DECIPHERING THE NATURE OF A RETROGRADE SIGNAL THAT REGULATESALTERNATIVE SPLICING IN ARABIDOPSIS

PETRILLO, EZEQUIEL; GODOY HERZ, MICAELA; KORNBLIHTT, ALBERTO

Congreso; Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2010

With the aim of understanding alternative splicing regulation in plants we analyzed about 100 alternative splicing events with a high-resolution RT-PCR panel and found that 40% of them respond to light/dark transitions. We chose the mRNA of the SR protein Rsp31 as a model to investigate the mechanisms involved. Light exposure, perceived by the chloroplast, increases the proportion of the functional mRNA splicing isoform of RSp31. The effect is only observed in roots that have not been dissected from shoots before light exposure, suggesting that the signal is able to travel from leaves to roots. Chloroplast signals include reactive oxygen species (ROS), sugars, the redox-state of the electronic transport chain, plastid gene expression and chlorophyll metabolism. Mutants of the chlorophyll biosynthesis pathway behave as wild type plants, ruling out the involvement of this pathway. Both H2O2 and sucrose mimic the effects of light on Rsp31 alternative splicing. However, flavodoxin-overexpressants do not inhibit the effect of light, and methylviologen treated plants behave as control plants, which favors a role for sugar signaling but does not completely rule out ROS. To get deeper insights into the nature of the signaling we are currently using Arabidopsis mutants and drugs that affect the redox-state of the plastoquinone pool.