CHLOROPLAST RETROGRADE SIGNALLING INVOLVED IN ALTERNATIVE SPLICING REGULATION

EZEQUIEL PETRILLO; MICAELA AMALIA GODOY HERZ; ALBERTO RODOLFO KORNBLIHTT

San Miguel de Tucumán -Tucumán - Argentina

Congreso; SAIB XLV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

With the aim of understanding the mechanisms that regulatealternative splicing in plants, we studied the Arabidopsisthalianagenes for RUBISCO ACTIVASE and the SR protein RSp31, whosealternative splicing patterns varydepending on light conditions. Inboth transcriptional units, light exposure causes an increase in theproportion of theshorter mRNA isoforms. Light intensity (not itsquality) seems to be the factor that elicits changes in splicingpatterns.Blue or red light produce similar effects as white light anddifferent photoreceptor mutant plants behave as the WT inthealternative splicing response to light. The alternative splicingpattern modulation produced by light is affected bydrugs acting onchloroplasts. The photosystem II inhibitor DCMU mimics the effectof darkness on alternative splicing.The involvement of achloroplast signal was explored by studying the splicing pattern inleaves and roots. The lighteffect observed in leaves is also seen inroots but with a time delay. Even more, if leaves and roots areseparatedprior to light treatment the effect can only be seen inleaves. This suggests that a signal produced in chloroplastscouldtrigger changes in the alternative splicing patterns of differentmRNAs acting at a systemic level. We are tryingto get moreinformation about the nature of this retrograde signal.