Abstract
Experimental seed aging approaches intend to mimic seed deterioration processes to achieve a storage interval reduction. Common methods apply higher seed moisture levels and temperatures. In contrast, the “elevated partial pressure of oxygen” (EPPO) approach treats dry seed stored at ambient temperatures with high oxygen pressure. To analyse the genetic background of seed longevity and the effects of seed aging under dry conditions, the EPPO approach was applied to the progeny of the Oregon Wolfe Barley (OWB) mapping population. In comparison to a non-treated control and a control high-pressure nitrogen treatment, EPPO stored seeds showed typical symptoms of aging with a significant reduction of normal seedlings, slower germination, and less total germination. Thereby, the parent Dom (“OWB-D”), carrying dominant alleles, is more sensitive to aging in comparison to the population mean and in most cases to the parent Rec (“OWB-R”), carrying recessive alleles. Quantitative trait locus (QTL) analyses using 2832 markers revealed 65 QTLs, including two major loci for seed vigor on 2H and 7H. QTLs for EPPO tolerance were detected on 3H, 4H, and 5H. An applied controlled deterioration (CD) treatment (aged at higher moisture level and temperature) revealed a tolerance QTL on 5H, indicating that the mechanism of seed deterioration differs in part between EPPO or CD conditions.
Highlights
Knowledge of the mechanism of seed longevity has become important since international companies have started to ship seeds around the world and gene banks initiated the first seed collections at the beginning of the twentieth century
After 6 years of storage at 10% seed moisture content and −18◦C, the seed material had on average 86.2 ± 16.3%Percentage of normal seedlings (NS) and differed significantly between “Oregon Wolfe Barley (OWB)-D” (54.0%) and “OWBR” (92.5%; Supplementary Figure 2). These differences were reflected in the area under the curve (AUC) and Time to 50% germination (T50), which showed lower area and longer time to reach 50% germination for “” Dominant parent Dom (OWB-D)” (AUC = 35.8; T50 = 49.2 h) in comparison to “” Recessive parent Rec (OWB-R)” (AUC = 72.3; T50 = 27.6 h; Figure 1 and Supplementary Table 1)
To compensate for potential damage induced by high pressure and pressure release, high nitrogen pressure (EPPN) was applied to seeds of the OWB population
Summary
Knowledge of the mechanism of seed longevity has become important since international companies have started to ship seeds around the world and gene banks initiated the first seed collections at the beginning of the twentieth century. Desiccation-tolerant (orthodox) seeds extend their life span when they reach maturity, dry, and enter the glassy state (Walters et al, 2005a; Buitink and Leprince, 2008). A glass is an amorphous, solid state with high viscosity (Buitink and Leprince, 2004) where metabolic processes are reduced to a minimum or can be even excluded (Kranner et al, 2010; Fernández-Marín et al, 2013). In this state, reactive oxygen species (ROS; Bailly, 2004; El-Maarouf-Bouteau et al, 2011), non-enzymatic Amadori and Maillard reactions (Sun and Leopold, 1995), and lipid peroxidations. A temperature or RH increase cause a viscosity decrease and a glass to rubber state change with higher molecular mobility and reaction kinetics (Walters, 1998)
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