Abstract
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.
Highlights
For the conservation of plant resources, more than 7,400,000 accessions have been collected and preserved worldwide [1]
Mitochondrial morphology during the critical node of seed ageing The CN of seed ageing is described in detail in our previous studies [3, 4], in brief, it is the stage at which the seed ageing curve transforms from Phase I (P-I) to Phase II (P-II)
These results indicate that the integrity of the mitochondrial ultrastructure was seriously inhibited in rice embryos after 48 h imbibition in the CN
Summary
For the conservation of plant resources, more than 7,400,000 accessions have been collected and preserved worldwide [1]. The National Genebank of China currently holds around 395,000 accessions at -18°C; these accessions represent the base collection of commercial crops and their corresponding wild relatives including rice. Seeds continue to slowly age PLOS ONE | DOI:10.1371/journal.pone.0148013. Seed Ageing and Mitochondria Metabolism design, data collection and analysis, decision to publish, or preparation of the manuscript
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