ROLE OF GLUTATHIONE ON RECOVERY OF RED-OSIER DOGWOOD PLANTS FROM NEAR-LETHAL HEAT-STRESS

This study reports on the relationship of glutathione to the recovery and death of red-osier dogwood, Cornus sericea L., plants from ''near- lethal'' (NL) heat stress. Shoots of dormant red-osier dogwood plants were exposed to 51 degrees C for 1 h during early February, and then i ncubated in the dark at either 0 or 23 degrees C post-stress environme nt (PSE). In a previous study, NL heat stress treated plants incubated at 23 and 0 degrees C PSE recovered and died, respectively. Reduced a nd oxidized forms of glutathione (GSH and GSSG, respectively) were mea sured with HPLC at 365 nm absorbance after 0 h, 24 h, 2 weeks, and 4 w eeks PSE, respectively. Incubation of the NL heat stress treatments fo r 24 h at 23 +/- 3 degrees C prior to post-treatments resulted in a si gnificant decrease of GSSG and slight decrease of GSH. In contrast, th e sudden exposure of NL stressed plants to 0 degrees C for 24 h result ed in a significant reduction of both GSH and GSSG levels after 2 and 4 weeks incubation. At 23 degrees C PSE, GSH and GSSG levels of NL hea t stressed plants increased, while at 0 degrees C PSE the levels of bo th decreased.