The evolution of WRKY transcription factors

BMC Plant Biology

Research Article

Prateek Tripathi¹  Qingxi J Shen²  Charles I Rinerson³  Paul J Rushton³  Roel C Rabara³ 

[1] Molecular and Computational Biology Section, Dana & David Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, CA, USA;School of Life Sciences, University of Nevada, 89154, Las Vegas, USA;Texas A&M AgriLife Research and Extension Center, 75252, Dallas, Texas, USA;

关键词: WRKY transcription factor;    Evolution;    Lateral gene transfer;    Resistance protein;    Charophyte;   

DOI  :  10.1186/s12870-015-0456-y

 received in 2014-11-26, accepted in 2015-02-13,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundThe availability of increasing numbers of sequenced genomes has necessitated a re-evaluation of the evolution of the WRKY transcription factor family. Modern day plants descended from a charophyte green alga that colonized the land between 430 and 470 million years ago. The first charophyte genome sequence from Klebsormidium flaccidum filled a gap in the available genome sequences in the plant kingdom between unicellular green algae that typically have 1-3 WRKY genes and mosses that contain 30-40. WRKY genes have been previously found in non-plant species but their occurrence has been difficult to explain.ResultsOnly two WRKY genes are present in the Klebsormidium flaccidum genome and the presence of a Group IIb gene was unexpected because it had previously been thought that Group IIb WRKY genes first appeared in mosses. We found WRKY transcription factor genes outside of the plant lineage in some diplomonads, social amoebae, fungi incertae sedis, and amoebozoa. This patchy distribution suggests that lateral gene transfer is responsible. These lateral gene transfer events appear to pre-date the formation of the WRKY groups in flowering plants. Flowering plants contain proteins with domains typical for both resistance (R) proteins and WRKY transcription factors. R protein-WRKY genes have evolved numerous times in flowering plants, each type being restricted to specific flowering plant lineages. These chimeric proteins contain not only novel combinations of protein domains but also novel combinations and numbers of WRKY domains. Once formed, R protein WRKY genes may combine different components of signalling pathways that may either create new diversity in signalling or accelerate signalling by short circuiting signalling pathways.ConclusionsWe propose that the evolution of WRKY transcription factors includes early lateral gene transfers to non-plant organisms and the occurrence of algal WRKY genes that have no counterparts in flowering plants. We propose two alternative hypotheses of WRKY gene evolution: The “Group I Hypothesis” sees all WRKY genes evolving from Group I C-terminal WRKY domains. The alternative “IIa + b Separate Hypothesis” sees Groups IIa and IIb evolving directly from a single domain algal gene separate from the Group I-derived lineage.

【 授权许可】

Unknown   
© Rinerson et al.; licensee BioMed Central. 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.