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Abstract Light triggers an enhancement of global translation during photomorphogenesis in Arabidopsis, but little is known about the underlying mechanisms. The phosphorylation of the α-subunit of eukaryotic initiation factor 2 (eIF2α) at a conserved serine residue in the N-terminus has been shown as an important mechanism for the regulation of protein synthesis in mammalian and yeast cells. However, whether the phosphorylation of this residue in plant eIF2α plays a role in regulation of translation remains elusive. Here, we show that the quadruple mutant of SUPPRESSOR OF PHYA-105 family members (SPA1-SPA4) display repressed translation efficiency after light illumination. Moreover, SPA1 directly phosphorylates the eIF2α C-terminus under light conditions. The C-term-phosphorylated eIF2α promotes translation efficiency and photomorphogenesis, whereas the C-term-unphosphorylated eIF2α results in a decreased translation efficiency. We also demonstrate that the phosphorylated eIF2α enhances ternary complex assembly by promoting its affinity to eIF2β and eIF2γ. This study reveals a unique mechanism by which light promotes translation via SPA1-mediated phosphorylation of the C-terminus of eIF2α in plants. 

The yield strength of a CrCoNiSi0.3 medium-entropy alloy is significantly increased from 450 MPa (quasi-static, 0.001 s−1) to 1600 MPa (at a strain rate of 5000 s−1) under dynamic tension, with a considerable ductility of 60%. The high strain-rate sensitivity (SRS) of strength and work hardening is obtained, and the strength SRS reaches 0.408. The dominant deformation mechanisms are abundant multiple-twinning, increasing fractions of deformation twins and phase transformation from face-centered-cubic to hexagonal-close-packed (HCP) phases with a strain rate. A universal dislocation-hardened constitutive model considering the evolution of the twin and HCP transformation is established to predict the flow stress and microstructure evolution.