Peroxidases in Relation to Removal of Dormancy and Germination of Apple Embryos

Abstract

The changes in germination, peroxidase activity and isoperoxidase spectrum have been studied in apple embryos at 5°C (stratification) and at 20° C in the presence or absence of seed coats. The embryo dormancy is progressively released at 5°C, but not at 20°C. The peroxidase activity in embryos covered with seed coats is very low at 5°C as well as at 20°C which corresponds to a restricted number of isoenzymes. In isolated embryos the peroxidase activity increases significantly. This is due to an increase in both the number and the activity of the isoperoxidases and it is more pronounced at 20° C than at 5°C.The obtained results suggest that the soluble peroxidases are not involved in the process of the release of embryo dormancy. The variations observed are attributed to the growth process following germination, which can occur even at low temperature.

Metabolic control of embryonic dormancy in apple seed: seven decades of research

“…The total peroxidase activity does not change during incubation of intact seeds, independently of the temperature. In cultured isolated embryos, the activity increases sharply, but the increase is better pronounced at 20°C than at 5°C (Thévenot et al 1977). This observation suggests that peroxidases in apple seeds are not involved in the processes of dormancy removal, but rather in the growth following germination.…”

Hormones in Seed Dormancy and Germination

“…Among changes observed under conditions of cold stratification only few occur during warm stratification. There are: increase of peroxidase activity (Thevenot et al, 1977), decrease in ABA level (Balboa-Zavala and Dennis, 1977), maximum content of free HCN (Dziewanowska et at.. 1979b). The pattern of other changes under conditions of warm stratification is quite different (e. g., the involvement of pentose phosphate pathway, Bogatek and Lewak, 1978); some others, are not observed at all.…”