Melatonin Priming Alleviates Aging-Induced Germination Inhibition by Regulating β-oxidation, Protein Translation, and Antioxidant Metabolism in Oat (Avena sativa L.) Seeds

Abstract

Although melatonin has been reported to play an important role in regulating metabolic events under adverse stresses, its underlying mechanisms on germination in aged seeds remain unclear. This study was conducted to investigate the effect of melatonin priming (MP) on embryos of aged oat seeds in relation to germination, ultrastructural changes, antioxidant responses, and protein profiles. Proteomic analysis revealed, in total, 402 differentially expressed proteins (DEPs) in normal, aged, and aged + MP embryos. The downregulated DEPs in aged embryos were enriched in sucrose metabolism, glycolysis, β-oxidation of lipid, and protein synthesis. MP (200 μM) turned four downregulated DEPs into upregulated DEPs, among which, especially 3-ketoacyl-CoA thiolase-like protein (KATLP) involved in the β-oxidation pathway played a key role in maintaining TCA cycle stability and providing more energy for protein translation. Furthermore, it was found that MP enhanced antioxidant capacity in the ascorbate-glutathione (AsA-GSH) system, declined reactive oxygen species (ROS), and improved cell ultrastructure. These results indicated that the impaired germination and seedling growth of aged seeds could be rescued to a certain level by melatonin, predominantly depending on β-oxidation, protein translation, and antioxidant protection of AsA-GSH. This work reveals new insights into melatonin-mediated mechanisms from protein profiles that occur in embryos of oat seeds processed by both aging and priming.

Comparative Time-Course Physiological Responses and Proteomic Analysis of Melatonin Priming on Promoting Germination in Aged Oat (Avena sativa L.) Seeds

“…In conclusion, both this study and the published work proved the same outcome, that melatonin priming improved the germination of aged seeds, whether in a concentration-dependent or time-dependent manner. There were some overlapped pathways found in these two studies, such as energy metabolism (glycolysis, pyruvate metabolism and TCA cycle), protein synthesis, and amino acid metabolism (proline, serine), including DAPs such as SuSy, PK, ACO, P5CS, and SHMT [ 9 ]. However, the mechanisms involved in the time-course dependent manner of melatonin priming still differed from those identified in the process relaying on its concentrations [ 9 ].…”

“…There were some overlapped pathways found in these two studies, such as energy metabolism (glycolysis, pyruvate metabolism and TCA cycle), protein synthesis, and amino acid metabolism (proline, serine), including DAPs such as SuSy, PK, ACO, P5CS, and SHMT [ 9 ]. However, the mechanisms involved in the time-course dependent manner of melatonin priming still differed from those identified in the process relaying on its concentrations [ 9 ]. Based on the thorough analysis, three main differences were revealed.…”

“…Our previous physiological and biochemical studies focusing on oat seeds revealed that artificially aging at 45 °C led to severe damage to mitochondrial integrity [ 6 ] and lower levels of activity in the antioxidant scavenging system [ 7 ]. Moreover, proteomic analysis also uncovered that various differentially abundant proteins (DAPs) in oat seed embryos were induced by aging, mainly involved in carbohydrate and energy metabolism, protein translation, and amino acid metabolism [ 8 , 9 ]. For aged oat seeds, delayed germination and repressed post-germination growth are the two biggest impediments that restrict its broader application.…”

“…Hitherto, studies that have focused on melatonin’s role in regulating the germination of aged seeds are still very rare [ 26 ]. Our previously published results suggested that melatonin priming had great potential in alleviating aging-induced germination inhibition in oat seeds, relying on its concentration variation, by regulating β-oxidation, protein translation, and antioxidant metabolism [ 9 ]. In addition, the effects of seed priming are also time-course dependent; however, the related pathways and mechanisms of melatonin expediting the germination of aged oat seeds based on different priming durations are unknown.…”

Comparative Physiological and Proteomic Analysis Reveals Different Involvement of Proteins during Artificial Aging of Siberian Wildrye Seeds

“…This phenomenon could further result in dramatic loss in economic costs and genetic diversity [ 2 ]. Seed aging is the most common form of seed deterioration and is mainly characterized by disturbances in a variety of essential metabolic pathways and cellular biochemical processes including disruption of cellular membranes, mitochondrial dysfunction, and damage to key biological macromolecules such as proteins, lipids, nucleic acids, and carbohydrates [ 3 , 4 ]. Currently, the overproduction of reactive oxygen species (ROS; such as hydrogen peroxide (H 2 O 2 ), superoxide anion ( ) etc.)…”