Nitrate- and nitric oxide-induced plant growth in pea seedlings is linked to antioxidative metabolism and the ABA/GA balance

Abstract

This study looks at the effects of potassium nitrate (KNO) and sodium nitroprusside (SNP), a nitric oxide (NO)-donor, on the development, antioxidant defences and on the abscisic acid (ABA) and gibberellin (GA) levels in pea seedlings. Results show that 10 mM KNO and 50 μM SNP stimulate seedling fresh weight (FW), although this effect is not reverted by the action of 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a NO-scavenger. The KNO treatment increased peroxidase (POX) and ascorbate oxidase (AOX) activities. SNP, on the other hand, reduced monodehydroascorbate reductase (MDHAR) activity and produced a significant increase in superoxide dismutase (SOD), POX and AOX activities. The "KNO plus cPTIO" treatment increased ascorbate peroxidase (APX), MDHAR, glutathione reductase (GR) and SOD activities, but POX activity decreased in relation to the KNO treatment. The "SNP plus cPTIO" treatment increased APX and MDHAR activities, whereas a huge decrease in POX activity occurred. Both the KNO and the SNP treatments increased reduced ascorbate (ASC) concentrations, which reached control values in the presence of cPTIO. All treatments increased the dehydroascorbate (DHA) level in pea seedlings, leading to a decrease in the redox state of ascorbate. In the "KNO plus cPTIO" treatment, an increase in the redox state of ascorbate was observed. Glutathione contents, however, were higher in the presence of SNP than in the presence of KNO. In addition, KNO produced an accumulation of oxidised glutathione (GSSG), especially in the presence of cPTIO, leading to a decrease in the redox state of glutathione. The effect of SNP on reduced glutathione (GSH) levels was reverted by cPTIO, suggesting that NO has a direct effect on GSH biosynthesis or turnover. Both the KNO and SNP treatments produced an increase in GA4 and a decrease in ABA concentrations, and this effect was reverted in the presence of the NO-scavenger. Globally, the results suggest a relationship between antioxidant metabolism and the ABA/GA balance during early seedling growth in pea. The results also suggest a role for KNO and NO in the modulation of GA4 and ABA levels and antioxidant metabolism in pea seedlings. Furthermore, this effect correlated with an increase in the biomass of the pea seedlings.

Potassium Nitrate Treatment Is Associated with Modulation of Seed Water Uptake, Antioxidative Metabolism and Phytohormone Levels of Pea Seedlings

“…Potassium nitrate (KNO 3 ) has been demonstrated to break seed dormancy, promote seed germination and enhance growth uniformity in a variety of plant species, including tomato, maize, Arabidopsis and pea [9][10][11][12]. However, the mechanism by which KNO 3 improves seed germination and seedling establishment remains unclear.…”

“…Lincoln) displayed reduced germination and seedling growth when incubated for three days in the presence of 30 or 40 mM KNO 3 , whereas 10 mM KNO 3 stimulated early seedling growth. However, when the pea seeds were imbibed with KNO 3 (40 mM) for 24 h and then incubated in distilled water, seedling fresh weight was enhanced, whereas germination rate remained Seeds 2021, 1 6 unchanged [12]. Other authors [14] suggested that nitrates may enhance seed germination and early seedling growth due to the dual role of N as a plant essential element for growth and as a signalling molecule.…”

Impacts of LEDs in the Red Spectrum on the Germination, Early Seedling Growth and Antioxidant Metabolism of Pea (Pisum sativum L.) and Melon (Cucumis melo L.)

“…Recently, it has been reported that melon plants treated with blue light or the combination red-blue light (3:1) increased the tolerance to powdery mildew, whereas the combination red-blue light increased plant growth [23]. Regarding pea seeds, recent works described that H 2 O 2 -priming increased the germination rate as well as the early seedling growth [10], whereas KNO 3 treatments modulated the levels of the plant hormones GA 4 and ABA, this response being correlated with an increase in the biomass of pea seedlings [24].…”

Seed Science Research: Global Trends in Seed Biology and Technology

“…Both KNO 3 and sodium nitroprusside (SNP), a nitric oxide (NO)-donor, stimulated early seedling growth. Both treatments reduced ABA concentrations and induced the GA 4 levels in pea seedlings, thus resulting in a strong decrease in the ABA/GA ratio [12].…”

“…ROSs, such as nitric oxide (NO), in addition to different nitrogen-containing compounds, including nitrite, nitrate and sodium nitroprusside (SNP, a NO-generating compound), have also been associated with seed dormancy breaking and the germination process [4,11,12]. Both KNO 3 and sodium nitroprusside (SNP), a nitric oxide (NO)-donor, stimulated early seedling growth.…”