Contribution of LIMYB in arabidopsis thaliana UV-B response

Abstract

LIMYB is a transcription factor involved in Arabidopsis thaliana plant defense against viral infection. In this signaling pathway, LIMYB interacts with the ribosomal protein RPL10A in nuclei to downregulate translational machinery. Thus, A. thaliana plants overexpressing LIMYB show lower protein synthesis, less association of viral mRNA with polisomes and higher tolerance to viral infection. Although LIMYB expression is not regulated by UV-B radiation, our aim is to elucidate whether LIMYB, in cooperation or not with RPL10A, is involved in UV-B response. For this purpose, we investigated the effect of UV-B in Arabidopsis limyb mutants and overexpressing plants. First, we analyzed transcript levels of previously described LIMYB target genes such as RPL4, RPL13, RPS25, RPL28e and RPS13a after UV-B exposure. Both the mutation and the overexpression of LIMYB mainly does not affect the regulation of gene expression by UV-B radiation. However, LIMYB-overexpressing lines show less inhibition of primary root elongation after UV-B treatment with respect to WT plants, while the opposite is observed in limyb mutants. In addition, LIMYB-overexpressing plants exhibit decreased membrane damage, not change in the chlorophyll content and increased levels of UV-absorbing phenolic compounds after UV-B exposure in comparison to WT and mutant plants. Our results suggest that LIMYB might participate in UV-B response and its overexpression could improve UV-B tolerance in Arabidopsis.