The auxin responsive AP2/ERF transcription factor CROWN ROOTLESS5 is involved in crown root initiation in rice through the induction of OsRR1, a type‐A response regulator of cytokinin signaling
Open Access
- 11 April 2011
- journal article
- Published by Wiley in The Plant Journal
- Vol. 67 (3), 472-484
- https://doi.org/10.1111/j.1365-313x.2011.04610.x
Abstract
Cytokinin is known to have negative effects on de novo auxin-induced root formation. However, the regulatory mechanisms of root initiation by both cytokinin and auxin are poorly understood. In this study, we characterized a rice mutant, termed crown rootless5 (crl5), which produced fewer crown roots and displayed impaired initiation of crown root primordia. The expression of CRL5, which encodes a member of the large AP2/ERF transcription factor family protein, was observed in the stem region where crown root initiation occurs. Exogenous auxin treatment induced CRL5 expression without de novo protein biosynthesis, which also required the degradation of AUX/IAA proteins. A putative auxin response element in the CRL5 promoter region specifically interacted with a rice ARF, demonstrating that CRL5 may be a direct target of an ARF, similar to CRL1/ADVENTITIOUS ROOTLESS1 (ARL1) that also regulates crown root initiation. A crl1 crl5 double mutant displayed an additive phenotype, indicating that these two genes function in different genetic pathways for crown root initiation. In addition, ProACT:CRL5/WT showed a cytokinin-resistant phenotype for crown root initiation, and also up-regulated the expression of two negative regulators of cytokinin signaling, OsRR1 and OsRR2, which were downregulated in crl5. Transgenic plants that over-expressed OsRR1 under the control of the CRL5 promoter in a crl5 mutant background produced a higher number of crown roots than the crl5 plant. Taken together, these results indicate that auxin-induced CRL5 promotes crown root initiation through repression of cytokinin signaling by positively regulating type-A RR, OsRR1.Keywords
This publication has 51 references indexed in Scilit:
- AINTEGUMENTAandAINTEGUMENTA-LIKE6Act Redundantly to Regulate Arabidopsis Floral Growth and PatterningPlant Physiology, 2009
- The WUSCHEL-Related Homeobox GeneWOX11Is Required to Activate Shoot-Borne Crown Root Development in RicePlant Cell, 2009
- Cytokinin and auxin interaction in root stem-cell specification during early embryogenesisNature, 2008
- Cytokinins Act Directly on Lateral Root Founder Cells to Inhibit Root InitiationPlant Cell, 2007
- Cytokinins Determine Arabidopsis Root-Meristem Size by Controlling Cell DifferentiationCurrent Biology, 2007
- ARF7 and ARF19 Regulate Lateral Root Formation via Direct Activation ofLBD/ASLGenes inArabidopsisPlant Cell, 2007
- Identification and characterization of cytokinin-signalling gene families in riceGene, 2006
- Two-component circuitry in Arabidopsis cytokinin signal transductionNature, 2001
- Mutations in the AXR3 gene of Arabidopsis result in altered auxin response including ectopic expression from the SAUR‐AC1 promoterThe Plant Journal, 1996
- A Revised Medium for Rapid Growth and Bio Assays with Tobacco Tissue CulturesPhysiologia Plantarum, 1962