Comprehensive Mitochondrial Metabolic Shift during the Critical Node of Seed Ageing in Rice

• Published in: PloS one 2016-04, Vol.11 (4), p.e0148013-e0148013
• Main Authors: Yin, Guangkun, Whelan, James, Wu, Shuhua, Zhou, Jing, Chen, Baoyin, Chen, Xiaoling, Zhang, Jinmei, He, Juanjuan, Xin, Xia, Lu, Xinxiong
• Format: Article
• Language: English
• Subjects: Adenosine triphosphatase; Adenosine Triphosphatases - metabolism; Adenosine triphosphate; Aging; Aging (Biology); Aging - metabolism; Apoptosis; Arabidopsis; ATP; ATP synthase; Biology and Life Sciences; Biosynthesis; Carbon - metabolism; Citric Acid Cycle - physiology; Crop science; Cytochrome; Cytochrome c; Cytochromes c - metabolism; Damage accumulation; Down-Regulation - physiology; Electron transport; Electron transport chain; Electron Transport Complex IV - metabolism; Enzymes; Gene expression; Intermediates; Malate; Malate dehydrogenase; Malate Dehydrogenase - metabolism; Metabolism; Mitochondria; Mitochondria - metabolism; Mitochondrial Proteins - metabolism; Nitrogen - metabolism; Oryza - metabolism; Oryza sativa; Oxidase; Oxidation-Reduction; Oxidative stress; Oxidative Stress - physiology; Oxygen; Oxygen consumption; Oxygen Consumption - physiology; Pennisetum glaucum; Phase transitions; Physiological aspects; Plant metabolism; Plant mitochondria; Proteins; Reactive oxygen species; Reactive Oxygen Species - metabolism; Regulatory mechanisms (biology); Research and Analysis Methods; Rice; Seeds; Seeds - metabolism; Studies; Transcription; Transformation; Tricarboxylic acid cycle; Ultrastructure
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0148013

The critical node (CN) in seed aging in rice (Oryza sativa) is the transformation from Phase I (P-I) to Phase II (P-II) of the reverse S-shaped curve (RS-SC). Although mitochondrial dysfunction plays a key role in seed ageing, the metabolic shift in the CN remains poorly understood. Here, we investigated the mitochondrial regulatory mechanisms during the CN of rice seed ageing. We showed that during the CN of seed ageing, the mitochondrial ultrastructure was impaired, causing oxygen consumption to decrease, along with cytochrome c (cyt c) oxidase and malate dehydrogenase (MDH) activity. In addition, the transcript levels for the alternative pathway of the electron transport chain (ETC) were significantly induced, whereas the transcripts of the cytochrome oxidase (COX) pathway were inhibited. These changes were concomitant with the down-regulation of mitochondrial protein levels related to carbon and nitrogen metabolism, ATP synthase (ATPase) complex, tricarboxylic acid cycle (TCA) cycle, mitochondrial oxidative enzymes, and a variety of other proteins. Therefore, while these responses inhibit the production of ATP and its intermediates, signals from mitochondria (such as the decrease of cyt c and accumulation of reactive oxygen species (ROS)) may also induce oxidative damage. These events provide considerable information about the mitochondrial metabolic shifts involved in the progression of seed ageing in the CN.