[Involvement of nitric oxide in regulation of salt stress-induced ABA accumulation in maize seedling]

Possible regulation of salt stress-induced ABA accumulation by nitric oxide (NO) in maize seedling was investigated. Both NO and ABA contents of maize leaves and root tips were increased in response to salt stress (Fig.1,2). Similar to the effects of salt stress, ABA contents of maize leaves and root tips were increased after the treatment of maize leaves with sodium nitroprusside (SNP, a nitric oxide donor) alone (Fig.3). Compared to the salt stress-induced ABA accumulation, this SNP-induced ABA increase was much faster, suggesting that NO may be an intermediate signal from salt stress to ABA accumulation. When NO production inhibitors L-NAME and NaN(3) treatments were applied, salt stress-induced ABA accumulation was lowered (Fig.4). Treatment with NO scavenger cPTIO also inhibited the salt stress-induced ABA increase (Fig.5). From these results it is deduced that NO is involved in regulation of ABA accumulation under salt stress.