NITRIC OXIDE IS INVOLVED IN ETHYLENE-INDUCED ADVENTITIOUS ROOT DEVELOPMENT IN CUCUMBER (CUCUMIS SATIVUS L.) EXPLANTS

Abstract

Both ethylene (ETH) and nitric oxide (NO) are endogenous signaling molecules that regulate plant adventitious root development. The relationship between ETH and NO in that process remains poorly understood. In this report, our results show that the effects of ETH on adventitious rooting in cucum ber (Cucumis Sativus L.) explants were dose-dependent, and 0.5 M ETH donor ethrel treatment was the most effective concentration to promote adventitious rooting. The positive effect of ETH could be reversed by NO scavenger 2-(4-carboxy-2-phenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (c PTIO),nitric oxide synthase (NOS)inhibitor N-nitro-l-argininemethyl ester (L-NAME) ornitrate reductase (NR) inhibitor NaN3, indicating that the ETH-induced response, at least partially, was NO-dependent. Meanwhile, the exposure of cucumber explants to ETH up-regulated NOS and NR activity and their gene relative expression. Moreover, molecular evidence indicated that ETH improved the expression of genes involved in adventitious root development, including DNAJ-like gene (CsDNAJ-1) and calcium-dependent protein kinase genes (CsCDPK1 and CsCDPK5). However, the effects of ETH were inhibited by c-PTIO, L NAME or NaN3. The results indicate that NO plays crucial role in the adventitious root development induced by ETH.