AUTHOR=Wang Weiling , Wang Xiao , Huang Mei , Cai Jian , Zhou Qin , Dai Tingbo , Cao Weixing , Jiang Dong 

TITLE=Hydrogen Peroxide and Abscisic Acid Mediate Salicylic Acid-Induced Freezing Tolerance in Wheat

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01137

DOI=10.3389/fpls.2018.01137

ISSN=1664-462X

ABSTRACT=<p>Salicylic acid (SA) can induce plant resistance to biotic and abiotic stresses through cross talk with other signaling molecules, whereas the interaction between hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and abscisic acid (ABA) in response to SA signal is far from clear. Here, we focused on the roles and interactions of H<sub>2</sub>O<sub>2</sub> and ABA in SA-induced freezing tolerance in wheat plants. Exogenous SA pretreatment significantly induced freezing tolerance of wheat via maintaining relatively higher dark-adapted maximum photosystem II quantum yield, electron transport rates, less cell membrane damage. Exogenous SA induced the accumulation of endogenous H<sub>2</sub>O<sub>2</sub> and ABA. Endogenous H<sub>2</sub>O<sub>2</sub> accumulation in the apoplast was triggered by both cell wall peroxidase and membrane-linked NADPH oxidase. The pharmacological study indicated that pretreatment with dimethylthiourea (H<sub>2</sub>O<sub>2</sub> scavenger) completely abolished SA-induced freezing tolerance and ABA synthesis, while pretreatment with fluridone (ABA biosynthesis inhibitor) reduced H<sub>2</sub>O<sub>2</sub> accumulation by inhibiting NADPH oxidase encoding genes expression and partially counteracted SA-induced freezing tolerance. These findings demonstrate that endogenous H<sub>2</sub>O<sub>2</sub> and ABA signaling may form a positive feedback loop to mediate SA-induced freezing tolerance in wheat.</p>