BrLETM2 Protein Modulates Anthocyanin Accumulation by Promoting ROS Production in Turnip (Brassica rapa subsp. rapa)

In ‘Tsuda’ turnip, the swollen root peel accumulates anthocyanin pigments in a light-dependent manner, but the mechanism is unclear. Here, mutant g120w which accumulated extremely low levels of anthocyanin after light exposure was identified. Segregation analysis showed that the anthocyanin-deficient phenotype was controlled by a single recessive gene. By using bulked-segregant analysis sequencing and CAPS marker-based genetic mapping analyses, a 21.6-kb region on chromosome A07 was mapped, in which a calcium-binding EF hand family protein named BrLETM2 was identified as the causal gene. RNA sequencing analysis showed that differentially expressed genes (DEGs) between wild type and g120w in light-exposed swollen root peels were enriched in anthocyanin biosynthetic process and reactive oxygen species (ROS) biosynthetic process GO term. Furthermore, nitroblue tetrazolium (NBT) staining showed that the ROS level decreased in g120w mutant. Anthocyanins induced by UV-A were abolished by the pre-treatment of seedlings with DPI (an inhibitor of nicotinamide adenine nucleoside phosphorylase (NADPH) oxidase) and decreased in g120w mutant. These results indicate that BrLETM2 modulates ROS signaling to promote anthocyanin accumulation in turnip under UV-A and provides new insight into the mechanism of how ROS and light regulate anthocyanin production.     

Effective Optimization-Simulation Model for Flood Control of Cascade Barrage Network

In this study, a novel simulation-optimization model for the optimal flood control of the cascade barrage network was proposed by combining a simulation-based optimization method with a one-dimensional flood numerical analysis method. The simulation-based optimization method determines the optimal operation rules of cascade barrages, including the pre-discharge stage algorithm and the main-discharge stage algorithm for the securement of flood control storage and the establishment of a minimal discharge plan. The optimal operation rules describe the detailed operation process of barrage floodgates including full and partial opening and provide the upper and downstream boundary conditions for the flood numerical analysis method, which evaluate the flood propagation in the river channel between barrages. The proposed model was applied to the flood control of the six-cascade barrage network in the Taedong River, Democratic People’s Republic of Korea, and its effectiveness was verified in comparison with a well-known PSO-optimization method. The results show that the proposed model is superior to the existing other method and practically applicable to the flood control in the rivers with cascade barrage network.