02022naa a2200181 a 450000100080000000500110000800800410001910000200006024501620008026000090024252014320025165000160168365000190169965000200171870000190173870000190175777300640177615772232026-01-15       2008    bl uuuu     u00u1 u    #d1 aWOHLBACH, D. J.  aAnalysis of the arabidopsis histidine kinase ATHK1 reveals a connection between vegetative osmotic stress sensing and seed maturation.h[electronic resource]  c2008  aTocopewithwaterstress,plantsmustbeabletoeffectivelysense,respondto,andadapttochangesinwateravailability.The Arabidopsis thaliana plasma membrane His kinase ATHK1 has been suggested to act as an osmosensor that detects water stress and initiates downstream responses. Here, we provide direct genetic evidence that ATHK1 not only is involved in the water stress response during early vegetative stages of plant growth but also plays a unique role in the regulation of desiccation processesduringseedformation.Tomorecomprehensivelyidentifygenesinvolvedinthedownstreampathways affected by theATHK1-mediatedresponsetowaterstress,wecreatedalarge-scalesummaryofexpressiondata,termedthe AtMegaCluster. In the AtMegaCluster, hierarchical clustering techniques were used to compare whole-genome expression levels inathk1mutantswiththeexpressionlevelsreportedinpubliclyavailabledatasetsofArabidopsistissuesgrownundera wide variety of conditions. These experiments revealed that ATHK1 is cotranscriptionally regulated with several Arabidopsis response regulators, together with two proteins containing novel sequences. Since overexpression of ATHK1 results in increased water stress tolerance, our observations suggest a new top-down route to increasing drought resistance via receptor-mediated increases in sensing water status, rather than through genetically engineered changes in downstream transcription factors or specific osmolytes.  aArabidopsis  aOsmotic stress  aSeed maturation1 aQUIRINO, B. F.1 aSUSSMAN, M. R.  tThe Plant Cell, Rockville-MDgv.20, n.4, p.1101-1117, 2008.