Dynamics of Reactive Carbonyl Species in Pea Root Nodules in Response to Polyethylene Glycol (PEG)-Induced Osmotic Stress

Abstract

Drought dramatically affects crop productivity worldwide. For legumes this effect is especially pronounced, as their symbiotic association with rhizobia is highly-sensitive to dehydration. This might be attributed to the oxidative stress, which ultimately accompanies plants’ response to water deficit. Indeed, enhanced formation of reactive oxygen species in root nodules might result in up-regulation of lipid peroxidation and overproduction of reactive carbonyl compounds (RCCs), which readily modify biomolecules and disrupt cell functions. Thus, the knowledge of the nodule carbonyl metabolome dynamics is critically important for understanding the drought-related losses of nitrogen fixation efficiency and plant productivity. Therefore, here we provide, to the best of our knowledge, for the first time a comprehensive overview of the pea root nodule carbonyl metabolome and address its alterations in response to polyethylene glycol-induced osmotic stress as the first step to examine the changes of RCC patterns in drought treated plants. RCCs were extracted from the nodules and derivatized with 7-(diethylamino)coumarin-3-carbohydrazide (CHH). The relative quantification of CHH-derivatives by liquid chromatography-high resolution mass spectrometry with a post-run correction for derivative stability revealed in total 194 features with intensities above 1 × 105 counts, 19 of which were down- and three were upregulated. The upregulation of glyceraldehyde could accompany non-enzymatic conversion of glyceraldehyde-3-phosphate to methylglyoxal. The accumulation of 4,5-dioxovaleric acid could be the reason for down-regulation of porphyrin metabolism, suppression of leghemoglobin synthesis, inhibition of nitrogenase and degradation of legume-rhizobial symbiosis in response to polyethylene glycol (PEG)-induced osmotic stress effect. This effect needs to be confirmed with soil-based drought models.

Signaling in Legume–Rhizobia Symbiosis

“…Indeed, the age-related enhancement of oxidative stress occurs at the background of high sugar concentrations present in nodules. This aspect was confirmed by analyzing the proteome and metabolome of nodules [196,197]. Thus, the age-related increase in protein glycation and lipoxidation can be expected in all plant organs including root nodules [196][197][198].…”

“…This aspect was confirmed by analyzing the proteome and metabolome of nodules [196,197]. Thus, the age-related increase in protein glycation and lipoxidation can be expected in all plant organs including root nodules [196][197][198]. It needs to be taken into account that due to high glycation potential of regulatory sugars and sugar-related molecules (fructose, sucrose, poly(ADP-ribose), sugar phosphates) [199], it can be assumed that glycation might be involved in regulation of plant stress response [198].…”

Drought Stress Response in Guar (Cyamopsis tetragonoloba (L.) Taub): Physiological and Molecular Genetic Aspects

“…The tolerance of legume plants to nutritional stresses cannot be addressed without consideration of the rhizosphere microbiome, the most important of which are root microsymbionts, dominating with nodule rhizobia bacteria [126]. It is well known that dehydration is accompanied by pronounced metabolic changes in legume nodules [127]. Nitrogen-fixation capacity of guar is estimated to reach 34 to 54 kg of nitrogen per ha of soil per year [128].…”

Sydnone Imines as a New Class of Promising Plant Growth and Stress Tolerance Modulators—A First Experimental Structure–Activity Overview

“…Enhanced RNS generation leads to posttranslational modifications such as oxidation, nitration, nitrosation and metal-and S-nitrosylation, the so-called nitrosative stress. Thus, oxidative, carbonyl and nitrosative stresses caused by unfavorable environmental conditions might have a potential for a relevant impact on the nutritional properties of plant proteins, a topic under current research [15][16][17]. In this context, preserving not only yield but the quality of crops is also an important aspect which, unfortunately, is often underestimated when designing new strategies to improve the stress tolerance of crop plants.…”