Abstract
Background: Plants are continuously challenged by different environment stresses, and they vary widely in their adjustability. NAC (NAM, ATAF and CUC) transcription factors are known to be crucial in plants tolerance response to abiotic stresses, such as drought and salinity. ANAC019, ANAC055, and ANAC072, belong to the stress-NAC TFs, confer the Arabidopsis abiotic stress tolerance. Results: Here we isolated two stress-responsive NACs, CiNAC3 and CiNAC4, from Caragana intermedia, which were induced by ABA and various abiotic stresses. Localization assays revealed that CiNAC3 and CiNAC4 localized in the nuclei, consistent with their roles as transcription factors. Histochemistry assay using Pro(CiNAC4)::GUS transgenic Arabidopsis showed that the expression of the GUS reporter was observed in many tissues of the transgenic plants, especially in the root vascular system. Overexpression of CiNAC3 and CiNAC4 reduced ABA sensitivity during seed germination, and enhanced salt tolerance of the transgenic Arabidopsis. Conclusions: We characterised CiNAC3 and CiNAC4 and found that they were induced by numerous abiotic stresses and ABA. GUS histochemical assay of CiNAC4 promoter suggested that root, flower and local damaged tissues were the strongest stained tissues. Overexpression assay revealed that CiNAC4 play essential roles not only in promoting lateral roots formation, but also in responding to salinity and ABA treatment of Arabidopsis.