Nitric Oxide and Reactive Oxygen Species Mediate Metabolic Changes in Barley Seed Embryo during Germination

Abstract

The levels of nitric oxide (NO) and reactive oxygen species (ROS), ATP/ADP ratios, reduction levels of ascorbate and glutathione, expression of the genes encoding proteins involved in metabolism of NO and activities of the enzymes involved in fermentation and in metabolism of NO and ROS were studied in the embryos of germinating seeds of two barley (Hordeum vulgare L.) cultivars differing in dormancy level. The level of NO production continuously increased after imbibition while the level of nitrosylated SH-groups in proteins increased. This corresponded to the decrease of free SH-groups in proteins. At early stage of germination (0–48 h post imbibition) the genes encoding class 1 phytoglobin (the protein scavenging NO) and S-nitrosoglutathione reductase (scavenging S-nitrosoglutathione) were markedly expressed. More dormant cultivar exhibited lower ATP/ADP and ascorbate/dehydroascorbate ratios and lower lactate and alcohol dehydrogenase activities, while the production of NO and nitrosylation of proteins was higher as compared to the non-dormant cultivar. The obtained data indicate that at the onset of germination NO is actively generated causing nitrosylation of SH-groups and a switch from respiration to fermentation. After radicle protrusion the metabolism changes in a more reducing type as recorded by ratio of reduced and oxidized glutathione and ascorbate. The turnover of NO by the scavenging systems (phytoglobin, S-nitrosoglutathione reductase and interaction with ROS) might contribute to the maintenance of redox and energy balance of germinating seeds and lead to alleviation of dormancy.

Involvement of nitrate reductase‐dependent nitric oxide production in magnetopriming‐induced salt tolerance in soybean

“…Similarly to NO, ROS are known as key players to control seed dormancy and germination (Song et al , Ma et al ). Sarath et al () demonstrated the strong link between ROS, ABA and NO in grass seeds germination and these authors also found that DPI inhibits the seed germination, because it inhibits activity of the NADPH oxidase enzyme that produce ROS.…”

Novel loci and a role for nitric oxide for seed dormancy and preharvest sprouting in barley

“…NO was highly abundant in nondormant genotypes and shared 69 loci with dormancy traits, indicative of a key role in dormancy alleviation. NO is generated from nitrate after imbibition by either nitrite reductase (Ma, Marsolais, Bykova, & Igamberdievi, 2016) or nonenzymatically in the aleuron cells (Bethke et al, 2007). NO is also stimulating both ethylene synthesis and signalling pathway (Arc, Sechet, Corbineau, Rajjou, & Marion-Poll, 2013).…”

Cross‐talk of Reactive Oxygen Species and Nitric Oxide in Various Processes of Plant Development

“…Examining the kinetics of the production of reactive species, ROS formation occurs during imbibition, while the generation of NO is induced by oxygen depletion later, upon germination. The work of Ma et al (2016) gives a deeper insight into the metabolism of NO during seed germination. The germinating seed produces NO, which consequently leads to the intensification of thiol nitrosylation.…”