SIGNAL CROSSTALK BETWEEN NITRIC OXIDE AND HYDROGEN SULFIDE] MAY BE INVOLVED IN HYDROGEN PEROXIDE-INDUCED THERMOTOLERANCE IN MAIZE SEEDLINGS1

摘要

Hydrogen peroxide (Н_20_2) and nitric oxide (NO) function as signal molecules in plant cells. Recently, hydrogen sulfide (H2S) has been found to have similar functions, but their interactions in the acquisition of ther-motolerance in plants remain elusive. In current work, pretreatment with Н_20_2 rapidly induced endogenous Н_20_2 accumulation, which in turn improved survival percentage of maize seedlings (Zea mays L.) under heat stress, but these effects were eliminated by Н_20_2 scavenger dimethylthiourea (DTMU), indicating that Н_20_2-induced thermotolerance was involved in the accumulation of endogenous Н_20_2. Н_20_2 pretreatment also increased endogenous NO content, but this increase was abolished by NO scavenger cPTIO. Exogenous-ly applied Н_20_2 also stimulated increase in the activity of L-cystine desulfhydrase, a key enzyme in H2S biosynthesis, followed by inducing endogenous H2S accumulation, while this accumulation was diminished by cPTIO. In addition, Н_20_2-induced thermotolerance was enhanced by NO donor sodium nitroprusside (SNP) and H2S donors NaHS as well as GYY4137, respectively, and weakened by cPTIO, DL-propargylgly-cine (PAG, inhibitor of H2S biosynthesis) and hypotaurine (HT, H2S scavenger). All of the above-mentioned results showed that Н_20_2 treatment could improve thermotolerance in maize seedlings, and the acquisition of thermotolerance induced by Н_20_2 may be involved in downstream signal crosstalk between NO and H2S.