Multilevel effects of light on ribosome dynamics in chloroplasts program genome-wide and psbA-specific changes in translation.

摘要: Plants and algae adapt to fluctuating light conditions optimize photosynthesis, minimize photodamage, prioritize energy investments. Changes in the translation of chloroplast mRNAs are known contribute these adaptations, but scope magnitude responses unclear. To clarify phenomenology, we used ribosome profiling analyze maize seedlings following dark-to-light light-to-dark shifts. The results resolved several layers regulation. (i) psbA mRNA exhibits a dramatic gain ribosomes within minutes after shifting plants reverts low occupancy one hour dark, correlating with need replace damaged PsbA Photosystem II. (ii) Ribosome on all other remains similar that at midday even 12 hours dark. (iii) Analysis dynamics presence lincomycin revealed global decrease elongation rate shortly pausing specific sites changed very little during light-shift regimes. A less comprehensive analysis Arabidopsis gave excepting trend toward reduced end night. Our show except maintain short-term shifts, nonetheless translated higher rates due plastome-wide increase rate. light-induced recruitment is superimposed this response, producing rapid massive synthesis. These findings highlight unique translational response mature chloroplasts, which steps light-regulated context II repair, provide foundation explore mechanisms underlying psbA-specific effects translation.