AINTEGUMENTA and AINTEGUMENTA-LIKE6/PLETHORA3 Induce <i>LEAFY</i> Expression in Response to Auxin to Promote the Onset of Flower Formation in Arabidopsis

Yamaguchi, Nobutoshi; Jeong, Cheol Woong; Nole-Wilson, Staci; Krizek, Beth A.; Wagner, Doris

doi:10.1104/pp.15.00969

Cited by 75 publications

(70 citation statements)

References 57 publications

(123 reference statements)

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“…Interestingly, actinorhizal nodules, which are evolutionarily more ancient than legume nodules, feature a central vasculature (Péret et al, 2007). Furthermore, knockdown of several M. truncatula PLETHORA family members, encoding transcription factors that have been linked to auxin biosynthesis in Arabidopsis (Aida et al, 2004;Pinon et al, 2013;Yamaguchi et al, 2016), reduced nodulation and impaired nodule-meristem function in M. truncatula (Franssen et al, 2015). Based on these observations we can predict further overlap in the genes involved in the formation of nodules and lateral roots, but that different timing, levels, and location of expression of these genes will be important in determining which lateral organ is formed.…”

Section: Introductionmentioning

confidence: 99%

MtLAX2, a Functional Homologue of the Arabidopsis Auxin Influx Transporter AUX1, Is Required for Nodule Organogenesis

Roy

Robson²,

Lilley³

et al. 2017

Plant Physiol.

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Most legume plants can form nodules, specialized lateral organs that form on roots, and house nitrogen-fixing bacteria collectively called rhizobia. The uptake of the phytohormone auxin into cells is known to be crucial for development of lateral roots. To test the role of auxin influx in nodulation we used the auxin influx inhibitors 1-naphthoxyacetic acid (1-NOA) and 2-NOA, which we found reduced nodulation of Medicago truncatula. This suggested the possible involvement of the AUX/LAX family of auxin influx transporters in nodulation. Gene expression studies identified MtLAX2, a paralogue of Arabidopsis (Arabidopsis thaliana) AUX1, as being induced at early stages of nodule development. MtLAX2 is expressed in nodule primordia, the vasculature of developing nodules, and at the apex of mature nodules. The MtLAX2 promoter contains several auxin response elements, and treatment with indole-acetic acid strongly induces MtLAX2 expression in roots. mtlax2 mutants displayed root phenotypes similar to Arabidopsis aux1 mutants, including altered root gravitropism, fewer lateral roots, shorter root hairs, and auxin resistance. In addition, the activity of the synthetic DR5-GUS auxin reporter was strongly reduced in mtlax2 roots. Following inoculation with rhizobia, mtlax2 roots developed fewer nodules, had decreased DR5-GUS activity associated with infection sites, and had decreased expression of the early auxin responsive gene ARF16a. Our data indicate that MtLAX2 is a functional analog of Arabidopsis AUX1 and is required for the accumulation of auxin during nodule formation in tissues underlying sites of rhizobial infection.

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Section: Introductionmentioning

confidence: 99%

MtLAX2, a Functional Homologue of the Arabidopsis Auxin Influx Transporter AUX1, Is Required for Nodule Organogenesis

Roy

Robson²,

Lilley³

et al. 2017

Plant Physiol.

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“…5) shows that in addition to the transcriptional activation of individual lateral organ markers, entire regulatory gene modules are coordinately upregulated in DRNL::GFP + cells. One well-characterised GRN associated with lateral organ initiation at the IM periphery involves LFY , ANT , AIL6 and FIL downstream of MP [16, 39], and the subsequent upregulation of LMI1 , LMI2 , TLP8 and RAX1 by LFY [40–43]. The upregulation of these nine genes in the LOFC transcriptome confirms that this genetic interaction module contributes to the earliest stage of primordia anlagen.…”

