tailieunhanh - Báo cáo y học: "Cytokinin and auxin intersection in root meristems"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Minireview cung cấp cho các bạn kiến thức về ngành y đề tài: Cytokinin and auxin intersection in root meristems. | Minireview Cytokinin and auxin intersection in root meristems Elisabeth J Chapman and Mark Estelle Address Division of Biology 9500 Gilman Drive La Jolla CA 92093-0116 USA. Correspondence Mark Estelle. Email mestelle@ Published 23 February 2009 Genome Biology 2009 10 210 doi gb-2009-l0-2-2l0 The electronic version of this article is the complete one and can be found online at http 2009 l0 2 2l0 2009 BioMed Central Ltd Abstract The hormone cytokinin promotes cell differentiation in plant roots by repressing both auxin transport and responses to auxin at the boundary between the meristem and the root elongation zone. In plants populations of undifferentiated cells called meristems serve as the source of all new growth throughout post-embryonic development. Meristem size or the number of undifferentiated cells in the meristem is maintained by balancing stem-cell replenishment through cell division with cell differentiation and elongation to form new tissues and organs. In the Arabidopsis root meristem maintenance is controlled by the small-molecule hormones auxin and cytokinin which affect cell division and cell elongation. Although auxin and cytokinin have long been known to interact during development the molecular mechanisms of these interactions have been elusive. In a recent issue of Science Sabrina Sabatini and colleagues Dello Ioio et al. 1 have elucidated a simple molecular mechanism by which cytokinin regulates meristem size in the Arabidopsis root by antagonizing auxin signaling in the transition zone the region where cells leave the meristem to differentiate and elongate. Auxin and cytokinin have contrasting roles in root meristems. Auxin is required for meristem cell division application of exogenous auxin increases root meristem size for example whereas cytokinin reduces it 2 3 . Basipetal transport and lateral distribution of auxin are required for stem-cell replenishment as plants carrying mutations in three members of