BASIC LEUCINE-ZIPPER 6 (bZIP6) involved in jasmonate and ethylene signaling pathway regulates ETHYLENE RESPONSE FACTOR 1 (ERF1) gene expression in Arabidopsis
Date Issued
2015
Date
2015
Author(s)
Chu, De-Rong
Abstract
AP2/ERF proteins play crucial roles in plant growth and development and in response to environment stress. ETHYLENE RESPONSE FACTOR 1 (ERF1) transcription factor belongs to group IX in ERF family which is involved in many different hormones signaling pathways. ERF1 gene expression was synergistically activated by the jasmonate (JA) and ethylene (ET) when plant was attacked by necrotrophic pathogens to confer biotic stress tolerance. Previous study also showed that ERF1 can be induced by various abiotic stresses to confer abiotic stress tolerance. ERF1 gene expression induced by JA and ET was strongly repressed by abscisic acid (ABA) treatment implying ABA may regulate ERF1 gene expression directly or JA/ET signaling indirectly. In this study, using protoplast transactivation assay I demonstrated the biological function of ABRE (ABA-response element) cis-element in ERF1 promoter under ABA, JA and ET treatment. I found BASIC LEUCINE-ZIPPER 2 (bZIP2), bZIP6 and bZIP7 could bind to the only ABRE cis-element in the promoter of ERF1 gene using yeast one-hybrid assay. Furthermore, protoplast transactivation assay showed bZIP6 and bZIP7 could interact with ABRE cis-element but bZIP2 couldn’t. Transactivation assay revealed that bZIP6 could activate the expression of LUCIFERASE while bZIP7 could repress it, indicating bZIP6 is an activator and bZIP7 is a repressor. Moreover, bZIP6 binding to the ABRE-cis element was verified by EMSA (electrophoretic mobility shift assay) and ChIP (chromatin immunoprecipitation) assay. The bZIP6 gene expression can be induced by drought, mannitol and salt stress treatment, and also can be induced by JA or ET but not respond to ABA. In 35S::bZIP6-GFP overexpression line, ERF1 expression was greater when compare with WT plant. In conclusion, bZIP6 might be a new player involved in JA or ET signaling pathway to directly regulate ERF1 gene expression.
Subjects
abiotic stress
ABA
JA
ET
Type
thesis
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