Photo and hormonal control of meristem identity in the Arabidopsis flower mutants apetala2 and apetala1.

Okamuro, Jack K.; Szeto, Wayne; Lotys-Prass, Cynthia; Jofuku, K. