Maize Roots

Abstract

ABSTRACT?High performance liquid chromatography analyses revealed that glutathione (GSH) and cysteine are two of the major low molecular weight thiol compounds in maize root extracts. Treatment of maize roots to heat shock temperatures of 40°C resulted in a decrease of cysteine levels and an increase of GSH levels. Pulse labeling of maize roots with [5Sjcysteine showed that the rate of incorporation of 3"S into GSH or glutathione disulfide (GSSG) in heat shocked tissues was twice that in nonheat shocked tissues. In addition, extracts from heat shocked maize, barley, and soybean tissues contained an unidentified low molecular weight compound that increased from 1.2-to 8-fold within 2 hours of heat shock treatment depending on the tissue and plant involved. Our results indicate that during heat shock there is an increase in the activity of the GSH synthetizing capacity in maize root cells. The elevated synthesis of GSH may be related to the cells capacity to cope with heat stress conditions.

Glutathione Causes a Massive and Selective Induction of Plant Defense Genes

“…Heavy metals have also been shown to stimulate the synthesis of phytoalexins in soybean cotyledons (17), and the effects of GSH on plant defense gene expression suggest a possible mechanism. Moreover, GSH plays a protective role in cellular metabolism by acting as a reductant to remove free radicals (16,20), and it has recently been shown that heat shock of maize roots elevates the cellular concentration of GSH (18). Oxidative reactions such as the release of superoxide anions and the peroxidation of lipids are early responses to mechanical damage and infection (4).…”

“…Functions proposed for glutathione in higher plants include: storage and transport of reduced sulfur; protein reductant; destruction of H202 in chloroplasts, and detoxification of xenobiotics including certain herbicides and pesticides (8,20). Overall, glutathione appears to play a key role in protection against oxidative damage arising from a number of stresses such as irradiation (16), heat (18), and exposure to heavy metals (10).…”

Acclimation to ozone stress in radish: leaf demography and photosynthesis

“…Ozone, along with other oxidative stresses (sulphur dioxide, low temperatures, heat-shock and drought), produces highly reactive free radicals at the surface of plant cell membranes (Nieto-Sotelo & Ho, 1986;Alscher & Amthor, 1988;Heath & Castillo 1988). Among the deleterious effects caused by prolonged exposure to ozone, the most noticeable at the plant level are leaf chlorosis and accelerated senescence (Reich & Lassoie, 1985).…”

Characterization of Glutathione Uptake in Broad Bean Leaf Protoplasts

“…destruction of H,O, in chloroplasts, in the detoxification of xenobiotics (Rennenberg, 1982;Edwards and Owen, 1986;Martinoia et al, 1993), and in protection against various stresses, such as irradiation (Meister and Anderson, 1983), heat (Nieto-Sotelo and Ho, 1986), oxidative stress dueto O, or SO, (Alscher, 1989), and exposure to heavy metals (Grill et al, 1985). Supply of GSH to suspension-cultured cells of bean stimulates the transcription of various defense genes, including those encoding cell wall Hyp-rich glycoproteins, phenylalanyl ammonia-lyase, and chalcone synthase (Wingate et al, 1988).…”