A significant correlation between ABA-induced seed-germination delay and salt tolerance of seedling in <i>Brassica napus</i>

Under abiotic stresses, such as salt stress, abscisic acid (ABA) production is induced and enhances stress tolerance. ABA is also an important plant hormone that regulates vital biological responses, including seed gemination delay. However, the interplay between stress conditions and biological responses is not well understood. Previously, we reported a wide salt tolerance variation among Brassica napus varieties. This range of salt tolerance makes B. napus ideal for exploring the relationship between salt tolerance and ABA-induced seed germination delay. First, we investigated the ABA-induced seed-germination delay of 22 B. napus varieties, each with different salt tolerances. We observed that highly salt-tolerant varieties exhibited significant seed-germination delays when exposed to increasing ABA concentrations. Additionally, among the varieties, exogenous ABA induced a range of different germination delays, suggesting a significant correlation between germination delay and salt tolerance at the seedling stage. Expression analysis, with and without ABA treatment, for several genes involved in the ABA signalling pathway and downstream was also performed at seed germination. The results suggest the potential involvement of ABI5 and SOS1 in both germination regulation and salt tolerance.