LIGHT REGULATION OF ALTERNATIVELY SPLICED GENES DURING Arabidopsis thaliana SEED GERMINATION

TOGNACCA, ROCÍO; SERVI, LUCAS; BOTTO, JAVIER; PETRILLO, EZEQUIEL

Congreso; LIV Reunión Anual SAIB; 2018

Light is one of the most important factors regulating seed germination, plant growth and development. Light-sensing photoreceptors tightlyregulate gene expression to control photomorphogenic responses. Although many levels of gene expression are modulated by photoreceptors, itis still unknown the importance of alternative splicing (AS) in the promotion of seed germination by light. During the last years consecutivereports demonstrated a steadily increasing percentage of alternatively spliced genes in plants. AS can lead to different outcomes and can producetranscripts that code for proteins with altered or lost function. Several examples have demonstrated AS functional importance in variousprocesses like photosynthesis, defense responses, the circadian clock, hormone signaling, flowering time and metabolism. The aim of this workis to study the transcriptome and alternatively spliced genes expressed during light induction of seed germination in Arabidopsis thaliana. Weevaluated the effect of R/FR (red/far red) light on AS in light-induced Col-0 seeds using high-throughput RNA sequencing (RNA-seq). Wefound that a Rp (red pulse) compared to a FRp (far red pulse) given after cold stratification, affects the AS of 226 genes. Some of these ASevents were associated with genes involved in mRNA processing, RNA splicing and mRNA metabolic processes. Moreover, we showed thatsome of these AS events are highly conserved across distinct developmental stages in plants. By using a combination of R/FR light andphytochrome mutants approach, we showed that light modulates the AS pattern of some of these genes, i.e.: U2AF65 (an auxiliary splicingfactor) in a phytochrome B exclusive manner and RS31 (a splicing regulator), in a phytochrome independent manner. Our results demonstratethat in Arabidopsis seeds (1) R/FR light triggers AS changes in different genes and, in some cases, (2) light exerts its effects through the actionof phytochrome B. We conclude that AS is a source of gene expression diversity for proteins involved in the promotion of seed germination bylight