H2O2/ABA signal pathway participates in the regulation of stomata
opening of cucumber leaves under salt stress by putrescine
The stomatal-aperture is imperative for plant physiological metabolism.
The function of polyamines (PAs) in stomatal regulation under stress
environment largely remains elucidate. Herein, we investigated the
regulatory mechanism of exogenous putrescine (Put) on the stomatal
opening of cucumber leaves under salt stress. The results revealed that
Put relieved the salt-induced photosynthetic inhibition of cucumber
leaves by regulating stomatal-apertures. Put application increased
hydrogen peroxide (H2O2) and decreased abscisic acid (ABA) content in
leaves under salt stress. The inhibitors of diamine oxidase (DAO),
polyamine oxidase (PAO), nicotinamide adenine dinucleotide phosphate
oxidase (NADPH) are AG, 1,8-DO and DPI, respectively and pre-treatment
with these inhibitors up-regulated key gene NCED of ABA synthase and
down-regulated key gene GSHS of reduced glutathione (GSH) synthase. The
content of H2O2 and GSH were decreased and ABA content was increased and
its influenced trend is AG>1,8-DO>DPI.
Moreover, the Put induced down-regulation of ABA content under salt
stress blocked by treatment with H2O2 scavenger (DMTU) and GSH scavenger
(CNDB). Additionally, the application of DMTU also blocked the increase
of GSH content. Collectively, these results suggest that Put can
regulate GSH content by promoting H2O2 generation through polyamine
metabolic pathway, which inhibits ABA accumulation to achieve stomatal
regulation under salt stress.