Novel and expanded roles for MAPK signaling in Arabidopsis stomatal cell fate revealed by cell type-specific manipulations.
Mitogen-activated protein kinase (MAPK) signaling networks regulate numerous eukaryotic biological processes. In Arabidopsis thaliana, signaling networks that contain MAPK kinases MKK4/5 and MAPKs MPK3/6 function in abiotic and biotic stress responses and regulate embryonic and stomatal development. However, how single MAPK modules direct specific output signals without cross-activating additional downstream processes is largely unknown. Studying relationships between MAPK components and downstream signaling outcomes is difficult because broad experimental manipulation of these networks is often lethal or associated with multiple phenotypes. Stomatal development in Arabidopsis follows a series of discrete, stereotyped divisions and cell state transitions. By expressing a panel of constitutively active MAPK kinase (MAPKK) variants in discrete stomatal lineage cell types, we identified a new inhibitory function of MKK4 and MKK5 in meristemoid self-renewal divisions. Furthermore, we established roles for MKK7 and MKK9 as both negative and (unexpectedly) positive regulators during the major stages of stomatal development. This has expanded the number of known MAPKKs that regulate stomatal development and allowed us to build plausible and testable subnetworks of signals. This in vivo cell type-specific assay can be adapted to study other protein families and thus may reveal insights into other complex signal transduction pathways in plants.
Lampard
Gregory R
GR
Department of Biology, Stanford University, Stanford, CA 94305, USA.
Lukowitz
Wolfgang
W
Ellis
Brian E
BE
Bergmann
Dominique C
DC
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001681:Biological Assay / Q000379:methods; D019521:Body Patterning / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics*; D002455:Cell Division / Q000235:genetics; D019070:Cell Lineage / Q000235:genetics*; D049109:Cell Proliferation; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D006131:Growth Inhibitors / Q000235:genetics / Q000378:metabolism; D048688:MAP Kinase Kinase 7 / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000235:genetics*; D018519:Meristem / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D054046:Plant Stomata / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development
D029681:Arabidopsis Proteins; D006131:Growth Inhibitors; D020928:Mitogen-Activated Protein Kinases; C512166:BUD1 protein, Arabidopsis; D048688:MAP Kinase Kinase 7; C519871:MKK4 protein, Arabidopsis; C519872:MKK5 protein, Arabidopsis; C527379:MKK9 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases