The shoot meristems of plants comprise stem cells, peripheral derivatives and primordial initials from which leaves, branches and flowers arise. Ramosa1 in maize and symmetric Leaves1 (AS1) in Arabidopsis inhibit stem cell fate mediated by Ramosa2 in maize, which is an AS1 target in Arabidopsis. AS1 coats mitotic chromosomes indicating a role for chromatin which Professor Martienssen is examining using profiling and genetic analysis. His research has shown that RNA interference maintains heterochromatin during S phase which has implications for stem cell proliferation and renewal in both animals and plants.
Kloc, A., Zaratiegui, M., Nora, E., and Martienssen, R. (2008). RNA Interference Guides Histone Modification During the S Phase of Chromosomal Replication. Curr. Biol. 18: 490-495.
Garcia D, Collier SA, Byrne ME, Martienssen RA. Specification of leaf polarity in Arabidopsis via the trans-acting siRNA pathway. Curr Biol. 2006 May 9;16(9):933-8.
Vollbrecht E, Springer PS, Goh L, Buckler ES 4th, Martienssen R. Architecture of floral branch systems in maize and related grasses. Nature. 2005 Aug 25;436(7054):1119-26.