Putrescine protects hulless barley from damage due to UV-B stress via H2S- and H2O2-mediated signaling pathways

Abstract

In hulless barley, H 2 S mediated increases in H 2 O 2 induced by putrescine, and their interaction enhanced tolerance to UV-B by maintaining redox homeostasis and promoting the accumulation of UV-absorbing compounds. This study investigated the possible relationship between putrescence (Put), hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) as well as the underlying mechanism of their interaction in reducing UV-B induced damage. UV-B radiation increased electrolyte leakage (EL) and the levels of malondialdehyde (MDA) and UV-absorbing compounds but reduced antioxidant enzyme activities and glutathione (GSH) and ascorbic acid (AsA) contents. Exogenous application of Put, H2S or H2O2 reduced some of the above-mentioned negative effects, but were enhanced by the addition of Put, H2S and H2O2 inhibitors. Moreover, the protective effect of Put against UV-B radiation-induced damage to hulless barley was diminished by DL-propargylglycine (PAG, a H2S biosynthesis inhibitor), hydroxylamine (HT, a H2S scavenger), diphenylene iodonium (DPI, a PM-NADPH oxidase inhibitor) and dimethylthiourea (DMTU, a ROS scavenger), and the effect of Put on H2O2 accumulation was abolished by HT. Taken together, as the downstream component of the Put signaling pathway, H2S mediated H2O2 accumulation, and H2O2 induced the accumulation of UV-absorbing compounds and maintained redox homeostasis under UV-B stress, thereby increasing the tolerance of hulless barley seedlings to UV-B stress.

Hydrogen Sulfide: A Signal Molecule in Plant Cross-Adaptation

“…H 2 S began to decline with time, but it is overall significantly higher than that of the control (approximately 125 nmol g -1 FW) at 48 h of exposure. A similar trend was observed for LCD activity, which was corroborated by the application of DL -propargylglycine (PAG, an inhibitor of LCD) that resulted in complete inhibition of the H 2 S production and the accumulation of UV-absorbing compounds induced by UV-B radiation (Li et al, 2016). …”

“…Recently, Li et al (2016) found that UV-B radiation could induce H 2 S production in leaves of barley seedlings, reaching a peak of approximately 230 nmol g - 1 FW after 12 h of exposure, which in turn promoted the accumulation of UV-absorbing compounds flavonoids and anthocyanins. H 2 S began to decline with time, but it is overall significantly higher than that of the control (approximately 125 nmol g -1 FW) at 48 h of exposure.…”

nduction of plant cells heat resistance by hydrogen sulfide donor is mediated by H(2)O(2) generation with participation of NADPH oxidase and superoxide dismutase

“…However, in the literature, we were able to find only indirect indications of the role of NADPH oxidase in ROS generation during the treatment of barley leaves with sodium hydrosulfide [12].…”

“…As was noted, in only one work, using inhibitor of NADPH oxidase diphenyleniodonium, the possible participation of this enzyme as an ROS generator was shown when inducing the resistance of barley plants to the action of UV-B [12] by the exogenous hydrogen sulfide. In our work using the inhibitory method, the causal relationship between hydrogen sulfidestimulated and NADPH oxidase dependent superoxide anion radical generation, induction of antioxidant enzymes, and development of heat resistance of wheat coleoptiles was first demonstrated.…”

“…Increasing resistance of barley plants to UV-B by hydrogen sulfide donor was accompanied by an increase in content of hydrogen peroxide in leaves and this effect was eliminated by the H 2 O 2 scavenger dimethylthiourea [12]. We have previously shown that induced by the hydrogen sulfide donor NaHS increase in heat resistance of wheat coleoptiles was leveled by treatment with an antioxidant ionol [13].…”