Cold Spring Harbor, NY -- The normal development of an animal or plant can be compared in at least two ways with the successful performance of a great symphony. The whole is the product of a great number of events involving contributions by many different "players"; and these contributions must occur in a precise and almost perfectly coordinated temporal and spatial sequence.
In simple animals like the fruit fly and more recently in plants and mammals, scientists have been able to identify some of the principal players in the developmental symphony. Today, a team of researchers from Cold Spring Harbor Laboratory (CSHL) explains for the first time the operation of a mechanism in plants that controls a class of key developmental regulatory genes, called homeobox genes.
The homeobox genes under study, called BREVIPEDICELLUS (BP) and KNAT2, need to be active in plant stem cells in order for the cells to maintain their non-specialized character. Stem cells are totipotent: they can develop, or "differentiate," into any plant cell type, depending on signals they receive which send them down the developmental path. When the moment is just right for plant organs such as leaves to begin to grow, BP and KNAT2 are switched off so that development can proceed.
"We were already familiar with the players in this regulatory mechanism, which have been conserved, or preserved, by evolution across species from flies to plants to animals," says CSHL Professor Marja Timmermans, who led the research team. "What we have not understood until now is how, in plants, the action of the players is very precisely coordinated in time and space."
It turns out that a highly conserved assembly of polycomb proteins, called Polycomb-repressive complex2 (PRC2), spurs a process called epigenetic regulation that physically marks targeted genes in this case, BP and KNAT2 for repression. But how do these protein complexes know where along the plant cell's
|Contact: Peter Tarr|
Cold Spring Harbor Laboratory