Characterization of transcription activation domain of EcaICE1 and its interaction with EcaSIZ1 in Eucalyptus camaldulensis

SUMOylation in plants is associated with biotic and abiotic stress responses, flowering, and other aspects of development. ICE1 protein SUMOylation by the SUMO E3 ligase SIZ1 plays important roles in plant cold tolerance. Here, we reported the subcellular localization of EcaICE1 and its interaction with EcaSIZ1 in Eucalyptus camaldulensis. The genes EcaICE1 and EcaSIZ1 were isolated by homologous cloning. The subcellular localization analysis showed that EcaICE1 was located in nucleus. Bimolecular fluorescence complementation (BiFC) analysis revealed that EcaICE1 could interact with EcaSIZ1 in the nucleus of Nicotiana benthamiana leaves. Moreover, yeast two-hybrid assay confirmed that the amino acid region from position 84 to 126 in EcaICE1 was critical for the strong transactivation activity of EcaICE1 and that the C-terminal region from position 361 to 557 in EcaICE1 was the key region for its interaction with EcaSIZ1 using different truncated lengths of non-transactivation activity of EcaICE1 as the bait protein. Collectively, our results showed that EcaICE1 may have a SUMOylation pathway similar to Arabidopsis thaliana.