Poster: Late and Moved Abstracts

Abs # 1373: Thermotolerance induction and endogenous changes of abscisic acid, salicylic acid, ethylene and hydrogen peroxide for creeping bentgrass during heat stress and recovery

Presenter:	Huang, Bingru , huang@aesop.rutgers.edu
Authors	Huang, Bingru  (A)   Larkindale, Jane  (A)
Affiliations:	(A): Rutgers University

Several chemicals such as abscisic acid (ABA), salicylic acid (SA), ethylene, and hydrogen peroxide (H2O2) may be involved in signal transduction during heat stress. The objectives of this study were to examine whether exogenous application of those chemicals or heat pre-treatment prior to heat stress (heat acclimation) can induce thermotolerance in a cool-season grass species, creeping bentgrass (Agrostis stolonifera) and to determine how the endogenous levels of these signaling components change during heat stress (35oC for 1 month) or recovery (20oC) from the stress. All of the pre-treatments (heat or chemical) resulted in increased tolerance to prolonged heat stress. This was manifested as higher turf quality, decreased membrane leakage, reduced oxidative damage, and higher chlorophyll contents than control plants given the same heat treatment. An oxidative burst was detected 5 minutes after the initiation of heat treatment, with the increase in H2O2 being detected primarily in the apoplast of the cells, and around the cell nuclei in both leaf and root tissues. Free SA was detected only an hour after the initiation of heat stress, and levels remained low thereafter. Neither ABA nor ethylene levels rose during heat stress, but levels of both increased during subsequent cooling. These results suggest that heat acclimation and chemical treatments induced thermotolerance in creeping bentgrass, but different chemicals may be involved in separate signaling pathways. An oxidative burst and SA may be bona fide heat stress signals, but ABA and ethylene appear to be involved in signaling pathways in response to recovery from heat stress in this species.