Hydrogen peroxide (H 2 O 2 ) and nitric oxide (NO) function as signal molecules in plant cells. Recently, hydrogen sulfide (H 2 S) has been found to have similar functions, but their interactions in the acqui sition of thermotolerance in plants remain elusive. In current work, pretreatment with H 2 O 2 rapidly induced endogenous H 2 O 2 accumulation, which in turn improved survival percentage of maize seedlings (Zea mays L.) under heat stress, but these effects were eliminated by H 2 O 2 scavenger dimethylthiourea indicating that H 2 O 2 induced thermotolerance was involved in the accumulation of endogenous H 2 O 2 . H 2 O 2 pretreatment also increased endogenous NO content, but this increase was abolished by NO scavenger cPTIO. Exogenously applied H 2 O 2 also stimulated increase in the activity of L cystine desulfhydrase, a key enzyme in H 2 S biosyn thesis, followed by inducing endogenous H 2 S accumulation, while this accumulation was diminished by cPTIO. In addition, H 2 O 2 induced thermotolerance was enhanced by NO donor sodium nitroprusside and H 2 S donors NaHS as well as GYY4137, respectively, and weakened by cPTIO, DL propargylglycine (inhibitor of H 2 S biosynthesis) and hypotaurine (H 2 S scavenger). All of the above mentioned results showed that H 2 O 2 treatment could improve thermotolerance in maize seedlings, and the acquisition of thermotolerance induced by H 2 O 2 may be involved in downstream signal crosstalk between NO and H 2 S.

No abstract