Cloning and characterization of TaMBD6 homeologues encoding methyl-CpG-binding domain proteins in wheat.
DNA methylation is a major epigenetic marker in plants that plays a crucial role in transcriptional and developmental regulation. The DNA methylation 'code' is thought to be 'read' by a set of proteins containing methyl-CpG-binding domain (MBD). However, little is known about MBD genes in common wheat (Triticum aestivum L.). Here, we report the isolation and characterization of TaMBD6 and its homeologues (TaMBD6_A, TaMBD6_B, and TaMBD6_D) in hexaploid wheat. The cDNA was quite different among the three homeologues and InDel mutations were detected in 5'-UTR and coding region. Two types of TRs (tandem repeats) -- TR1 (57 bp) and TR2 (39 bp) -- occurred in the coding region. TaMBD6_B harbored five copies of TR1 and two copies of TR2. In contrast, TaMBD6_A lacked 30 bp between the 2nd and 3rd copy of TR1, while TaMBD6_D was missing two copies of TR1 but had three copies of TR2. TaMBD6_A, TaMBD6_B, and TaMBD6_D encoded 435, 446, and 420 amino acids, respectively. Structural analysis of TaMBD6 protein indicated that each of the three homeologues had an identical MBD domain at the N-terminal, as well as a typical nuclear localization signal. Although genomics analysis showed that two introns were included, the length of the first intron varied from 3100 bp to 3471 bp and their sequences were very different. Expression analysis demonstrated that the transcription level of TaMBD6 began to increase gradually in developing grains at 15 days after pollination while decreasing significantly in endosperm and embryo tissues during germination. Expression of TaMBD6 appeared to be positively correlated with starch metabolism in the endosperm but was negatively correlated with embryo formation and sprouting. We were also interested to learn that TaMBD6 homeologues were differentially expressed in developing wheat plants and that their expression patterns were variously affected by vernalization treatment. Further investigation revealed that TaMBD6 was induced by prolonged chilling, indicating that the protein is potentially involved in regulating the developmental transition from vegetative to reproductive stages. Although the homeologues generally showed similar differential expression patterns, TaMBD6_D and TaMBD6_B contribute more to the processes of grain development and germination while TaMBD6_A is predominant in mature plants.
Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou 450002, China; State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China; College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China.
Ruijie
R
Shi
Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou 450002, China; State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China; College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China.
Jiahui
J
Zhang
College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China.
Jingyuan
J
Li
College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China.
Ketao
K
Wang
College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China.
Haiying
H
Jia
College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China.
Lin
L
Zhang
Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou 450002, China; State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China; College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China.
Putong
P
Wang
Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou 450002, China; State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China; College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China.
Jun
J
Yin
Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou 450002, China; State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China; College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China. Electronic address: mengfanrong73@henau.edu.cn.
Fanrong
F
Meng
Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou 450002, China; State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China; College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China. Electronic address: yongchunli71@foxmail.com.
Yongchun
Y
Li
D020121:5' Untranslated Regions / Q000235:genetics; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003080:Cold Temperature; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D056625:Endosperm / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods*; D054643:INDEL Mutation; D000070593:Methyl CpG Binding Domain / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D054817:Pollination / Q000235:genetics; D011123:Polyploidy; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013213:Starch / Q000378:metabolism; D014908:Triticum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
D020121:5' Untranslated Regions; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D020033:Protein Isoforms; D013213:Starch
Developing grains; Gene expression; Homeologous genes; TaMBD6; Vernalization; Wheat