UV-B effects on translation in plants

MA. LORENA FALCONE FERREYRA; PAULA CASATI

La Plata

Congreso; PRIMERA REUNIÓN DE FOTOBIÓLOGOS MOLECULARES ARGENTINOS; 2011

Ultraviolet-B (UV-B) photons can cause substantial cellular damage in biomolecules, as is well established for DNA. Because RNA has the same absorption spectrum for UV as DNA, we have investigated damage to this cellular constituent. Previously, by transcriptome profiling using different light regimes, it was found that the expression of a number of ribosomal proteins is up-regulated by UV-B light in maize, among them, RPL10, an homolog of the human QM transcript. In maize leaves, UV-B radiation damages ribosomes by crosslinking ribosomal proteins to RNA. Both in maize and Arabidopsis, this is reflected by a decrease in overall translation. After 16 h without UV-B, damaged ribosomes are eliminated and translation is restored to normal levels. Neither photosynthesis nor pigment levels are affected significantly by UV-B, demonstrating that the treatment applied is not lethal and that maize leaf physiology readily recovers.Ribosomal protein L10 (RPL10) is a key factor in joining the 40S and 60S ribosomal subunits into a functional 80S ribosome; however, evidences indicate multiple extra-ribosomal functions. Arabidopsis genome contains three genes encoding RPL10 (RPL10A, RPL10B and RPL10C), while two genes were identified in the maize genome. In maize plants, UV-B exposure induces RPL10s expression, while AtRPL10s are differentially regulated by UV-B in a dosage and time dependent manner: RPL10C is induced, RPL10B is down-regulated at high UV-B intensity and RPL10A is not UV-B regulated. UV-B induces a similar reduction in the protein synthesis in A. thaliana T-DNA insertional mutants on the rpl10C and rpl10B genes; whereas in rpl10A mutant plants, the reduction in protein synthesis is more pronounced than in WT plants after the UV-B treatment, this suggests that RPL10A has an important role during translation under UV-B irradiation.