Calcium and Calmodulin Are Involved in Nitric Oxide-Induced Adventitious Rooting of Cucumber under Simulated Osmotic Stress

Abstract

Osmotic stress is a major form of abiotic stress that adversely affects growth and development of plants and subsequently reduces yield and quality of crops. In this study, the effect of nitric oxide (NO) and calcium (Ca2+) on the process of adventitious rooting in cucumber (Cucumis sativus L.) under simulated osmotic stress was investigated. The results revealed that the effect of exogenous NO and Ca2+ in promoting the development of adventitious roots in cucumber seedlings under simulated osmotic stress was dose-dependent, with a maximal biological response at 10 μM NO donor nitroprusside (SNP) or 200 μM Ca2+. The application of Ca2+ chelators or channel inhibitors and calmodulin (CaM) antagonists significantly reversed NO-induced adventitious rooting, implying that endogenous Ca2+/CaM might be involved in NO-induced adventitious rooting under osmotic stress. Moreover, intracellular Ca amount was also increased by NO in cucumber hypocotyls during the development of adventitious roots under osmotic stress. This increase of endogenous Ca2+ was inhibited by NO specific scavenger 2-(4-carboxyphenyl) -4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO), nitrate reductase inhibitors tungstate (Na2WO4) and sodium azide (NaN3). This gives an indication that Ca2+ might be a downstream signaling molecule in the adventitious root development by NO under osmotic condition. The results also show that NO or Ca2+ play a positive role in improving plant water status and photosynthetic system by increasing chlorophyll content and photochemical activity in leaves. Furthermore, NO and Ca2+ treatment might alleviate the negative effects of osmotic stress by decreasing membrane damage and reactive oxygen species (ROS) production by enhancing the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Therefore, Ca2+/CaM may act as a downstream signaling molecule in NO-induced development of adventitious root under simulated osmotic stress through improving the photosynthetic performance of leaves and activating antioxidative system in plants.

Involvement of Calcium and Calmodulin in Nitric Oxide-Regulated Senescence of Cut Lily Flowers

“…Our results further show that Ca 2+ /CaM might be involved in the NO-regulated postharvest freshness process of cut lily flowers. The earlier reports about other plants, including cucumber ( Niu et al, 2017 ), fava bean ( Zhao et al, 2013 ), grape ( Vandelle et al, 2006 ), tobacco ( Lamotte et al, 2006 ), Arabidopsis ( Abdul-Awal et al, 2016 ), tall fescue ( Xu et al, 2016 ), tomato ( Siddiqui et al, 2017 ), wheat ( Tian et al, 2015 ), rice ( Chen and Kao, 2012 ), and marigold ( Liao et al, 2012b ), are in conformity with our results, suggesting there are intricate interplays between NO and Ca 2+ .…”

“…The results indicate that Ca 2+ was involved in the NO-related postharvest freshness, and the positive effect of NO might depend on increased Ca 2+ content ( Figure 6 ), at least partly. Recent studies from our laboratory have shown that intracellular Ca 2+ amount was increased by NO in cucumber hypocotyls during the development of adventitious roots under osmotic stress ( Niu et al, 2017 ). These results are in full agreement with the findings of Siddiqui et al (2017) , who found that exogenous NO and Ca 2+ applied individually as well as in combination significantly enhanced of Ca 2+ content under both heat stress and non-stress conditions.…”

“…Each treatment was conducted in three replications. The concentrations of these chemicals were selected based on the result of a recent experiment conducted in our laboratory ( Niu et al, 2017 ). Fresh test solutions were made every day to replace the vase solutions which were made the day before.…”

“…The study on marigold indicate that exogenous NO promoted adventitious rooting by increasing endogenous Ca 2+ and CaM levels ( Liao et al, 2012b ). In addition, the involvement of Ca 2+ /CaM in NO-induced adventitious rooting in cucumber under simulated osmotic stress has also been studied ( Niu et al, 2017 ). Thus, Ca 2+ appears to be both upstream and downstream of NO signaling during plant growth and stress responses.…”

iTRAQ-Based Proteomic Analysis Reveals Potential Regulation Networks of IBA-Induced Adventitious Root Formation in Apple

“…Nitric oxide (NO) has also been shown to be involved in AR formation in many species [ 65 , 66 , 67 ]. Based on a previous study in cucumber explants, proteins extracted form plants with NO-donor sodium nitroprusside (SNP) and IAA-treatment showed an activity of protein kinase, which could be inhibited by mitogen-activated protein kinases (MAPKs) inhibitor.…”