Section: Discussionmentioning

confidence: 93%

The founder-cell transcriptome in the Arabidopsis apetala1 cauliflower inflorescence meristem

et al. 2016

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BackgroundAlthough the pattern of lateral organ formation from apical meristems establishes species-specific plant architecture, the positional information that confers cell fate to cells as they transit to the meristem flanks where they differentiate, remains largely unknown. We have combined fluorescence-activated cell sorting and RNA-seq to characterise the cell-type-specific transcriptome at the earliest developmental time-point of lateral organ formation using DORNRÖSCHEN-LIKE::GFP to mark founder-cell populations at the periphery of the inflorescence meristem (IM) in apetala1 cauliflower double mutants, which overproliferate IMs.ResultsWithin the lateral organ founder-cell population at the inflorescence meristem, floral primordium identity genes are upregulated and stem-cell identity markers are downregulated. Additional differentially expressed transcripts are involved in polarity generation and boundary formation, and in epigenetic and post-translational changes. However, only subtle transcriptional reprogramming within the global auxin network was observed.ConclusionsThe transcriptional network of differentially expressed genes supports the hypothesis that lateral organ founder-cell specification involves the creation of polarity from the centre to the periphery of the IM and the establishment of a boundary from surrounding cells, consistent with bract initiation. However, contrary to the established paradigm that sites of auxin response maxima pre-pattern lateral organ initiation in the IM, auxin response might play a minor role in the earliest stages of lateral floral initiation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3189-x) contains supplementary material, which is available to authorized users.

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“…6). Its closest Arabidopsis ortholog is ANT, which plays important roles in floral meristems, organ patterning, and particularly ovule and gametophyte development (Krizek, 2009;Klucher et al, 1996;Yamaguchi et al, 2016). Moreover, Arabidopsis SEP3 also directly influences ANT expression in differentiating Arabidopsis floral organs (Pajoro et al, 2014b).…”

Section: Discussionmentioning

confidence: 99%

Genome-Wide Targets Regulated by the OsMADS1 Transcription Factor Reveals Its DNA Recognition Properties

Khanday

Das²,

Chongloi³

et al. 2016

Plant Physiol.

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ORCID IDs: 0000-0003-4218-0559 (M.B.); 0000-0002-0522-8974 (U.G.).OsMADS1 controls rice (Oryza sativa) floral fate and organ development. Yet, its genome-wide targets and the mechanisms underlying its role as a transcription regulator controlling developmental gene expression are unknown. We identify 3112 geneassociated OsMADS1-bound sites in the floret genome. These occur in the vicinity of transcription start sites, within gene bodies, and in intergenic regions. Majority of the bound DNA contained CArG motif variants or, in several cases, only A-tracts. Sequences flanking the binding peak had a higher AT nucleotide content, implying that broader DNA structural features may define in planta binding. Sequences for binding by other transcription factor families like MYC, AP2/ERF, bZIP, etc. are enriched in OsMADS1-bound DNAs. Target genes implicated in transcription, chromatin remodeling, cellular processes, and hormone metabolism were enriched. Combining expression data from OsMADS1 knockdown florets with these DNA binding data, a snapshot of a gene regulatory network was deduced where targets, such as AP2/ERF and bHLH transcription factors and chromatin remodelers form nodes. We show that the expression status of these nodal factors can be altered by inducing the OsMADS1-GR fusion protein and present a model for a regulatory cascade where the direct targets of OsMADS1, OsbHLH108/ SPT, OsERF034, and OsHSF24, in turn control genes such as OsMADS32 and OsYABBY5. This cascade, with other similar relationships, cumulatively contributes to floral organ development. Overall, OsMADS1 binds to several regulatory genes and, probably in combination with other factors, controls a gene regulatory network that ensures rice floret development.

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AINTEGUMENTA and AINTEGUMENTA-LIKE6/PLETHORA3 Induce LEAFY Expression in Response to Auxin to Promote the Onset of Flower Formation in Arabidopsis

Cited by 75 publications

References 57 publications

MtLAX2, a Functional Homologue of the Arabidopsis Auxin Influx Transporter AUX1, Is Required for Nodule Organogenesis

MtLAX2, a Functional Homologue of the Arabidopsis Auxin Influx Transporter AUX1, Is Required for Nodule Organogenesis

The founder-cell transcriptome in the Arabidopsis apetala1 cauliflower inflorescence meristem

Genome-Wide Targets Regulated by the OsMADS1 Transcription Factor Reveals Its DNA Recognition Properties

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