<i>KNAT1</i> and <i>ERECTA</i> Regulate Inflorescence Architecture in Arabidopsis

Douglas, Scott J.; Chuck, George; Dengler, Ronald E.; Pelecanda, Lakshmi; Riggs, C. Daniel

doi:10.1105/tpc.010391

Cited by 221 publications

(197 citation statements)

References 34 publications

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“…Our results strongly indicate that all KNOX and BELL proteins recognize the same DNA-binding motif; however, genetic and molecular evidence in Arabidopsis suggests that STM and KNAT1 control different developmental pathways (3,4,47). Even if there is functional overlap between these two knox genes, it is difficult to explain how they control different pathways (i.e., target genes) yet bind to the same DNA sequence.…”

Section: Discussionmentioning

confidence: 49%

Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Smith

Boschke

Hake

2002

Proc. Natl. Acad. Sci. U.S.A.

160

166

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Understanding molecular mechanisms that control cell fate in the shoot apical meristem is a fundamental question in plant development. Genetic and molecular studies demonstrate that maize KNOTTED1 (KN1) of the TALE (3-aa acid loop extension) class of homeodomain (HD) proteins is involved in shoot apical meristem function. We show that KN1 interacts with knotted interacting protein (KIP), a BEL1-like TALE HD protein. Interaction between KN1 and KIP is mediated by conserved domains in the N termini of both proteins. The KN1 DNA-binding sequence, TGACAG(G͞C)T, was biochemically identified, and in vitro DNA-binding assays show that individually KN1 and the HD of KIP bind specifically to this motif with low affinity. The KN1-KIP complex, however, binds specifically to this DNA-binding motif with high affinity, indicating that the association of KN1 and KIP may function in transcriptional regulation. In plants, development of the aerial shoot is controlled by a group of cells in the shoot apex called the shoot apical meristem (SAM). The SAM is the site where organogenesis is initiated and from which leaves, flowers, or other determinate structures are produced. Because plant development is a continuous process, the SAM must balance the process of differentiation and maintenance to allow growth.Maize knotted1 (kn1) and the Arabidopsis ortholog SHOOT-MERISTEMLESS (STM) are members of the knox family of genes that are required for SAM function (1). The expression of kn1 and STM is restricted to the indeterminate cells of the SAM. Moreover, this pattern of expression is excluded from the zone of the SAM that gives rise to organs (2, 3). Loss-of-function mutations in kn1 and STM produce a shootless phenotype, where the SAM prematurely terminates after initiating cotyledons, demonstrating that kn1 and STM function in meristem maintenance (3-5). In backgrounds where some shoot formation occurs, organ production is reduced, indicating that vegetative and inflorescence meristems are compromised (4,(6)(7)(8). In addition to maintenance functions, class 1 knox genes, including kn1, are capable of respecifying cell fates when ectopically expressed in the leaf (1). Studies that support this hypothesis come from analysis of dominant mutations in the maize knox genes, kn1, rough sheath1 (rs1), liguleless3 (lg3), and gnarley1 (gn1) (9-12). Each of these phenotypes is caused by ectopic leaf expression, resulting in proximal leaf cell identities transposed distally into the blade (1, 13).The knox gene family was the first group of plant genes identified that encodes homeodomain (HD) proteins (14). In animals, HD-containing proteins function as transcription factors that are important regulators of animal cell fate and development (15). The HD is a conserved structure that contains three ␣ helices, and a sequence motif in the third helix recognizes and binds to the appropriate DNA sequence (15). Amino acid sequence comparison studies have subdivided the HD family into two classes of proteins: the typical HD class and the TALE (3-aa loop...

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Section: Discussionmentioning

confidence: 49%

Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Smith

Boschke

Hake

2002

Proc. Natl. Acad. Sci. U.S.A.

