KNOXLost theOX: TheArabidopsis KNATMGene Defines a Novel Class of KNOX Transcriptional Regulators Missing the Homeodomain

Magnani, Enrico; Hake, Sarah

doi:10.1105/tpc.108.058495

Cited by 120 publications

(148 citation statements)

References 47 publications

(57 reference statements)

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“…To add further complexity to the network, a recently discovered KNOX protein lacking the DNA-binding domain competes for interacting factors (Magnani and Hake, 2008). Our results indicate that the induction of CUC1 is relatively specific to STM levels, although the closely related KNAT1 could also rapidly induce CUC1 when fused to the VP16 domain.…”

Section: Targets Of the Knoxi Transcription Factorsmentioning

confidence: 85%

A Mechanistic Link betweenSTMandCUC1during Arabidopsis Development

Spinelli

Martín²,

Viola³

et al. 2011

Plant Physiology

120

101

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The KNOXI transcription factor SHOOT MERISTEMLESS (STM) is required to establish and maintain the Arabidopsis (Arabidopsis thaliana) apical meristem, yet little is known about its direct targets. Using different approaches we demonstrate that the induction of STM causes a significant up-regulation of the organ boundary gene CUP SHAPED COTYLEDON1 (CUC1), which is specific and independent of other meristem regulators. We further show that the regulation of CUC1 by STM is direct and identify putative binding sites in its promoter. Continuous expression of STM in Arabidopsis leaf primordia also causes the activation of CUC2-3, as well as microRNA MIR164a, which provides a negative feedback loop by posttranscriptionally regulating CUC1 and CUC2. The results bring new insights into the mechanistic links between KNOXI and CUC transcription factors and contribute to the understanding of the regulatory network controlled by STM.

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Section: Targets Of the Knoxi Transcription Factorsmentioning

confidence: 85%

A Mechanistic Link betweenSTMandCUC1during Arabidopsis Development

Spinelli

Martín²,

Viola³

et al. 2011

Plant Physiology

120

101

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“…Amino acid sequence comparison indicated that the FCL1 protein shares a high sequence similarity with the Arabidopsis KNATM-B (63% similarities and 43% identities) and tomato PTS/TKD1 (60% similarities and 48% identities), two recently identified class M homeodomainless KNOX proteins in Arabidopsis and tomato, respectively Magnani and Hake, 2008) (Figure 2H). Neighborjoining, maximum parsimony, and UPGMA phylogenetic tree (D) Orientation and exon-intron structures of 12 annotated ORFs within the common deletion region in fcl1-1 and fcl1-2 alleles.…”

Section: Truncatula Fcl1 Encodes a Class M Knox Proteinmentioning

confidence: 96%

“…It has been shown that the class M KNOX genes function to interfere with the canonical KNOXI activity by titrating proteinprotein interactions involving KNOXI and its interacting partners, BEL1-like (BELL) proteins, and by regulating nuclear localization of KNOXI-BELL complexes. However, the role of class M KNOXI in leaf development remains to be elucidated, since neither lossof-function mutants nor knockdown mutants have been isolated in Arabidopsis and tomato Magnani and Hake, 2008). Here, we report the isolation and characterization of loss-of-function fused compound leaf1 (fcl1) mutants from M. truncatula.…”

Section: Introductionmentioning

confidence: 99%

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Regulation of Compound Leaf Development in Medicago truncatula by Fused Compound Leaf1, a Class M KNOX Gene

Jisheng

Wang

et al. 2011

The Plant Cell

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Medicago truncatula is a legume species belonging to the inverted repeat lacking clade (IRLC) with trifoliolate compound leaves. However, the regulatory mechanisms underlying development of trifoliolate leaves in legumes remain largely unknown. Here, we report isolation and characterization of fused compound leaf1 (fcl1) mutants of M. truncatula. Phenotypic analysis suggests that FCL1 plays a positive role in boundary separation and proximal-distal axis development of compound leaves. Map-based cloning indicates that FCL1 encodes a class M KNOX protein that harbors the MEINOX domain but lacks the homeodomain. Yeast two-hybrid assays show that FCL1 interacts with a subset of Arabidopsis thaliana BEL1-like proteins with slightly different substrate specificities from the Arabidopsis homolog KNATM-B. Double mutant analyses with M. truncatula single leaflet1 (sgl1) and palmate-like pentafoliata1 (palm1) leaf mutants show that fcl1 is epistatic to palm1 and sgl1 is epistatic to fcl1 in terms of leaf complexity and that SGL1 and FCL1 act additively and are required for petiole development. Previous studies have shown that the canonical KNOX proteins are not involved in compound leaf development in IRLC legumes. The identification of FCL1 supports the role of a truncated KNOX protein in compound leaf development in M. truncatula.

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“…Conversely, a reduction in the expression of STM-like genes in compound-leafed species reduces leaf complexity (Hay and Tsiantis, 2006). The function of STM in leaf morphology is in part controlled by its interaction with the truncated form of the KNOX1 factor PETROSELINUM/KNOX ARABI-DOPSIS THALIANA MEINOX (PTS/KNATM) through competition for the formation of dimers with BEL-LIKE (BELL) homeodomain (HD) factors (Kimura et al, 2008;Magnani and Hake, 2008). KNOX1 levels also can be controlled at the network level by upstream factors in the PTS network module (Ichihashi et al, 2014).…”

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confidence: 99%

Transcriptional, Posttranscriptional, and Posttranslational Regulation of SHOOT MERISTEMLESS Gene Expression in Arabidopsis Determines Gene Function in the Shoot Apex

et al. 2014

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The activity of SHOOT MERISTEMLESS (STM) is required for the functioning of the shoot apical meristem (SAM). STM is expressed in the SAM but is down-regulated at the site of leaf initiation. STM is also required for the formation of compound leaves. However, how the activity of STM is regulated at the transcriptional, posttranscriptional, and posttranslational levels is poorly understood. We previously found two conserved noncoding sequences in the promoters of STM-like genes across angiosperms, the K-box and the RB-box. Here, we characterize the function of the RB-box in Arabidopsis (Arabidopsis thaliana). The RB-box, along with the K-box, regulates the expression of STM in leaf sinuses, which are areas on the leaf blade with meristematic potential. The RB-box also contributes to restrict STM expression to the SAM. We identified FAR1-RELATED SEQUENCES-RELATED FACTOR1 (FRF1) as a binding factor to the RB-box region. FRF1 is an uncharacterized member of a subfamily of four truncated proteins related to the FAR1-RELATED SEQUENCES factors. Internal deletion analysis of the STM promoter identified a region required to repress the expression of STM in hypocotyls. Expression of STM in leaf primordia under the control of the JAGGED promoter produced plants with partially undifferentiated leaves. We further found that the ELK domain has a role in the posttranslational regulation of STM by affecting the nuclear localization of STM.

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KNOXLost theOX: TheArabidopsis KNATMGene Defines a Novel Class of KNOX Transcriptional Regulators Missing the Homeodomain

Cited by 120 publications

References 47 publications

A Mechanistic Link betweenSTMandCUC1during Arabidopsis Development

A Mechanistic Link betweenSTMandCUC1during Arabidopsis Development

Regulation of Compound Leaf Development in Medicago truncatula by Fused Compound Leaf1, a Class M KNOX Gene

Transcriptional, Posttranscriptional, and Posttranslational Regulation of SHOOT MERISTEMLESS Gene Expression in Arabidopsis Determines Gene Function in the Shoot Apex

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