Isolation and Identification of a TaTDR-Like Wheat Gene Encoding a bHLH Domain Protein, Which Negatively Regulates Chlorophyll Biosynthesis in Arabidopsis

Yu Xia,Jingjing Du,Zheng Li,Na Niu,Yang Ren,Yulong Song,Gaisheng Zhang,Shoucai Ma,Junwei Wang,Huiyan Zhao,Zhiquan Yang,Qilu Song,Yanhong Li

doi:10.3390/ijms21020629

Abstract

Chlorophyll biosynthesis plays a vital role in chloroplast development and photosynthesis in plants. In this study, we identified an orthologue of the rice gene TDR (Oryza sativa L., Tapetum Degeneration Retardation) in wheat (Triticum aestivum L.) called TaTDR-Like (TaTDRL) by sequence comparison. TaTDRL encodes a putative 557 amino acid protein with a basic helix-loop-helix (bHLH) conserved domain at the C-terminal (295–344 aa). The TaTDRL protein localised to the nucleus and displayed transcriptional activation activity in a yeast hybrid system. TaTDRL was expressed in the leaf tissue and expression was induced by dark treatment. Here, we revealed the potential function of TaTDRL gene in wheat by utilizing transgenic Arabidopsis plants TaTDRL overexpressing (TaTDRL-OE) and TaTDRL-EAR (EAR-motif, a repression domain of only 12 amino acids). Compared with wild-type plants (WT), both TaTDRL-OE and TaTDRL-EAR were characterized by a deficiency of chlorophyll. Moreover, the expression level of the chlorophyll-related gene AtPORC (NADPH:protochlorophyllide oxidoreductase C) in TaTDRL-OE and TaTDRL-EAR was lower than that of WT. We found that TaTDRL physically interacts with wheat Phytochrome Interacting Factor 1 (PIF1) and Arabadopsis PIF1, suggesting that TaTDRL regulates light signaling during dark or light treatment. In summary, TaTDRL may respond to dark or light treatment and negatively regulate chlorophyll biosynthesis by interacting with AtPIF1 in transgenic Arabidopsis.

Highlights

Leaf photosynthesis is the basis for the formation of grain in the production of food crops
TaTDRL physically interacts with AtPIF1 and TaPIF1 in yeast two-hybrid assays. These results suggested that TaTDRL may participate in the negative regulation of chlorophyll biosynthesis by interacting with TaPIF1 in wheat
We found that TaTDRL can form heterodimers with AtPIF1 or TaPIF1, suggesting that in both Arabidopsis and wheat, these heterodimers may be involved in important developmental events, such as phytochrome signaling and chlorophyll biosynthesis

Summary

Introduction

Leaf photosynthesis is the basis for the formation of grain in the production of food crops. Phytochromes interact with a small subset of basic helix-loop-helix (bHLH) transcription factors called Phytochrome Interacting Factors (PIFs) [7,8]. These PIFs have been shown to repress seed germination, chlorophyll accumulation and the assembly of photosynthetic complexes, as well as promotion of seedling skotomorphogenesis and shade-avoidance [8,9]. PIF1 shows transcriptional activation activity in the dark, which is reduced by light-induced degradation of PIF1 to promote chlorophyll biosynthesis and seed germination in light [3]

Methods

Results

Discussion

Conclusion