RT Journal Article
SR Electronic
T1 Type-A Arabidopsis Response Regulators Are Partially Redundant Negative Regulators of Cytokinin Signaling
JF The Plant Cell
JO Plant Cell
FD American Society of Plant Biologists
SP 658
OP 671
DO 10.1105/tpc.018978
VO 16
IS 3
A1 To, Jennifer P.C.
A1 Haberer, Georg
A1 Ferreira, Fernando J.
A1 Deruère, Jean
A1 Mason, Michael G.
A1 Schaller, G. Eric
A1 Alonso, Jose M.
A1 Ecker, Joseph R.
A1 Kieber, Joseph J.
YR 2004
UL http://www.plantcell.org/content/16/3/658.abstract
AB Type-A Arabidopsis (Arabidopsis thaliana) response regulators (ARRs) are a family of 10 genes that are rapidly induced by cytokinin and are highly similar to bacterial two-component response regulators. We have isolated T-DNA insertions in six of the type-A ARRs and constructed multiple insertional mutants, including the arr3,4,5,6,8,9 hextuple mutant. Single arr mutants were indistinguishable from the wild type in various cytokinin assays; double and higher order arr mutants showed progressively increasing sensitivity to cytokinin, indicating functional overlap among type-A ARRs and that these genes act as negative regulators of cytokinin responses. The induction of cytokinin primary response genes was amplified in arr mutants, indicating that the primary response to cytokinin is affected. Spatial patterns of ARR gene expression were consistent with partially redundant function of these genes in cytokinin signaling. The arr mutants show altered red light sensitivity, suggesting a general involvement of type-A ARRs in light signal transduction. Further, morphological phenotypes of some arr mutants suggest complex regulatory interactions and gene-specific functions among family members.