Different Effects of Reactive Species Generated from Chemical Donors on Seed Germination, Growth, and Chemical Contents of Oryza sativa L.

Reactive oxygen and nitrogen species (RONS) play an important role as signaling molecules in redox reactions throughout a plant life cycle. The purpose of this study was to assess how hydrogen peroxide (H2O2), a reactive oxygen species (ROS) and reactive nitrogen species (RNS) generated from sodium nitroprusside (SNP) and sodium nitrite, affects the germination, growth, and chemical contents of two rice cultivars (Pathum Tani and Sanpatong). The results showed that RNS generated from chemical donors and, especially, H2O2, enhanced the germination of the studied rice cultivars. Among the three chemical donors, H2O2 showed the best efficacy of the reactive species for activating early seed germination, followed by sodium nitrite and SNP. The highest percentage of seed germination rose to 99% at 6 h germination time after treatment with 25 mM of H2O2 for 24 h. Moreover, H2O2 produced a significant increase in the α-amylase activity and total soluble proteins. It was observed that a treatment with H2O2 on germinated seeds produced radicles with a dark blue color for longer than treatments with sodium nitrite and SNP. Our findings imply that H2O2 had a critical role in improving the germination and altering the chemical contents of rice seeds

Different Effects of Reactive Species Generated from Chemical Donors on Seed Germination, Growth, and Chemical Contents of <i>Oryza sativa</i> L.

Reactive oxygen and nitrogen species (RONS) play an important role as signaling molecules in redox reactions throughout a plant life cycle. The purpose of this study was to assess how hydrogen peroxide (H2O2), a reactive oxygen species (ROS) and reactive nitrogen species (RNS) generated from sodium nitroprusside (SNP) and sodium nitrite, affects the germination, growth, and chemical contents of two rice cultivars (Pathum Tani and Sanpatong). The results showed that RNS generated from chemical donors and, especially, H2O2, enhanced the germination of the studied rice cultivars. Among the three chemical donors, H2O2 showed the best efficacy of the reactive species for activating early seed germination, followed by sodium nitrite and SNP. The highest percentage of seed germination rose to 99% at 6 h germination time after treatment with 25 mM of H2O2 for 24 h. Moreover, H2O2 produced a significant increase in the α-amylase activity and total soluble proteins. It was observed that a treatment with H2O2 on germinated seeds produced radicles with a dark blue color for longer than treatments with sodium nitrite and SNP. Our findings imply that H2O2 had a critical role in improving the germination and altering the chemical contents of rice seeds

Non-thermal plasma treatment diminishes fungal viability and up-regulates resistance genes in a plant host.

Reactive oxygen and nitrogen species can have either harmful or beneficial effects on biological systems depending on the dose administered and the species of organism exposed, suggesting that application of reactive species can possibly produce contradictory effects in disease control, pathogen inactivation and activation of host resistance. A novel technology known as atmospheric-pressure non-thermal plasma represents a means of generating various reactive species that adversely affect pathogens (inactivation) while simultaneously up-regulating host defense genes. The anti-microbial efficacy of this technology was tested on the plant fungal pathogen Fusarium oxysporum f.sp. lycopersici and its susceptible host plant species Solanum lycopercicum. Germination of fungal spores suspended in saline was decreased over time after exposed to argon (Ar) plasma for 10 min. Although the majority of treated spores exhibited necrotic death, apoptosis was also observed along with the up-regulation of apoptosis related genes. Increases in the levels of peroxynitrite and nitrite in saline following plasma treatment may have been responsible for the observed spore death. In addition, increased transcription of pathogenesis related (PR) genes was observed in the roots of the susceptible tomato cultivar (S. lycopercicum) after exposure to the same Ar plasma dose used in fungal inactivation. These data suggest that atmospheric-pressure non-thermal plasma can be efficiently used to control plant fungal diseases by inactivating fungal pathogens and up-regulating mechanisms of host resistance

Effect of solution change and absorption spectroscopy analysis.

<p><b>A</b>, Relative spore germination after Ar plasma treatment and consecutive incubation without (left graph) or with (right panel) a solution change. The calculations for relative germination and statistical analysis were performed as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099300#pone-0099300-g002" target="_blank">Figure 2</a>. <b>B</b>, Absorption spectra of saline treated with Ar gas (control) or plasma for 1, 5, or 10 min and then incubated for 0 and 3 h. <b>C</b>, Relative spore germination in saline solution with the pH adjusted using nitric acid (HNO₃).</p

Mechanisms associated with spore death.

<p><b>A</b>, Relative comparisons of apoptotic and necrotic death indicated by the percentage of Annexin V and PI stained spores following Ar plasma treatment over time. <b>B</b>, Image of spores stained with Annexin V and PI after a 10 min plasma treatment. <b>C</b>, Proportion of spores stained with Annexin V and PI analyzed by flow cytometry. Spores were treated with Ar plasma in saline for 10 min and then incubated for 0, 2, and 4 h. <b>D</b>, mRNA expression levels of the apoptosis related genes Dnm, Meta1, 2, and AIF1, 2 were analyzed by real time RT-PCR. Spores were treated with Ar plasma in saline for 10 min and then incubated for 0 and 2 h. Each value represents the average of 3 replicate measurements. *p<0.05 and **p<0.01; Student's <i>t</i> test. <b>E</b>, Spores treated with plasma for 10 min were subjected to TUNEL assay. Fungal spores treated with farnesol (0.5 mM) to induce apoptosis <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099300#pone.0099300-Oehmigen1" target="_blank">[47]</a> were used as a positive control.</p

Germination of fungal spores after plasma treatment.

<p>Relative germination of <i>F. oxysporum f.sp.lycopersici</i> spores was assessed after air and argon plasma treatment in PBS or saline. The relative spore germination percent was calculated as follows: (number of germinated spores treated with plasma/number of germinated spores treated with gas only) x 100. *p<0.05 and **p<0.01; Student's <i>t</i> test.</p