Carbonylated proteins accumulated as vitality decreases during long-term storage of beech (Fagus sylvatica L.) seeds

Abstract

Key message Carbonylation of proteins associated with a stress response may contribute to the lowered viability of naturally aged beech seeds, especially the desiccation tolerance-associated proteins and USP-like protein.Abstract Proteins are modified by a large number of reactions that involve reactive oxygen species-mediated oxidation. The direct oxidation of amino acids produces 2,4-dinitrophenylhydrazine-detectable protein products. Carbonylation is irreversible, and carbonylated proteins are marked for proteolysis or can escape degradation and form high molecular weight aggregates, which accumulate with age. Beech (Fagus sylvatica L.) seeds stored under optimal conditions for different periods of time, ranging from 2 to 13 years, were analyzed. Protein carbonylation was examined as a potential cause for the loss of viability of beech seeds, and the characteristic spots of protein carbonyls were identified. Here, we present and discuss the role of carbonylation in the proteome of beech seeds that contribute to the loss of seed viability during natural aging. The long-term storage of beech seeds is intricate because their germination capacity decreases with age and is negatively correlated with the level of protein carbonyls that accumulate in the seeds. We establish that protein synthesis, folding and degradation are the most affected biochemical traits in long-term stored beech seeds. In addition, we suggest that proteins associated with the stress response may have contributed to the lowered viability of beech seeds, especially the desiccation toleranceassociated proteins that include T-complex protein 1 and the universal stress protein (USP)-like protein, which is identified as carbonylated for first time here.

Multiple Subcellular Localizations of Dehydrin-like Proteins in the Embryonic Axes of Common Beech (Fagus sylvatica L.) Seeds During Maturation and Dry Storage

“…Dry embryonic axes of beech seeds contained no more than 10 % water and thus consist of desiccated tissue. Recently, it was shown that dehydrins play a role in desiccation tolerance (Wang and others 2012), and this function is conserved in stored beech seeds (Kalemba and Pukacka 2014). Dehydrins associated with amyloplasts may act by rescuing enzyme functions in key metabolic processes during dehydration.…”

“…During development, beech seeds become desiccation tolerant beginning at the 16th week after flowering (WAF) (Kalemba and others 2009) like all other orthodox type seeds (Roberts 1973). Beech seeds were finally classified into the intermediate category (León-Lobos and Ellis 2002) due to their reduced longevity during storage (León-Lobos and Ellis 2002;Pukacka and Ratajczak 2007;Kalemba and Pukacka 2014); the seeds cannot survive dehydration below those in equilibrium with approximately 40-50 % relative humidity (Ellis and others 1990).…”

Age-related changes in protein metabolism of beech (Fagus sylvatica L.) seeds during alleviation of dormancy and in the early stage of germination

“…The germination capacity of beech seeds stored in optimal conditions for up to 10 years was strongly positively correlated with soluble protein level, whereas a strong negative correlation was found between germination capacity and hydrogen peroxide, superoxide anion radical and lipid hydroperoxide (LHPO) levels (Pukacka and Ratajczak, 2007). A clear negative correlation was demonstrated between the protein carbonylation level and the germination capacity of beech seeds stored long-term (Kalemba and Pukacka, 2014). Ratajczak et al (2015) established that the loss of beech seed germinability is related to ROS accumulation in the root apical meristem, and DNA fragmentation occurred primarily in embryonic axes of seeds stored for 5 years or longer.…”

“…ROS prompt many oxidative injuries to macromolecular components of cells (ElMaarouf-Bouteau et al, 2011;Kranner et al, 2011), of which the most affected are proteins (Davies, 2005). Protein oxidation (i.e., carbonylation) can affect the activities of enzymes and increase the susceptibility of proteins to proteolysis (Rajjou et al, 2012;Kalemba and Pukacka, 2014). The loss of seed vigour induced by ageing is thus the result of protein changes in dry seeds during storage, the regulation of protein synthesis and turnover, and posttranslational modifications (PTMs), as well as a reduction in translational activity during germination (Rajjou et al, 2012).…”

“Nitrosative Door” in Seed Dormancy Alleviation and Germination

“…This modification is commonly known as a marker of oxidative metabolic disorder and in seeds it was linked mostly to process of aging and loss of viability (Terskikh et al 2008;Kalemba and Pukacka 2014) characterized by over accumulation of ROS. However, carbonylation of some proteins (e.g., proteins or peptides that serve as reserved material) is a positive process required for termination of seed germination (Job et al 2005).…”