Abstract
AP2/ERF–type transcription factors regulate important functions of plant growth and development as well as responses to environmental stimuli. A rice AP2/ERF transcription factor, OsEREBP1 is a downstream component of a signal transduction pathway in a specific interaction between rice (Oryza sativa) and its bacterial pathogen, Xoo (Xanthomonas oryzae pv. oryzae). Constitutive expression of OsEREBP1 in rice driven by maize ubiquitin promoter did not affect normal plant growth. Microarray analysis revealed that over expression of OsEREBP1 caused increased expression of lipid metabolism related genes such as lipase and chloroplastic lipoxygenase as well as several genes related to jasmonate and abscisic acid biosynthesis. PR genes, transcription regulators and Aldhs (alcohol dehydrogenases) implicated in abiotic stress and submergence tolerance were also upregulated in transgenic plants. Transgenic plants showed increase in endogenous levels of α-linolenate, several jasmonate derivatives and abscisic acid but not salicylic acid. Soluble modified GFP (SmGFP)-tagged OsEREBP1 was localized to plastid nucleoids. Comparative analysis of non-transgenic and OsEREBP1 overexpressing genotypes revealed that OsEREBP1 attenuates disease caused by Xoo and confers drought and submergence tolerance in transgenic rice. Our results suggest that constitutive expression of OsEREBP1 activates the jasmonate and abscisic acid signalling pathways thereby priming the rice plants for enhanced survival under abiotic or biotic stress conditions. OsEREBP1 is thus, a good candidate gene for engineering plants for multiple stress tolerance.
Highlights
Plants being sessile have evolved adaptive mechanisms to cope with various types of environmental stresses
Our study show that OsEREBP1 interacts with one of the eight unique Xa21-binding protein (Xb22a) in the Xanthomonas oryzae pv. oryzae (Xoo)-rice resistance pathway (S1 Fig)
OsEREBP1 belongs to a large family of AP2-domain containing transcription factors and can be classified as group VIIa class of proteins along with 13 members, which are phosphorylated by MAP kinases [4]
Summary
Plants being sessile have evolved adaptive mechanisms to cope with various types of environmental stresses. The plant specific AP2/ERF (Apetala2/ethylene responsive factor) class of transcription factors are a large family with ~163 members in rice that regulate important functions of responses to environmental stimuli or plant growth and development depending on the presence of one or two highly conserved 60 amino acid AP2 domain in the protein [4, 5] They regulate the expression of genes having a GCC box in their promoters, which include the DRE/CRT (drought responsive/C-Repeat) elements binding to CBF/DREB factors involved in abiotic stress responses. Three of the four rice genes [(OsBIERF 1–4){(Oryza sativa benzothiadiazole (BTH)-induced ethylene responsive transcriptional factors (ERF)] with a single conserved ERF domain were found to be upregulated by salt, cold, drought, wounding as well as in an incompatible interaction between rice and fungal pathogen suggesting their role in biotic and abiotic stress [10]. This study elucidates the role of OsEREBP1 transcription factor in various stress responses of rice
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