Influence of priming-induced nuclear replication activity on storability of pepper (Capsicum annuumL.) seed

Abstract

The effect of two priming treatments in PEG solutions on nuclear replication stages of pepper (Capsicum annuumL.) embryos were evaluated using flow cytometry. Priming at −1.1 MPa for 10 d induced almost 40% of nuclei in the embryo root tips to enter the synthetic phase of nuclear division, while no DNA synthesis occurred during 6 d at−1.5 MPa and in less than 10% of the nuclei at 10 d. Both priming treatments effectively increased seed performance. A decrease of 2.7 d in mean germination time (MGT) was observed after priming in PEG solution at −1.1 MPa, while the treatment at−1.5 MPa lowered the MGT by 2.1 d. Primed and untreated seeds were subjected to controlled deterioration treatments by exposure to 45°C after equilibration at 75% RH. Both osmotic treatments considerably lowered seed tolerance to adverse storage conditions as compared with untreated seeds. However, seeds in which DNA replication was induced by priming were more sensitive to controlled deterioration than seeds in which priming did not induce nuclei to enter the synthetic phase. This could be a consequence of a higher DNA content, which is a more vulnerable target for mutation inducing factors. Alternatively the increased sensitivity could be a consequence of their more advanced progress in germinative events, making seeds less resistant to deteriorative factors imposed during storage. On the whole, from the present results it appears that the nucleic acid DNA content of the embryo only plays an additive role in influencing seed storability.