Cryopreservation of sorghum seeds modifies germination and seedling growth but not field performance of adult plants

Abstract

Climate change poses risks to both wild and crop plant biodiversity, which can be mitigated by cryopreservation (usually at -196 °C in liquid nitrogen [LN]) of crop germplasm. Cryopreservation is widely regarded as a reliable method for the ex situ conservation of plant genetic resources but its effects on subsequent field performance of popular crop species such as sorghum are largely unknown. This hampers the large-scale implementation (i.e. germplasm banks) of cryostorage for such species. This short communication describes the early stages of germination and field performance of plants derived from cryopreserved sorghum seed. Compared with the control, cryopreservation significantly increased seed electrolyte leakage and from 24 to 120 hours, percentage of germination of the control was ~2.6 folds higher than cryopreserved seeds. At 0 days, chlorophyll a/b rate was ~1.7 folds higher in the control and at 7 and 14 days, chlorophyll a level (~1.5 folds) and chlorophyll a/b rate (~1.8-1.9 folds) were higher in the control. Contrastingly, at 7 days, seedlings derived from cryopreserved seeds (treatment seedlings) showed ~1.5 folds more superoxide dismutase activity and ~1.9 folds more peroxidase activity. In contrast, treatment and control adult plants were statistically comparable in terms of chlorophylls, proteins, superoxide and peroxidase activities, plant architecture, and yield components. The fact that differences in biochemical indicators observed between control and treatment seedlings did not persist in adult plants validates the use of seed cryopreservation for the conservation of sorghum genetic resources.