molecule for ABA-induced stomatal closure, it has not been shown to be a signalling molecule for ABA inhibition of
stomatal opening. The NO scavenger cPTIO has been widely used to study the involvement of NO in plant and
animal cell processes. However, Planchet et al. (2006)recently cast doubt on the specificity of cPTIO as a NO
scavenger. Cryptogenin-induced cell death in tobacco leaves was efficiently prevented by cPTI (reaction product
of cPTIO and NO) without scavenging NO.