Inter-nucleosomal DNA fragmentation and loss of RNA integrity during seed ageing

Abstract

The germination of viable seeds is the basis for new plant growth and development. Seeds lose viability during storage, but the biochemical mechanisms of seed death are not fully understood. This study aimed to investigate degradation patterns of nucleic acids during seed ageing and subsequent water uptake. Seeds of Pisum sativum L. were artificially aged at 50°C and 12% seed water content (WC). Nucleic acids degradation was studied during ageing and during imbibition of four seed lots with differential viability from highly viable to dead. As seeds lost viability during ageing, DNA was gradually degraded into internucleosomal fragments, resulting in 'DNA laddering', in conjunction with disintegration of 18S and 28S rRNA bands. During imbibition, non-aged controls had high levels of DNA and RNA integrity through to radicle protrusion. In an aged seed lot with 85% total germination (TG) DNA fragmentation decreased upon imbibition probably due to nucleosome degradation, while rRNA integrity did not improve. In an aged seed lot with 44% TG, neither DNA nor rRNA integrity improved upon imbibition. Dead seeds showed DNA degradation as laddering throughout imbibition along with extensive degradation of rRNA. We present a model in which interlinked programmed and nonprogrammed events contribute to seed ageing, and suggest that protection of nucleic acids during ageing is key to seed longevity.

Transcriptome-Wide Mapping of Pea Seed Ageing Reveals a Pivotal Role for Genes Related to Oxidative Stress and Programmed Cell Death

“…In this study the transcriptional changes during the early stages of artificial ageing of garden pea ( Pisum sativum ) seeds at 50°C and 60% RH were investigated using microarrays. This follows on from previous work on nucleic acid integrity [14], redox state [4] and volatile production [15] during the later stages of ageing when seed viability starts to decline. To address the problem of nucleic acid degradation during ageing, which accompanies viability loss [14], RNA integrity was assessed in incrementally deteriorated seed lots, and microarray analyses were conducted only with RNA of satisfactory quality from viable seeds at the initial stages of ageing (up to 15 d).…”

“…Genomic DNA was extracted from approximately 50 mg freeze-dried seed powder [14]. DNA quality and quantity were assessed spectrophotometrically (Jasco, http://jasco.co.uk) at 260 nm and 280 nm.…”

Quantitative dissection of lipid degradation in rice seeds during accelerated aging

“…In rice, seed aging also leads to undesirable taste, color, and odor (List et al 1992). Age-associated physiological processes that occur during storage include genetic damage (Clarke 2003;Ogé et al 2008;Kranner et al 2011), lipid peroxidation (Sun and Leopold 1995;Bailly et al 1996), and loss of integrity in cell membranes (Hallam et al 1973). Peroxidation and hydrolysis of membrane lipids are usually recognized as essential factors in the damaging of cellular structures during seed aging.…”

Cell changes during the re-induction of desiccation tolerance in germinated seeds of Sesbania virgata (Cav.) Pers.

“…In any way, the maintenance of DNA integrity and the cell compartments of the root tissue seems to be important prerogatives to re-establish the normal seedlings development after the primary root dehydration. Alterations in DNA caused by several factors affect nucleus and ultimately the entire cell leading to compromised function of the organism (Kraner et al, 2011;Atale et al, 2014;Dresch et al, 2015).…”