160

166

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“…It has been suggested that coordinated cell division and differentiation in plant SAMs is controlled by different classes of receptor kinases (Dievart and Clark 2004;Shiu et al 2004) that include the CLV family of proteins (Stahl and Simon 2005) and ERECTA (Torii et al 1996;Laufs et al 1998;Yokoyama et al 1998;Douglas et al 2002;Shpak et al 2003;Woodward et al 2005). The Clavata1-like protein Gma.7646.1.A1_at was up-regulated in the soybean SAM and we found that the most similar Arabidopsis orthologue of this gene was AT5G51560, which is annotated as encoding leucine-rich transmembrane protein kinase.…”

Section: Receptor Kinases and Cell Signallingmentioning

confidence: 89%

Genome-wide analysis of gene expression in soybean shoot apical meristem

et al. 2008

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The shoot apical meristem (SAM) contains undifferentiated stem cells that are responsible for the initiation of above-ground organs. The nature of genetic programs and the regulatory networks underlying SAM function in a major legume crop, soybean was investigated here. We used soybean GeneChip (containing 37,744 probe sets) to examine the transcript profiles associated with micro-dissected, actively growing SAMs or growth arrested axillary meristems (AMs) experiencing apical dominance, in comparison to that of non-meristem (NM) tissue. A total of 1,090 and 1,523 transcripts were identified to be significantly up- or down-regulated in the SAM in comparison to the NM. RT-PCR and in situ hybridization analysis were also carried out to verify the experimental approach. The resulting gene expression profiles point to the combinatorial role of diverse regulatory pathways including those associated with cell division and proliferation, epigenetic regulation, auxin-mediated responses and microRNA regulation in meristem function. In situ hybridization analysis on selected transcripts has implicated their roles in SAM maintenance and the establishment of organ polarity. We also identified a gene, ANGUSITFOLIA3 that could potentially serve as a novel marker for differentiating cells in the meristem. Computational analysis on the promoter regions of Arabidopsis thaliana orthologs of genes with high expression in the soybean SAM revealed a conserved over-representation of three cis-acting regulatory motifs. Our data show that plant meristems possess a unique transcriptional profile, with shared "molecular signatures" in apical and axillary meristems providing a rich source of novel target genes for further studies into a fundamental process that impacts plant growth and crop productivity.

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“…It was proposed that KNAT1 and ER are required to restrict the action of an asymmetrically localized, vasculature-associated chlorenchyma repressor at the nodes, and that ER functions redundantly with KNAT1 to influence plant architecture and stem differentiation (Douglas et al 2002). Although our previous results showed that ER plays an important role in leaf polarity formation, very little is known about the physiological function of ER in the AS1/AS2 regulatory pathway.…”

Section: Introductionmentioning

confidence: 97%

ERECTA is required for protection against heat-stress in the AS1 / AS2 pathway to regulate adaxial?abaxial leaf polarity in Arabidopsis

Sun

et al. 2004

Planta

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In seed plants, formation of the adaxial-abaxial polarity is of primary importance in leaf patterning. Since Arabidopsis thaliana (L.) Heynh. genes ASYMMETRIC LEAVES1 ( AS1) and ASYMMETRIC LEAVES2 ( AS2) are key regulators in specifying adaxial leaf identity, and ERECTA is involved in the AS1/ AS2 pathway for regulating adaxial-abaxial polarity [L. Xu et al. (2003) Development 130:4097-4107], we studied the physiological functions of the ERECTA protein in plant development. We analyzed the effects of different environmental conditions on a special leaf structure in the as1 and as2 mutants. This structure, called the lotus-leaf, reflects a severe loss of adaxial-abaxial polarity in leaves. Higher concentrations of salt or other osmotic substance and lower temperature severely affected plant growth both in the wild type and the mutants, but did not affect lotus-leaf frequency in the as1 and as2 mutants. as1 and as2 mutants exhibited a very low lotus-leaf frequency at 22 degrees C, a temperature that favors Arabidopsis growth. The lotus-leaf frequency rose significantly with an increase in growth temperature, and only in plants that are in the erecta mutation background. These results suggest that ERECTA function is required for reducing plant sensitivity to heat stress during adaxial-abaxial polarity formation in leaves.

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KNAT1 and ERECTA Regulate Inflorescence Architecture in Arabidopsis

Cited by 221 publications

References 34 publications

Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Genome-wide analysis of gene expression in soybean shoot apical meristem

ERECTA is required for protection against heat-stress in the AS1 / AS2 pathway to regulate adaxial?abaxial leaf polarity in Arabidopsis

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