Plant stem cell signaling involves ligand-dependent trafficking of the XXXX receptor kinase.

@entity24637 @entity958 @entity3588 @entity30456 @entity30457
BACKGROUND: Cell numbers in above-ground meristems of plants are thought to be maintained by a feedback loop driven by perception of the glycopeptide ligand @entity30457 ( @entity30457 ) by the @entity24637 ( @entity24637 ) receptor kinase and the @entity3588 /CORYNE (CRN) receptor-like complex. @entity30457 produced in the stem cells at the meristem apex limits the expression level of the stem cell-promoting homeodomain protein @entity30456 ( @entity30456 ) in the cells beneath, where @entity24637 and @entity30456 RNA are localized. @entity30456 downregulation nonautonomously reduces stem cell proliferation. Overexpression of @entity30457 eliminates the stem cells, causing meristem termination, and loss of @entity30457 function allows meristem overproliferation. There are many questions regarding the @entity30457 / @entity24637 interaction, including where in the meristem it occurs, how it is regulated, and how it is that a large range of @entity30457 concentrations gives no meristem size phenotype. RESULTS: Here we use genetics and live imaging to examine the cell biology of @entity24637 in @entity958 meristematic tissue. We demonstrate that plasma membrane-localized @entity24637 is reduced in concentration by @entity30457 , which causes trafficking of @entity24637 to lytic vacuoles. We find that changes in @entity3588 activity have no detectable effects on @entity24637 levels. We also find that @entity30457 appears to diffuse broadly in meristems, contrary to a recent sequestration model. CONCLUSIONS: This study provides a new model for @entity24637 function in plant stem cell maintenance and suggests that downregulation of plasma membrane-localized @entity24637 by its @entity30457 ligand can account for the buffering of @entity30457 signaling in the maintenance of stem cell pools in plants.
