email martiens@cshl.edu, phone (516) 367-8322, fax (516) 367-8369

Epigenetic mechanisms of gene regulation impact genome organization and inheritance, as well as the specification and maintenance of cell fate. These mechanisms are conserved in eukaryotes and provide an additional layer of information superimposed on the genetic code. We are using model plants and yeast to investigate epigenetic mechanisms of transposon silencing, gene regulation and stem cell fate via functional genomics and developmental genetics. In fission yeast, we have found that centromeric repeats are transcribed, and are targets of RNA interference (RNAi). Small RNAs derived from these repeats guide histone H3 lysine 9 methylation, heterochromatin formation, and chromosome segregation. We have demonstrated parallel mechanisms in plants, by using Arabidopsis chromosomal microarrays to investigate patterns of DNA methylation, chromatin remodeling and RNAi on transposons and heterochromatin.

We are investigating stem cell function in plants by characterizing asymmetric leaves1, bellringer, and argonaute in Arabidopsis and ramosa 1 in maize. ARGONAUTE has an important role in RNAi, and small RNA appears to act as a signal to specify leaf polarity.
Our research in plant genomics, includes studies on polyploidy, chromatin organization, DNA replication and chromatin profiling, and maize inflorescence architecture. With our collaborators, we are investigating the origin of seed plants by studying the genomes of primitive gymnosperms.

We maintain an efficient system for site-selected transposon mutagenesis in maize (http://mtm.cshl.edu) and a collection of 40,000 gene trap and enhancer trap lines in Arabidopsis (http://genetrap.cshl.edu).

Irvine, D., Zaratiegui, M., Tolia, N.H., Chitwood, D., Goto, D., Vaughn, M., Joshua-Tor, L., and Martienssen, R. 2006. Argonaute slicing is required for heterochromatic silencing and spreading. Science 313: 1134–1137.

Vollbrecht, E., Springer, P.S., Goh, L., Buckler, E., and Martienssen, R. 2005. Architecture of floral branch systems in maize and related grasses. Nature 436: 1119–1126.

Lippman, Z., Gendrel, A.-V., Black, M., Vaughn, M., Dedhia, N., McCombie, W.R., Lavine, K., Mittal, V., May, B., Kasschau, K., Carrington, J.C., Doerge, R.W., Colot, V., and Martienssen, R. 2004. Role of transposable elements in heterochromatin and epigenetic control. Nature 430: 471–476.

Kidner, C.A., and Martienssen, R.A. 2004. Spatially restricted microRNA directs leaf polarity through ARGONAUTE1. Nature 428: 81–84.