Nitric Oxide Regulates Seedling Growth and Mitochondrial Responses in Aged Oat Seeds

Abstract

Mitochondria are the source of reactive oxygen species (ROS) in plant cells and play a central role in the mitochondrial electron transport chain (ETC) and tricarboxylic acid cycle (TCA) cycles; however, ROS production and regulation for seed germination, seedling growth, as well as mitochondrial responses to abiotic stress, are not clear. This study was conducted to obtain basic information on seed germination, embryo mitochondrial antioxidant responses, and protein profile changes in artificial aging in oat seeds (Avena sativa L.) exposed to exogenous nitric oxide (NO) treatment. The results showed that the accumulation of H2O2 in mitochondria increased significantly in aged seeds. Artificial aging can lead to a loss of seed vigor, which was shown by a decline in seed germination and the extension of mean germination time (MGT). Seedling growth was also inhibited. Some enzymes, including catalase (CAT), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR), maintained a lower level in the ascorbate-glutathione (AsA-GSH) scavenging system. Proteomic analysis revealed that the expression of some proteins related to the TCA cycle were down-regulated and several enzymes related to mitochondrial ETC were up-regulated. With the application of 0.05 mM NO in aged oat seeds, a protective effect was observed, demonstrated by an improvement in seed vigor and increased H2O2 scavenging ability in mitochondria. There were also higher activities of CAT, GR, MDHAR, and DHAR in the AsA-GSH scavenging system, enhanced TCA cycle-related enzymes (malate dehydrogenase, succinate-CoA ligase, fumarate hydratase), and activated alternative pathways, as the cytochrome pathway was inhibited. Therefore, our results indicated that seedling growth and seed germinability could retain a certain level in aged oat seeds, predominantly depending on the lower NO regulation of the TCA cycle and AsA-GSH. Thus, it could be concluded that the application of 0.05 mM NO in aged oat seeds improved seed vigor by enhancing the mitochondrial TCA cycle and activating alternative pathways for improvement.

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

“…Delayed germination and subsequent slow growth are two major characteristics of aged seeds [9]. It has been reported that seed germination or seedling growth is suppressed in aged seeds, such as rice [32] and oat [33]. In this study, oat seed vigor was significantly reduced as the GP decreased from 100% to 70% after 48 d aging ( Figure 1A), together with decreased GI and VI ( Figure 1B), and depressed 10-days seedling growth ( Figure 1C-E).…”

Melatonin and Its Effects on Plant Systems

“…Additionally, mitochondria and chloroplast are referred to as the original site of melatonin synthesis in plants [ 28 ]. In another study, mitochondria were pinpointed as a major generation site for NO and ROS [ 150 , 151 ] and could be important in playing a key role in mitigating various stresses via NO accumulation and ROS regulation [ 151 , 152 , 153 ]. Though, the mitochondria can be damaged due to the over-production of ROS under environmental stresses [ 151 ].…”

Microarray Profiling of Circular RNA Identifies hsa_circ_0126991 as a Potential Risk Factor for Essential Hypertension

“…Lifestyle has a vital role of in the development and progression of cardiovascular diseases [Fang et al, 2010;Heron, 2015;Mao et al, 2018], and both smoking and drinking are independent risk factors for EH. Therefore, it was explored whether tobacco and alcohol consumption had an influence on the expression level of circRNAs and miRNAs.…”