Natural Ageing-Related Alterations of Biological Markers in Maize Seeds Under Ex-Situ Conservation

Contemporary seed gene bank management emphasizes the importance of understanding seed storage behaviour to maximize the preservation of genetic material. In this context, the patterns of naturally occurring ageing-related changes in physiological and biochemical markers were evaluated by comparing the performance of freshly regenerated seed samples (control) to samples kept under cold storage (CS) for 37 years (original, CS1 samples) and five years (CS2 samples). A significant decline in seed viability and physiological quality-initial seedling development-was directly associated with the duration of cold storage, leading to a marked reduction in seedling vigour index (SVI) performance. Key biochemical markers influencing early seedling growth and vigour included total protein, the glutelins protein fraction, fructose, sucrose, both insoluble-bound and soluble-free phenolics-including phenolic acids, and β-carotene. The CS2 samples, which experienced severe water deficit during the post-zygotic phase, exhibited increased sucrose, insoluble-bound p-coumaric acid (p-CouA), insoluble-bound ferulic acid (FA), and α-tocopherol contents. Conversely, glutelins and glucose contents decreased, while genotype-specific variations were observed in albumins, globulins, fructose, maltose, insoluble-bound caffeic acid, and soluble-free p-CouA, as well as in β+γ- and δ-tocopherol contents. Given the consistent pattern of natural ageing-related changes, β-carotene, lutein+zeaxanthin, insoluble-bound FA, and particularly soluble-free FA emerge as relevant biomarkers for improved monitoring of ageing processes under ex situ conservation.