Abstract
Transcriptional regulation is involved in responding to cadmium (Cd) stress in plants. However, the molecular mechanisms of Cd stress responses regulated by transcription factors remain largely unknown in plants. In this study, a rice (Oryza sativa) NAC (no apical meristem [NAM]; Arabidopsis transcription activation factor [ATAF]; cup-shaped cotyledon [CUC]-related) family transcription factor, OsNAC300, was isolated and functionally characterized for its involvement in Cd stress responses and tolerance. OsNAC300 was localized to the nucleus. OsNAC300 was mainly expressed in roots and significantly induced by Cd treatment. Knockout of OsNAC300 resulted in increased sensitivity to Cd stress, while its overexpression lines enhanced tolerance to Cd stress. RNA-Seq analysis revealed that the mutant is impaired in regulating some important genes that were responsive to Cd stress in wild-type rice, such as the pathogenesis-related genes 10a (OsPR10a), OsPR10b, chalcone synthase 1 (OsCHS1), and several others, which was validated by reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis. Moreover, chromatin immunoprecipitation-qPCR assays and luciferase reporter assays demonstrated that OsNAC300 directly binds to the promoters of OsPR10a, OsPR10b, and OsCHS1 and activates their transcription. Overall, OsNAC300 is an important regulatory factor in Cd stress responses and tolerance in rice.
Highlights
Cadmium (Cd) is a highly toxic metal element to almost all organisms, including humans and plants [1,2]
Using the ProtComp 9.0 program, we predicted that OsNAC300 is a nuclear protein with nuclear localization signal peptide (NLS)
“Defense-related protein” was the most enriched biological process in the 58 genes, including OsCHS1, OsPR10a, and OsPR10b. These genes have been proposed to be involved in environmental stresses [14] and were deregulated in osnac300-1 mutants. These results indicated that OsNAC300 is either directly or indirectly involved in the activation of genes induced by Cd stress, including OsPR10a, OsPR10b, and OsCHS1
Summary
Cadmium (Cd) is a highly toxic metal element to almost all organisms, including humans and plants [1,2]. The expression of CHS has been induced in various plant species under different forms of stress, such as UV, wounding, herbivory, and microbial infections (reviewed in Dao et al [11]). These findings implied the potential role of flavonoids as antioxidants to remove ROS generated under Cd stress in plants
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