CHLOROPLAST DEPENDENT ALTERNATIVE SPLICING REGULATION BY LIGHT

EZEQUIEL PETRILLO; ALBERTO RODOLFO KORNBLIHTT

Villa Carlos Paz, Córdoba, Argentina

Congreso; SAIB XLIV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008

With the aim at understanding the mechanisms that regulate alternative splicing in plants, westudied the RUBISCO Activase and the RSp31 (SR protein) genes of Arabidopsis, whose alternative splicingpatterns vary depending on light conditions. In both genes, light exposure causes an increase in the proportionof the shorter mRNA isoforms. We found that light intensity (but not quality) seems to be the factor that elicitschanges in splicing patterns. Blue or red light produce similar effects as white light and different photoreceptormutant plants behave as the WT in the alternative splicing response to white light. Drugs that inhibit the electronicphotosynthetic transport abolish the effects of light on alternative splicing. The involvement of a chloroplast signalwas explored by using chloroplast signaling mutants. Furthermore, H2O2 treatment of seedlings in the dark mimicsthe effects of light on alternative splicing, which suggests that peroxides (or ROS) might act as signal intermediates.A correlation between the proportions of splicing isoforms with gene expression suggests a transcriptional regulationof alternative splicing. Now, we are investigating whether the ROS produced by the chloroplast could be the signalthat triggers changes in transcription and alternative splicing patterns and if a possible coupling could exist betweenboth processes.