Control of trichome branching by chromatin assembly factor-1.
BACKGROUND
Chromatin dynamics and stability are both required to control normal development of multicellular organisms. Chromatin assembly factor CAF-1 is a histone chaperone that facilitates chromatin formation and the maintenance of specific chromatin states. In plants and animals CAF-1 is essential for normal development, but it is poorly understood which developmental pathways require CAF-1 function.


RESULTS
Mutations in all three CAF-1 subunits affect Arabidopsis trichome morphology and lack of CAF-1 function results in formation of trichomes with supernumerary branches. This phenotype can be partially alleviated by external sucrose. In contrast, other aspects of the CAF-1 mutant phenotype, such as defective meristem function and organ formation, are aggravated by external sucrose. Double mutant analyses revealed epistatic interactions between CAF-1 mutants and stichel, but non-epistatic interactions between CAF-1 mutants and glabra3 and kaktus. In addition, mutations in CAF-1 could partly suppress the strong overbranching and polyploidization phenotype of kaktus mutants.


CONCLUSIONS
CAF-1 is required for cell differentiation and regulates trichome development together with STICHEL in an endoreduplication-independent pathway. This function of CAF-1 can be partially substituted by application of exogenous sucrose. Finally, CAF-1 is also needed for the high degree of endoreduplication in kaktus mutants and thus for the realization of kaktus' extreme overbranching phenotype.
Exner
Vivien
V
Institute of Plant Sciences & Zurich-Basel Plant Science Center, ETH Zurich, CH-8092 Zurich, Switzerland. vexner@ethz.ch
Gruissem
Wilhelm
W
Hennig
Lars
L
D017360:Arabidopsis / Q000033:anatomy & histology* / Q000166:cytology / Q000187:drug effects / Q000235:genetics; D029681:Arabidopsis Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D056504:Chromatin Assembly Factor-1; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D018744:DNA, Plant / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004843:Epistasis, Genetic; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006657:Histones / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000166:cytology / Q000187:drug effects; D011003:Ploidies; D013395:Sucrose / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
D029681:Arabidopsis Proteins; D056504:Chromatin Assembly Factor-1; D002868:Chromosomal Proteins, Non-Histone; D018744:DNA, Plant; D004268:DNA-Binding Proteins; C422044:FAS protein, Arabidopsis; D006657:Histones; C474076:STICHEL protein, Arabidopsis; D013395:Sucrose