Overexpression of OsMed16 Inhibits the Growth of Rice and Causes Spontaneous Cell Death.

Jie Jiang,Zhigang Wang,Zhufeng Chen,Yafeng Xin,Wei Yan,Xiaoyan Tang,Jixing Xia,Guangzhe Yang

doi:10.3390/genes12050656

Jie Jiang, Zhigang Wang + Show 6 more

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https://doi.org/10.3390/genes12050656

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Abstract

The Mediator complex transduces information from the DNA-bound transcription factors to the RNA polymerase II transcriptional machinery. Research on plant Mediator subunits has primarily been performed in Arabidopsis, while very few of them have been functionally characterized in rice. In this study, the rice Mediator subunit 16, OsMed16, was examined. OsMed16 encodes a putative protein of 1301 amino acids, which is longer than the version previously reported. It was expressed in various rice organs and localized to the nucleus. The knockout of OsMed16 resulted in rice seedling lethality. Its overexpression led to the retardation of rice growth, low yield, and spontaneous cell death in the leaf blade and sheath. RNA sequencing suggested that the overexpression of OsMed16 altered the expression of a large number of genes. Among them, the upregulation of some defense-related genes was verified. OsMed16 can regulate the expression of a wealth of genes, and alterations in its expression have a profound impact on plant growth, development, and defense responses in rice.

Highlights

Unlike prokaryotic genes, transcription of eukaryotic genes is orchestrated by RNA polymerase II (Pol II) and multiple regulatory proteins, including general transcription factors (TFs), gene-specific TFs, and Mediator [1,2]
When searching in the GenBank (National Center for Biotechnology Information, NCBI) and Rice Genome Annotation Project databases, we found that the ORF of OsMed16 was 3906 bp in length and encoded a putative protein composed of 1301 amino acid residues, which is 131 aa longer than that of OsSRF6 reported by Wathugala et al [21]
The green fluorescence signal in the control was observed in the cytoplasm, while fluorescence from OsMed16-GFP was present in the nucleus and colocalized with the OsGhd7-red fluorescent protein (RFP) protein (Figure 2b). These results indicated that OsMed16 is localized in the nucleus, which is consistent with its role as a Mediator subunit

Summary

Introduction

Transcription of eukaryotic genes is orchestrated by RNA polymerase II (Pol II) and multiple regulatory proteins, including general transcription factors (TFs), gene-specific TFs, and Mediator [1,2]. The structure of the whole Mediator complex can be divided into three main modules (head, middle, and tail) and a transiently associated kinase module, and every module has different functions in transcription [3]. The head and middle modules constitute the core Mediator and contact. Pol II and general TFs, while the tail module interacts with gene-specific TFs [3,4]. The kinase module and Pol II associate with the main modules in a mutually exclusive fashion; they act as transcriptional repressors [5,6].

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