1. Natural variation in epigenetic pathways affects the specification of female gamete precursors in Arabidopsis.
- Author
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Rodríguez-Leal D, León-Martínez G, Abad-Vivero U, and Vielle-Calzada JP
- Subjects
- Arabidopsis metabolism, Arabidopsis Proteins genetics, Arabidopsis Proteins metabolism, Argonaute Proteins genetics, Argonaute Proteins metabolism, Cell Differentiation genetics, Cell Differentiation physiology, Gametogenesis, Plant genetics, Gametogenesis, Plant physiology, Gene Expression Regulation, Plant genetics, Gene Expression Regulation, Plant physiology, RNA-Dependent RNA Polymerase genetics, RNA-Dependent RNA Polymerase metabolism, Arabidopsis genetics, Arabidopsis physiology, Epigenesis, Genetic genetics
- Abstract
In angiosperms, the transition to the female gametophytic phase relies on the specification of premeiotic gamete precursors from sporophytic cells in the ovule. In Arabidopsis thaliana, a single diploid cell is specified as the premeiotic female gamete precursor. Here, we show that ecotypes of Arabidopsis exhibit differences in megasporogenesis leading to phenotypes reminiscent of defects in dominant mutations that epigenetically affect the specification of female gamete precursors. Intraspecific hybridization and polyploidy exacerbate these defects, which segregate quantitatively in F2 populations derived from ecotypic hybrids, suggesting that multiple loci control cell specification at the onset of female meiosis. This variation in cell differentiation is influenced by the activity of ARGONAUTE9 (AGO9) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6), two genes involved in epigenetic silencing that control the specification of female gamete precursors. The pattern of transcriptional regulation and localization of AGO9 varies among ecotypes, and abnormal gamete precursors in ovules defective for RDR6 share identity with ectopic gamete precursors found in selected ecotypes. Our results indicate that differences in the epigenetic control of cell specification lead to natural phenotypic variation during megasporogenesis. We propose that this mechanism could be implicated in the emergence and evolution of the reproductive alternatives that prevail in flowering plants., (© 2015 American Society of Plant Biologists. All rights reserved.)
- Published
- 2015
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