AGL24,SHORT VEGETATIVE PHASE, andAPETALA1Redundantly ControlAGAMOUSduring Early Stages of Flower Development inArabidopsis

Gregis, Veronica; Sessa, Alice; Colombo, Lucia; Kater, Martin M.

doi:10.1105/tpc.106.041798

Cited by 217 publications

(228 citation statements)

References 43 publications

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“…Indeed, recent studies have shown that most genes of this family are expressed in several plant tissues, organs, and developmental stages (Kofuji et al, 2003;Parenicová et al, 2003;Schmid et al, 2005). Other studies suggest that MADS-box functional specificity may depend on combinatorial protein-protein interactions (Egea-Cortines et al, 1999;Honma and Goto, 2001;de Folter et al, 2005;Kaufmann et al, 2005;Gregis et al, 2006;Sridhar et al, 2006), rather than on specific spatiotemporal expression patterns for each gene determined at the transcriptional level, as had been suggested before (Savidge et al, 1995;Alvarez-Buylla et al, 2000a).…”

Section: Discussionmentioning

confidence: 72%

AnAGAMOUS-Related MADS-Box Gene,XAL1(AGL12), Regulates Root Meristem Cell Proliferation and Flowering Transition in Arabidopsis

et al. 2008

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MADS-box genes are key components of the networks that control the transition to flowering and flower development, but their role in vegetative development is poorly understood. This article shows that the sister gene of the AGAMOUS (AG) clade, AGL12, has an important role in root development as well as in flowering transition. We isolated three mutant alleles for AGL12, which is renamed here as XAANTAL1 (XAL1): Two alleles, xal1-1 and xal1-2, are in Columbia ecotype and xal1-3 is in Landsberg erecta ecotype. All alleles have a short-root phenotype with a smaller meristem, lower rate of cell production, and abnormal root apical meristem organization. Interestingly, we also encountered a significantly longer cell cycle in the strongest xal1 alleles with respect to wild-type plants. Expression analyses confirmed the presence of XAL1 transcripts in roots, particularly in the phloem. Moreover, XAL1Tb-glucuronidase expression was specifically up-regulated by auxins in this tissue. In addition, mRNA in situ hybridization showed that XAL1 transcripts were also found in leaves and floral meristems of wildtype plants. This expression correlates with the late-flowering phenotypes of the xal1 mutants grown under long days. Transcript expression analysis suggests that XAL1 is an upstream regulator of SOC, FLOWERING LOCUS T, and LFY. We propose that XAL1 may have similar roles in both root and aerial meristems that could explain the xal1 late-flowering phenotype.

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Section: Discussionmentioning

confidence: 72%

AnAGAMOUS-Related MADS-Box Gene,XAL1(AGL12), Regulates Root Meristem Cell Proliferation and Flowering Transition in Arabidopsis

et al. 2008

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“…complex to repress AGAMOUS during floral development (Gregis et al, 2006). Similar interactions between SVP-like and AP1-like proteins may be important for floral development in cereals and other grasses.…”

Section: Discussionmentioning

confidence: 99%

Short Vegetative Phase-Like MADS-Box Genes Inhibit Floral Meristem Identity in Barley

Tadege²,

et al. 2006

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Analysis of the functions of Short Vegetative Phase (SVP)-like MADS-box genes in barley (Hordeum vulgare) indicated a role in determining meristem identity. Three SVP-like genes are expressed in vegetative tissues of barley: Barley MADS1 (BM1), BM10, and Vegetative to Reproductive Transition gene 2. These genes are induced by cold but are repressed during floral development. Ectopic expression of BM1 inhibited spike development and caused floral reversion in barley, with florets at the base of the spike replaced by tillers. Head emergence was delayed in plants that ectopically express BM1, primarily by delayed development after the floral transition, but expression levels of the barley VRN1 gene (HvVRN1) were not affected. Ectopic expression of BM10 inhibited spike development and caused partial floral reversion, where florets at the base of the spike were replaced by inflorescence-like structures, but did not affect heading date. Floral reversion occurred more frequently when BM1 and BM10 ectopic expression lines were grown in short-day conditions. BM1 and BM10 also inhibited floral development and caused floral reversion when expressed in Arabidopsis (Arabidopsis thaliana). We conclude that SVP-like genes function to suppress floral meristem identity in winter cereals.During the life cycle of a plant, the shoot apical meristem progresses through three phases of development: vegetative, inflorescence, and floral (Poethig, 1990). In each phase, the apical meristem produces a different set of organs. The vegetative meristem produces leaves, the inflorescence meristem produces leaves and floral meristems to form the inflorescence, and the floral meristem produces the organs that form the flower. The different phases of meristem development are controlled by genes that establish and maintain meristem identity.The shift from vegetative to inflorescence meristem identity, the floral transition, marks the beginning of the reproductive growth phase and is an important determinant of flowering time. In Arabidopsis (Arabidopsis thaliana), the Short Vegetative Phase (SVP) gene encodes a MADS-box transcription factor that delays the floral transition (Hartmann et al., 2000). Mutations that disrupt SVP cause early flowering (Hartmann et al., 2000), whereas ectopic expression of SVP results in late flowering. Ectopic expression of SVP also inhibits floral meristem identity, causing floral abnormalities such as the conversion of sepals and petals to leaf-like structures (Brill and Watson, 2004;Masiero et al., 2004) and causing inflorescence-like structures to develop within flowers (Brill and Watson, 2004). The development of inflorescences within flowers indicates that meristematic cells within the flower have lost floral identity and have formed an inflorescence instead of floral organs, a phenomenon known as floral reversion (Tooke et al., 2005). Presumably, ectopic expression of SVP causes floral reversion by interfering with a mechanism that maintains floral meristem identity.The Arabidopsis gene, AGAMOUS-LIKE 24 (AGL24)...

