Sulphate induced accumulation of glutathione and frost-tolerance of spinach leaf tissue.

Water-extractable sulfhydryl content of spinach leaf discs increased up to four-fold when, they were incubated with sulphate (10-100 mM) for 20 h in light or darkness. The accumulated sulfhydryl compound was reduced glutathione. An increased glutathione content did not result in a higher frost-tolerance of the spinach leaf discs. Both freezing temperature and time of exposure to freezing, determined as the point at! which 50% of the cells were killed, remained unchanged after incubation with sulphate. These observations suggest that a sulfhydryl compound as glutathione does not play a direct role in protection of plants against freezing injury. [ABSTRACT FROM AUTHOR]