Abstract
Mediator complex, a conserved multi-protein, is necessary for controlling RNA polymerase II (Pol II) transcription in eukaryotes. Given little is known about them in tomato, a tomato Mediator subunit 18 gene was isolated and named SlMED18. To further explore the function of SlMED18, the transgenic tomato plants targeting SlMED18 by RNAi-mediated gene silencing were generated. The SlMED18-RNAi lines exhibited multiple developmental defects, including smaller size and slower growth rate of plant and significantly smaller compound leaves. The contents of endogenous bioactive GA3 in SlMED18 silenced lines were slightly less than that in wild type. Furthermore, qRT-PCR analysis indicated that expression of gibberellins biosynthesis genes such as SlGACPS and SlGA20x2, auxin transport genes (PIN1, PIN4, LAX1 and LAX2) and several key regulators, KNOX1, KNOX2, PHAN and LANCEOLATE(LA), which involved in the leaf morphogenesis were significantly down-regulated in SlMED18-RNAi lines. These results illustrated that SlMED18 plays an essential role in regulating plant internode elongation and leaf expansion in tomato plants and it acts as a key positive regulator of gibberellins biosynthesis and signal transduction as well as auxin proper transport signalling. These findings are the basis for understanding the function of the individual Mediator subunits in tomato.
Highlights
Plant growth and development, including vegetative growth and reproductive growth, is a multiphase process that requires a tight coordination among molecular, biochemical and structural elements[1]
Sequencing validation indicated that the correct gene sequence was obtained and sequence analysis showed that SlMED18 contains an open reading frame (ORF) of 651 bp and encodes 216 amino acid residues
Phylogenic analysis implied that sequences are weakly conserved between S. cerevisiae, Human (Hs) and plants, but they are conserved across the plant kingdom (Fig. 1A,B)
Summary
Plant growth and development, including vegetative growth and reproductive growth, is a multiphase process that requires a tight coordination among molecular, biochemical and structural elements[1]. The regulation of plant gene expression is necessary for the normal growth and development of plants, which is a complex and accurate network system that generally includes both transcription and translation of a series of genes. Mediator, a multi-subunit complex, is one cofactor that promotes transcription initiation as the bridges between transcription activators bounding to regulatory upstream promoter or enhances DNA elements and the RNA Pol II general transcriptional machinery at the essential promoter[8,9,10,11]. There are some studies on the Mediator function in model plant which made some meaningful progress, the roles of plant mediator in RNA transcription remain to be further elucidated on account of the lack of relevant mutant gene material
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
