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

Abstract

High performance liquid chromatography analyses revealed that glu- tathione (GSH) and cysteine are two of the major low molecular weight Ihiol 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 ('''Sjcysteine showed lhat the rate of incorporation of o"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.