Vigna unguiculata seed priming is related to redox status of plumule, radicle and cotyledons

Abstract

Pre-germination treatments represent the physiological methods that improve plant production by modulating the metabolic activities of germination before the emergence of the radicle. It was suggested that reactive oxygen species (ROS) play a crucial role in signalling seed germination. Our work consisted in studying changes in the redox status in the embryonic axis (radicle and plumule) and in cotyledons of Vigna unguiculata (L.) Walp. non-primed, osmoprimed (30% PEG6000), hydroprimed or twice hydroprimed seeds, by estimating antioxidant activities and production of ROS. Some antioxidant enzymatic activities as well as total non-enzymatic antioxidant capacity were measured. The production of hydrogen peroxide (H2O2) and superoxide anion (O2-) was also assessed by 3,3'-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) respectively. The results obtained showed, on the one hand, that priming allows activation of antioxidant enzymes, especially in the plumule. On the other hand, these results showed that priming caused an accumulation of ROS in embryonic tissues. This may explain the improvement of seed germination performance according to the oxidative window model. Priming induced changes in the redox environment at the seed level. These changes were closely related to the pre-germination treatments. Indeed, a double cycle of hydration-rehydration induced the broadest spectrum of modifications of the redox status, which would explain the improvement of the seed vigour.