The Effects of Priming and Accelerated Ageing upon the Nucleic Acid Content of Leek Seeds and their Embryos

Abstract

Using seed priming and accelerated ageing techniques, a single lot of leek (Allium porrum) seeds was manipulated to produce four lots of seeds with different germination performance. Changes in content of the major nucleic acid species in whole seeds and embryos of two of these lots (primed and unprimed), were determined over the early stages of germination. The major effect of priming was an increased level of RNA species in the seeds and embryos, and this difference was maintained during germination. Comparison of nucleic acid levels in the dry seeds of these two lots and two others (aged and aged then primed) indicated that there was no correlation with germination performance. Similar comparisons of the nucleic acid levels in the embryos of seeds imbibed for 1 d showed only a limited correlation between rRNA levels and germination performance. Analysis of these data suggests that accelerated ageing has an adverse effect upon endosperm cells, which results in the degradation of their nucleic acids during priming. Furthermore, the viability of these aged seeds also falls during priming. The data also indicate that ratios of rRNA to DNA correlate with germination performance of the four lots of seeds studied. It is proposed that such a relationship is indicative of the efficiency of a priming treatment, and may be useful in comparisons of naturally varying seed lots.