The Arabidopsis thaliana ecotype Ct-1 achieves higher salt tolerance relative to Col-0 via higher tissue retention of K+ and NO3-

Abstract

Agriculture is vital for global food security, and irrigation is essential for improving crop yields. However, irrigation can pose challenges such as mineral scarcity and salt accumulation in the soil, which negatively impact plant growth and crop productivity. While numerous studies have focused on enhancing plant tolerance to high salinity, research targeting various ecotypes of Arabidopsis thaliana has been relatively limited. In this study, we aimed to identify salt-tolerant ecotypes among the diverse wild types of Arabidopsis thaliana and elucidate their characteristics at the molecular level. As a result, we found that Catania-1 (Ct-1), one of the ecotypes of Arabidopsis, exhibits greater salt tolerance compared to Col-0. Specifically, Ct-1 exhibited less damage from reactive oxygen species (ROS) than Col-0, despite not accumulating antioxidants like anthocyanins. Additionally, Ct-1 accumulated more potassium ions (K⁺) in its shoots and roots than Col-0 under high salinity, which is crucial for water balance and preventing dehydration. In contrast, Ct-1 plants were observed to accumulate slightly lower levels of Na⁺ than Col-0 in both root and shoot tissues, regardless of salt treatment. These findings suggest that Ct-1 plants achieve high salinity resistance not by extruding more Na⁺ than Col-0, but rather by absorbing more K⁺ or releasing less K⁺. Ct-1 exhibited higher nitrate (NO₃^-) levels than Col-0 under high salinity conditions, which is associated with enhanced retention of K⁺ ions. Additionally, genes involved in NO₃^- transport and uptake, such as NRT1.5 and NPF2.3, showed higher transcript levels in Ct-1 compared to Col-0 when exposed to high salinity. However, Ct-1 did not demonstrate significantly greater resistance to osmotic stress compared to Col-0. These findings suggest that enhancing plant tolerance to salt stress could involve targeting the cellular processes responsible for regulating the transport of NO₃^- and K⁺. Overall, our study sheds light on the mechanisms of plant salinity tolerance, emphasizing the importance of K⁺ and NO₃^- transport in crop improvement and food security in regions facing salinity stress.