Deficiens, a homeotic gene involved in the control of flower morphogenesis in Antirrhinum majus: the protein shows homology to transcription factors.

Sommer, Hans; Beltrán, José Pío; Huijser, Peter; Pape, Heike; Lönnig, Wolf-Ekkehard; Saedler, Heinz; Schwarz‐Sommer, Zsuzsanna

doi:10.1002/j.1460-2075.1990.tb08152.x

Cited by 715 publications

(482 citation statements)

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“…In Arabidopsis, at least five genes-APETALA1 (API), AP-ETALA2 (AP2), APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG)-are responsible for this determination (5,(8)(9)(10)(11). Several of these genes have now been cloned and found to be homologous to known transcription factors identified in yeast and mammals (12)(13)(14)(15). One of these genes, AG, important for carpel identity (5,8,16), is also potentially involved in ovule development.…”

Section: Introductionmentioning

confidence: 99%

Arabidopsis floral homeotic gene BELL (BEL1) controls ovule development through negative regulation of AGAMOUS gene (AG).

Ray

Robinson-Beers²,

Ray³

et al. 1994

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

121

104

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Ovules are the developmental precursors of seeds. In angiosperms the ovules are enclosed within the central floral organs, the carpels. We have identified a homeotic mutation in Arabidopsis, "bell" (bell), which causes transormation of ovule integuments into carpels. In situ hybridization analysis shows that this mutation leads to increased expression of the carpel-determining homeotic gene AGAMOUS (AG) A typical angiosperm flower includes four major organ types-sepals, petals, stamens, and carpels. The carpels include an additional set of distinct internal structures, the ovules. As the precursors of seeds, ovules play an essential role in higher plant sexual reproduction. Ovules are also found in gymnosperms, which lack carpels, and fossil evidence of angiosperm ancestors demonstrates that ovules precede the evolution of carpels (1-3). Thus, ovules evolved first, with subsequent evolution ofthe enclosing carpel. From this perspective, ovules can be viewed as separate floral organs, which, in angiosperms, develop from and are enclosed within the carpels.Little is known concerning the genetic control of determination and differentiation of ovules. This contrasts with recent progress in elucidation of control of development of other floral organs, where analysis offloral homeotic mutants in Arabidopsis thaliana and Antirrhinum majus has led to the formulation of two similar models for genetic determination of the identity of the four major floral organs (4-8). In Arabidopsis, at least five genes-APETALA1 (API), AP-ETALA2 (AP2), APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG)-are responsible for this determination (5,(8)(9)(10)(11). Several of these genes have now been cloned and found to be homologous to known transcription factors identified in yeast and mammals (12)(13)(14)(15). One of these genes, AG, important for carpel identity (5,8,16), is also potentially involved in ovule development. The expression ofAG occurs both early and late in flower development (16 (20). Mapping relative to RFLP (restriction fragment length polymorphism) (21) was performed on F2 progeny (96 chromosomes analyzed) from a bell-l/bell-l Ler x Co-3 cross. RFLP probes were M247 (Bgl II digestions) and g4028 (HindIII digestions). To determine the frequency ofintegument-to-carpel transformation in different alleles, ovules in >150 pistils from at least three different plants for each allele were scored for carpelloid features.Microscopy and in Situ Hybridization. Scanning electron microscopy was performed as described (17). In situ hybridization was carried out as described earlier (22 (16) were treated in the same experiment. Only exposures providing subsaturated grains were counted. For wild-type ovules, the area delimited by the endothelium and the embryo sac was not counted. The mean grain surface density (+SD) before background correction in the integument area on sections of wild-type ovules probed with anti-AG was 0.029 (±0.007) (10 ovules counted), and that for bell-i ovules with the same probe was 0.076 (+0.046) (13 ...

show abstract

Section: Introductionmentioning

confidence: 99%

Arabidopsis floral homeotic gene BELL (BEL1) controls ovule development through negative regulation of AGAMOUS gene (AG).

Ray

Robinson-Beers²,

Ray³

et al. 1994

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

121

104

View full text Add to dashboard Cite

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“…Using a parametric bootstrapping approach, were unable to reject a null hypothesis placing the duplication of DEF within Lamiales at the same relative position as for FLO (after divergence of the lineage leading to Veronicaceae) consistent with simultaneous duplication of both genes, possibly as a result of an ancient whole genome duplication event within Lamiales. Accordingly, we follow the nomenclature for these newly cloned DEF homologs as in that reflects the precedence of A. majus DEF (Sommer et al 1990), with co-orthologs further delineated as DEFA and DEFB ( Fig. 1; Supplementary Table S1).…”

Section: Lfy/flo-and Ap3/def-like Genes In Phrymaceaementioning

confidence: 99%

“…These include co-orthologs of the floral meristem identity gene FLO (Coen et al 1990) and floral homeotic MADS box gene DEF (Sommer et al 1990) from the model Lamiales species Antirrhinum majus. Orthologs of FLO and DEF from A. thaliana (LFY and AP3, respectively [Weigel et al 1992;Jack et al 1992]) carry out similar functions in the floral regulatory pathway as in A. majus, where LFY/FLO positively regulates the expression of the downstream gene AP3/DEF (Ingram et al 1997;Weigel and Meyerowitz 1993).…”

Section: Introductionmentioning

confidence: 99%

Relaxed Selection Among Duplicate Floral Regulatory Genes in Lamiales

2006

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Abstract. Polyploidization is a prevalent mode of genome diversification within plants. Most gene duplicates arising from polyploidization (paralogs) are typically lost, although a subset may be maintained under selection due to dosage, partitioning of gene function, or acquisition of novel functions. Because they experience selection in the presence of other duplicate loci across the genome, interactions among genes may also play a significant role in the maintenance of paralogs resulting from polyploidization. Previously, we identified duplicates of the genes LFY/FLO and AP3/DEF that directly interact in a floral regulatory pathway and are thought to be the result of ancient polyploidization in the Lamiales (> 50 mya). Although duplicates of MADS box genes including AP3/DEF are common throughout the angiosperm lineage, LFY/FLO duplicates in Lamiales are the first reported outside of tetraploid taxa. In order to explore hypotheses for the joint preservation of these interacting floral regulatory genes including novel LFY/FLO paralogs, here we clone FLO and DEF duplicates from additional Lamiales taxa and apply codon substitution models to test how selection acts on both genes following duplication. We find acceleration in the ratio of nonsynonymous-to-synonymous nucleotide substitutions for one (FLO) or both (DEF) paralogs that appears to be due to relaxed purifying selection as opposed to positive selection and shows a different pattern among functional domains of these genes. Several mechanisms are discussed that might be responsible for preservation of co-orthologs of FLO and DEF in Lamiales, including interactions among the genes of this regulatory pathway.

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“…def is required for stamen and petal identity and is expressed in these organ primordia (Sommer et al 1990). In the absence of rio, def expression was not detected, however, def expression was detected in all three layers of flo L1 and L3 periclinal chimeras.…”

Section: Fasciated (Fas) Tomato Mutants Have a Larger Meristemmentioning

confidence: 99%

“…Both def and globosa (glo) are required for the identity of floral organs in the second and third whorl floral organs; petals are replaced by sepals and stamens have carpel identity in def or glo mutant plants (Sommer et al 1990;Schwarz-Sommer et al 1992;Tr6bner et al 1992). glo and def are induced independently but require each other for upregulation; in the absence of one protein, the other protein is missing Tr6bner et al 1992).…”

Section: Do Transcription Factors Traffic Between Plant Cells?mentioning

confidence: 99%