Stem Cell Regulation by Arabidopsis WOX Genes.
Gene amplification followed by functional diversification is a major force in evolution. A typical example of this is seen in the WUSCHEL-RELATED HOMEOBOX (WOX) gene family, named after the Arabidopsis stem cell regulator WUSCHEL. Here we analyze functional divergence in the WOX gene family. Members of the WUS clade, except the cambium stem cell regulator WOX4, can substitute for WUS function in shoot and floral stem cell maintenance to different degrees. Stem cell function of WUS requires a canonical WUS-box, essential for interaction with TPL/TPR co-repressors, whereas the repressive EAR domain is dispensable and the acidic domain seems only to be required for female fertility. In contrast to the WUS clade, members of the ancient WOX13 and the WOX9 clades cannot support stem cell maintenance. Although the homeodomains are interchangeable between WUS and WOX9 clade members, a WUS-compatible homeodomain together with canonical WUS-box is not sufficient for stem cell maintenance. Our results suggest that WOX function in shoot and floral meristems of Arabidopsis is restricted to the modern WUS clade, suggesting that stem cell control is a derived function. Yet undiscovered functional domains in addition to the homeodomain and the WUS-box are necessary for this function.
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany. Electronic address: alicja.dolzblasz@uwr.edu.pl.
Alicja
A
Dolzblasz
Institute of Developmental Biology, Biocenter Cologne, Universität zu Köln, Zülpicher Street 47b, 50674 Köln, Germany.
Judith
J
Nardmann
Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK.
Elena
E
Clerici
Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK.
Barry
B
Causier
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany.
Eric
E
van der Graaff
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany.
Jinhui
J
Chen
Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK.
Brendan
B
Davies
Institute of Developmental Biology, Biocenter Cologne, Universität zu Köln, Zülpicher Street 47b, 50674 Köln, Germany.
Wolfgang
W
Werr
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany. Electronic address: laux@biologie.uni-freiburg.de.
Thomas
T
Laux
D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000166:cytology / Q000378:metabolism; D018520:Plant Shoots / Q000166:cytology / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism* / Q000502:physiology
D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; C581875:WOX4 protein, Arabidopsis; C116421:WUSCHEL protein, Arabidopsis
Arabidopsis thaliana; WOX genes; WUSCHEL; shoot meristem; stem cells