GLK-8903 REDUCES MEMBRANE PHOSPHOLIPID PEROXIDATION AND ALLEVIATES CHILLING INJURY IN PHASEOLUS-VULGARIS L

Twenty-day-old 'Bush Blue Lake 47' common bean plants grown in a growt h chamber at 25 days/22C night and a 12-hour photoperiod regime were f oliar sprayed with 0.5% GLK-8903 including 0.05% Tween-20. After 24 ho urs of treatment, plants were chilled in a cold room (4C day/night, 12 hours of light). After 3 days of chilling, leaves of untreated contro ls were injured, as visually characterized by leaf wilting, whereas le aves of the GLK-8903-treated plants still retained turgor. During chil ling, the activity of superoxide dismutase (SOD), peroxidase (POD), an d catalase (CAT) decreased. GLK-8903 treatment had no effect on SOD an d POD activities; however, the CAT activity was reduced significantly after GLK-8903 treatment either at 25 or at 4C. During chilling, the c ontent of malondialdehyde, a decomposition product of phospholipid per oxidation, increased in treated plants and untreated controls, with in creased content significantly lower in the former compared with the la tter. The GLK-8903 per se and total lipid extracted from GLK-8903-trea ted plants were able to reduce the linoleic acid oxidation in vitro. T he mechanism by which GLK-8903 alleviates chilling injury in bean plan ts is discussed.