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

Huifang Yan,Peisheng Mao,Shangang Jia

doi:10.3390/ijms21051898

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.

Highlights

Seeds are the genetic materials for cultivation of almost all crop species in agriculture
Seed aging during storage is irreversible and results into the decrease or even loss of seed vigor, which in turn leads to serious agricultural problems [5]
It has been reported that seed germination or seedling growth is suppressed in aged seeds, such as rice [32] and oat [33]

Summary

Introduction

Seeds are the genetic materials for cultivation of almost all crop species in agriculture. Seed germination represents the most crucial initiation for crop development and growth, greatly relying on seed physiological quality, and influences the subsequent seedling performances in various environments [1]. As storage duration is extended, seed vigor gradually decreases and aging inevitably occurs; as a result, seeds germinate poorly and non-uniformly, and economic and genetic losses are caused [2]. The auto-oxidative reactions and resulting accumulation of reactive oxygen species (ROS) are considered as the key factors underlying seed aging, which lead to diverse deleterious metabolic alterations including disruption of cellular membranes, degradation of nucleic acid, and damage of lipids and proteins [3]. Multifarious practical strategies have been adopted to prevent or retard seed aging and vigor loss during storage, such as cryopreservation, ultra-dry storage, and free-oxygen environment [6,7,8]. It is necessary to explore seed aging and germination mechanisms, and new strategies should be developed to improve the compromised vigor and seeding value of aged seeds

Methods

Results

Conclusion