FUNCTIONAL CHARACTERIZATION OF AN ERF TRANSCRIPTION FACTOR WHICH MODULATES ABA SENSITIVITY AND JA-RELATED RESPONSES IN ARABIDOPSIS

VALLE, EM; OSELLA, AV; MENGARELLI, DIEGO; ZANOR, MI

Salta

Congreso; LV Annual SAIB Meeting and XIV PABMB conference; 2019

SAIB

Stress signal transduction pathways are still a matter of debate. In Arabidopsis, several members of the APETALA2/ETHYLENE RESPONSE FACTOR transcription factor (TF) superfamily were found to be involved in plant development and environmental stress responses. Here, we report the function analysis of an uncharacterized member of this family in Arabidopsis that we called ERF-SR (for ERF-stress related). This TF belongs to the ERF subfamily and possess only one AP2 domain and does not have any additional conserved motif. We have found it as superoxide specific induced gene and lines with altered levels of ERF-SR showed differential accumulation of ROS. Constitutive overexpression (ox) lines accumulate lower levels of ROS and in contrast, artificial micro RNA-(ami) lines show increased ROS levels in leaves when compared to wild type plants. Other contrasting phenotypes were related to ABA responses. Ox lines were hypersensitive to ABA in seed germination and root growth assays and also were hypersensitive to osmotic stress conditions, (both in the presence of high salt and PEG). On the contrary, ami lines showed enhanced tolerance to salt stress during early stages of growth. To dissect the altered stress related processes observed in these lines, proteomic analysis of the lines grown in the presence of 0.5 uM ABA was performed. The results revealed mainly changes in metabolic processes, photosynthesis, redox processes, responses to stress and responses to hormones. Changes in processes like glutamate and chlorophyll metabolism are in agreement with the observation that chlorophyll content of ami lines are higher compared to wild type and ox lines levels of plants grown in the presence of ABA. Additionally, several proteins related to jasmonic acid (JA) were found differentially accumulated in ami lines, such as VSP1 and JR1. By analysis of transcripts levels of genes involved in JA responses by qPCR of plants with altered levels of this TF we confirmed this observation. Transcripts of ERF1 and ORA59 which are an upstream component of JA-signaling as well as the JA-marker PDF1.2 were found significantly induced in ami lines reinforcing the idea that JA processes are altered in these lines. There is increasing evidence that ABA and other hormonal signalling pathways are interwoven with each other into an intricate network to regulate plant responses to osmotic and salt stresses. Altogether, these data suggest that ERF-SR regulates the expression of genes involved in ABA- and JA- signal transduction pathways