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- Title
A Membrane-Bound NAC-Like Transcription Factor OsNTL5 Represses the Flowering in Oryza sativa.
- Authors
Guo, Siyi; Dai, Shaojun; Singh, Prashant K.; Wang, Hongyan; Wang, Yanan; Tan, Jeanie L. H.; Wee, Wanyi; Ito, Toshiro
- Abstract
In spite of short-day (SD) nature, rice (Oryza sativa) shares a conserved photoperiodic network for flowering control with long-day plants like Arabidopsis thaliana. Flowering or heading is an important agronomic trait in rice. NAC transcription factors (TFs) are well-conserved and one of the largest families of plant TFs. However, their function in flowering or heading time is not well-known yet. A preferential expression of a membrane-bound NAC-like TF OsNTL5 in developing leaves and panicles of rice indicated to us its putative role in flowering. To examine its function, three independent constructs was generated, one with a deletion in the C terminus membrane-spanning domain (OsNTL5ΔC), OsNTL5ΔC fused with the SRDX transcriptional repressor motif and OsNTL5ΔC used with the VP16 activation domain under the Ubiquitin promoter to produce the overexpressing lines OsNTL5ΔC, OsNTL5ΔC-SRDX, and OsNTL5ΔCVP, respectively in rice. The OsNTL5ΔC-VP line showed an early-flowering phenotype. In contrast to this, the plants with OsNTL5ΔC and OsNTL5ΔC-SRDX showed a very strong late-flowering phenotype, suggesting that OsNTL5 suppresses flowering as a transcriptional repressor. The protein subcellular localization assay suggested that N-terminal part of the OsNTL5 is localized to the nucleus after the protein is cleaved from its membrane-spanning domain at the C-terminal end and functions as a TF. Expression of flowering genes responsible for day length signals such as Early Heading Date 1 (Ehd1), Heading Date 3a (Hd3a), and Rice Flowering Locus T1 (RFT1) was significantly changed in the overexpression lines of OsNTL5ΔC-VP, OsNTL5ΔC, and OsNTL5ΔCSRDX as analyzed by Quantitative Real-time PCR. ChIP-qPCR and rice protoplasts assays indicate that OsNTL5 directly binds to the promoter of Ehd1 and negatively regulates the expression of Ehd1, which shows antagonistic photoperiodic expression patterns of OsNTL5 in a 24-h SD cycle. Hence in conclusion, the NAC-like TF OsNTL5 functions as a transcriptional repressor to suppress flowering in rice as an upstream factor of Ehd1.
- Subjects
TRANSCRIPTION factors; RICE; FLOWERING of plants
- Publication
Frontiers in Plant Science, 2018, p1
- ISSN
1664-462X
- Publication type
Article
- DOI
10.3389/fpls.2018.00555