Variability in light-, gibberellin- and nitrate requirement of Arabidopsis thaliana seeds due to harvest time and conditions of dry storage

Abstract

Listen

Translate article

Freshly harvested seeds of Arabidopsis thaliana harvested in different seasons showed considerable variability in requirement for light (wild type), gibberellins (GAs) (wild type, GA deficient, ga1-2 mutant) and nitrate. Generally, sensitivity to light was high in seed lots harvested between September and March and significantly lower in those harvested between April and June. Sensitivity to GAs varied in a nearly parallel way. These differences in sensitivity can be attributed to conditions during seed development, like temperature and nitrate availability. Endogenous nitrate levels varied enormously amongst seed lots (about a factor 600) and were weakly correlated to the germination capacity at 10°C after 15 min of red light irradiation. In addition, differences in sensitivity to nitrate may be responsible for the enormous differences in light requirement between seed lots. Other unknown factors may contribute as well. At a germination temperature of 10°C seeds were much more sensitive to GAs and light than at 24°C. The degree of dormancy rapidly declined upon dry storage of the seeds. Loss of dormancy was accelerated with increasing storage temperature; the requirements for light and GAs became less strict. Sensitivity to GAs increased and seeds that initially only responded to continuous irradiation with white fluorescent light, responded to a single red light pulse after 15 months of dry storage at 2°C. It is demonstrated that studies on germination and dormancy of A. thaliana are hampered by the large variability of seed material and the relatively high rate of after-ripening.