Transcriptome-wide mapping of pea seed ageing reveals a pivotal role for genes related to oxidative stress and programmed cell death.

Hongying Chen,Louise Colville,Daniel Osuna,Oscar Lorenzo,Gerhard Leubner-Metzger,Ilse Kranner,Helge Küster,Kai Graeber,Ken Mills

doi:10.1371/journal.pone.0078471

Abstract

Understanding of seed ageing, which leads to viability loss during storage, is vital for ex situ plant conservation and agriculture alike. Yet the potential for regulation at the transcriptional level has not been fully investigated. Here, we studied the relationship between seed viability, gene expression and glutathione redox status during artificial ageing of pea (Pisum sativum) seeds. Transcriptome-wide analysis using microarrays was complemented with qRT-PCR analysis of selected genes and a multilevel analysis of the antioxidant glutathione. Partial degradation of DNA and RNA occurred from the onset of artificial ageing at 60% RH and 50°C, and transcriptome profiling showed that the expression of genes associated with programmed cell death, oxidative stress and protein ubiquitination were altered prior to any sign of viability loss. After 25 days of ageing viability started to decline in conjunction with progressively oxidising cellular conditions, as indicated by a shift of the glutathione redox state towards more positive values (>−190 mV). The unravelling of the molecular basis of seed ageing revealed that transcriptome reprogramming is a key component of the ageing process, which influences the progression of programmed cell death and decline in antioxidant capacity that ultimately lead to seed viability loss.

Highlights

IntroductionThe majority of seeds are orthodox (desiccation tolerant), and undergo dehydration during maturation prior to shedding
The majority of seeds are orthodox, and undergo dehydration during maturation prior to shedding
Nucleic acid oxidation occurs in seeds with moisture content (MC) as low as 4%, and RNA is more prone to oxidation than DNA in part due to its single stranded structure. mRNA was found to be more sensitive to oxidation than total RNA, and oxidation was a targeted process, which would provide a means of modulating cell signaling during the early stages of imbibition [11,12]

Summary

Introduction

The majority of seeds are orthodox (desiccation tolerant), and undergo dehydration during maturation prior to shedding. Even in the dry state ROS formation as a result of auto-oxidative reactions leads to a gradual accumulation of oxidative damage to proteins, lipids and nucleic acids, and this eventually leads to viability loss [1,2,3,4]. Studies of dormancy alleviation during dry after-ripening showed that whilst some transcripts increased in abundance, most declined [11]. This may reflect chemical reactions that are occurring in the dry seed rather than changes in gene expression. MRNA was found to be more sensitive to oxidation than total RNA, and oxidation was a targeted process, which would provide a means of modulating cell signaling during the early stages of imbibition [11,12] Nucleic acid oxidation occurs in seeds with moisture content (MC) as low as 4%, and RNA is more prone to oxidation than DNA in part due to its single stranded structure. mRNA was found to be more sensitive to oxidation than total RNA, and oxidation was a targeted process, which would provide a means of modulating cell signaling during the early stages of imbibition [11,12]

Methods

Results

Conclusion