Multiple type-B response regulators mediate cytokinin signal transduction in Arabidopsis.
Type-B Arabidopsis thaliana response regulators (ARRs) are transcription factors that function in the final step of two-component signaling systems. To characterize their role in plant growth and development, we isolated T-DNA insertions within six of the genes (ARR1, ARR2, ARR10, ARR11, ARR12, and ARR18) from the largest subfamily of type-B ARRs and also constructed various double and triple combinations of these mutations. Higher order mutants revealed progressively decreased sensitivity to cytokinin, including effects on root elongation, lateral root formation, callus induction and greening, and induction of cytokinin primary response genes. The triple mutant arr1,10,12 showed almost complete insensitivity to cytokinin under many of the assay conditions used. By contrast, no significant change in the sensitivity to ethylene was found among the mutants examined. These results indicate that there is functional overlap among the type-B ARRs and that they act as positive regulators of cytokinin signal transduction.
Mason
Michael G
MG
Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA.
Mathews
Dennis E
DE
Argyros
D Aaron
DA
Maxwell
Bridey B
BB
Kieber
Joseph J
JJ
Alonso
Jose M
JM
Ecker
Joseph R
JR
Schaller
G Eric
GE
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D009154:Mutation / Q000502:physiology; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology
C117138:ARR1 protein, Arabidopsis; C469257:ARR10 protein, Arabidopsis; C473997:ARR11 protein, Arabidopsis; C117139:ARR2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D005030:Ethylenes; C036483:T-DNA; D014157:Transcription Factors; C036216:ethylene