Characteristics and Expression Pattern of MYC Genes in Triticum aestivum, Oryza sativa, and Brachypodium distachyon.

Shoukun Chen,Hongyan Zhao,Haifeng Li,Tengli Luo,Yue Liu,Xiaojun Nie

doi:10.3390/plants8080274

Shoukun Chen, Hongyan Zhao + Show 4 more

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https://doi.org/10.3390/plants8080274

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Abstract

Myelocytomatosis oncogenes (MYC) transcription factors (TFs) belong to basic helix-loop-helix (bHLH) TF family and have a special bHLH_MYC_N domain in the N-terminal region. Presently, there is no detailed and systematic analysis of MYC TFs in wheat, rice, and Brachypodium distachyon. In this study, 26 TaMYC, 7 OsMYC, and 7 BdMYC TFs were identified and their features were characterized. Firstly, they contain a JAZ interaction domain (JID) and a putative transcriptional activation domain (TAD) in the bHLH_MYC_N region and a BhlH region in the C-terminal region. In some cases, the bHLH region is followed by a leucine zipper region; secondly, they display tissue-specific expression patterns: wheat MYC genes are mainly expressed in leaves, rice MYC genes are highly expressed in stems, and B. distachyon MYC genes are mainly expressed in inflorescences. In addition, three types of cis-elements, including plant development/growth-related, hormone-related, and abiotic stresses-related were identified in different MYC gene promoters. In combination with the previous studies, these results indicate that MYC TFs mainly function in growth and development, as well as in response to stresses. This study laid a foundation for the further functional elucidation of MYC genes.

Highlights

BHLH family is the second largest plant transcription factor (TF) family.They are characterized by a basic helix-loop-helix (bHLH) domain, which consists of 50–60 amino acids that form two distinctive regions, the basic region and HLH region [1]
26 putative TaMYC, 7 OsMYC, and 7 BdMYC genes were identified in the relevant genomes, respectively (Figure 1), including two reported genes: TaMYC1 and OsMYC2 [15,19]
Except for TaMYC1 and OsMYC2, other 25 TaMYC genes were named as TaMYC2A to TaMYC12B

Summary

Introduction

BHLH (basic helix-loop-helix) family is the second largest plant transcription factor (TF) family. They are characterized by a bHLH domain, which consists of 50–60 amino acids that form two distinctive regions, the basic region and HLH (helix-loop-helix) region [1]. The basic region functions as a DNA-binding motif, while the HLH region forms two amphipathic α helices with a linking loop [1,2,3]. In the bHLH family, there are some special members, named myelocytomatosis oncogenes (MYC). These members are characterized by a so-called bHLH_MYC_N region in the N-terminal and a bHLH region in the C-terminal [1,2,4,5]. In Arabidopsis thaliana, MYC2 functions synergistically with MYC3 and MYC4 in regulating leaf senescence [6], root elongation [7], stamen development [8], seed production, and seed storage protein accumulation [8,9], as well as chlorophyll degradation [10]; other Arabidopsis

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