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“…This peculiar arrangement of BPC and MADS domain binding sites suggests that these factors might interact to facilitate binding to this promoter region. To investigate this further, we tested by yeast two-, three-, and four-hybrid experiments whether BPC proteins were able to interact with the AP1-SVP-SEU-LUG corepressor complex (Gregis et al, 2006). First, we tested by yeast two-hybrid assays the interactions between BPC1, BPC2, and BPC3, all cloned as BD fusions, with AP1, LUG, SEU, and SVP, all cloned as AD fusions.…”

Section: Bpc Factors Facilitate the Binding Of The Ap1-svp-seu-lug Rementioning

confidence: 99%

“…This complex is important to repress homeotic gene expression during the first stages of flower development to prevent precocious differentiation of the floral meristem into floral organs. For instance, it was shown that SVP and AP1 directly bind and repress MADS box floral organ identity genes, such as APE-TALA3 (AP3), PISTILLATA (PI), SEPALLATA3 (SEP3), and AG-AMOUS (AG) (Gregis et al, 2006;Gregis et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

“…During reproductive growth, SVP is expressed only in the floral meristem (stage 1 and 2 of flower development), which during this phase increases in size. In the floral meristem, SVP interacts with AP1 to recruit the LEUNIG (LUG)-SEUSS (SEU) corepressor (Gregis et al, 2006(Gregis et al, , 2009). This complex is important to repress homeotic gene expression during the first stages of flower development to prevent precocious differentiation of the floral meristem into floral organs.…”

Section: Introductionmentioning

confidence: 99%

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BASIC PENTACYSTEINE Proteins Mediate MADS Domain Complex Binding to the DNA for Tissue-Specific Expression of Target Genes in Arabidopsis

et al. 2012

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BASIC PENTACYSTEINE (BPC) transcription factors have been identified in a large variety of plant species. In Arabidopsis thaliana there are seven BPC genes, which, except for BPC5, are expressed ubiquitously. BPC genes are functionally redundant in a wide range of developmental processes. Recently, we reported that BPC1 binds to guanine and adenine (GA)-rich consensus sequences in the SEEDSTICK (STK) promoter in vitro and induces conformational changes. Here we show by chromatin immunoprecipitation experiments that in vivo BPCs also bind to the consensus boxes, and when these were mutated, expression from the STK promoter was derepressed, resulting in ectopic expression in the inflorescence. We also reveal that SHORT VEGETATIVE PHASE (SVP) is a direct regulator of STK. SVP is a floral meristem identity gene belonging to the MADS box gene family. The SVP-APETALA1 (AP1) dimer recruits the SEUSS (SEU)-LEUNIG (LUG) transcriptional cosuppressor to repress floral homeotic gene expression in the floral meristem. Interestingly, we found that GA consensus sequences in the STK promoter to which BPCs bind are essential for recruitment of the corepressor complex to this promoter. Our data suggest that we have identified a new regulatory mechanism controlling plant gene expression that is probably generally used, when considering BPCs' wide expression profile and the frequent presence of consensus binding sites in plant promoters.

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AGL24,SHORT VEGETATIVE PHASE, andAPETALA1Redundantly ControlAGAMOUSduring Early Stages of Flower Development inArabidopsis

Cited by 217 publications

References 43 publications

AnAGAMOUS-Related MADS-Box Gene,XAL1(AGL12), Regulates Root Meristem Cell Proliferation and Flowering Transition in Arabidopsis

AnAGAMOUS-Related MADS-Box Gene,XAL1(AGL12), Regulates Root Meristem Cell Proliferation and Flowering Transition in Arabidopsis

Short Vegetative Phase-Like MADS-Box Genes Inhibit Floral Meristem Identity in Barley

BASIC PENTACYSTEINE Proteins Mediate MADS Domain Complex Binding to the DNA for Tissue-Specific Expression of Target Genes in Arabidopsis

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