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The Mediator subunit OsMED15a is a transcriptional co-regulator of seed size/weight-modulating genes in rice

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Title The Mediator subunit OsMED15a is a transcriptional co-regulator of seed size/weight-modulating genes in rice
 
Creator Dwivedi, Nidhi
Maji, Sourobh
Waseem, Mohd
Thakur, Pallabi
Kumar, Vinay
Parida, Swarup K.
Thakur, Jitendra K.
 
Subject Crop improvement
Gene regulation
Grain size
MED15
Mediator
Plant growth
QTL mapping
Rice (Oryza sativa)
Seed development
Transcription
 
Description Accepted date: 2 September 2019
Although several transcription factors (TFs) that regulate seed size/weight in plants are known, the molecular landscape regulating this important trait is unclear. Here, we report that a Mediator subunit, OsMED15a, links rice grain size/weight-regulating TFs to their target genes. Expression analysis and high-resolution quantitative trait loci (QTL) mapping suggested that OsMED15a is involved in rice seed development. OsMED15a has an N-terminal, three-helical KIX domain. Two of these helices, α1 and α3, and three amino acids, 76LRC78, within OsMED15a helix α3 were important for its interaction with several proteins, including interactions with the transactivation domains of two NAC-type TFs, OsNAC024 and OsNAC025. Moreover, OsMED15a, OsNAC024, and OsNAC025 all exhibited increased expression during seed development, and we identified several grain size/weight-associated SNPs in these genes in 509 low- and high-grain-weight rice genotypes. RNAi-mediated repression of OsMED15a expression down-regulated the expression of the grain size/weight regulating genes GW2, GW5 and DR11 and reduced grain length, weight, and yield. Of note, both OsNAC024 and OsNAC025 bound to the promoters of these three genes. We conclude that the transactivation domains of OsNAC024 and OsNAC025 target the KIX domain of OsMED15a in the regulation of grain size/weight-associated genes such as GW2, GW5, and D11. We propose that the integrated molecular-genetics approach used here could help identify networks of functional alleles of other regulator and co-regulator genes and thereby inform efforts for marker-assisted introgression of useful alleles in rice crop improvement.
This work was supported by the grant EMR/2015/001336 from Science and Engineering Research Board, Department of Science and Technology, Government of India and BT/BI/04/069/2006 for establishing the Distributed Information Sub Centre (DISC) from Department of Biotechnology (DBT) Government of India, at NIPGR. Authors are grateful to Dr. Nobutaka Mitsuda, Saitama University, Ibaraki, Japan, for luciferase reporter system. Authors thank Confocal Microscopy and Central Instrumentation facilities of NIPGR. We thank DBT-eLibrary Consortium for giving us access to literature. ND and PT was supported by fellowships from Council of Scientific and Industrial Research. SM and VK were supported by fellowships from University of Grant Commission, Government of India. MW acknowledges Short term Research Fellowship from NIPGR.
 
Date 2019-09-20T06:44:32Z
2019-09-20T06:44:32Z
2019
 
Type Article
 
Identifier Biochimica et Biophysica Acta (BBA) – Gene Regulatory Mechanisms, 1862(10): 194432
1874-9399
http://223.31.159.10:8080/jspui/handle/123456789/984
https://www.sciencedirect.com/science/article/pii/S1874939919300975?via%3Dihub
https://doi.org/10.1016/j.bbagrm.2019.194432
 
Language en_US
 
Format application/pdf
 
Publisher Elsevier B.V.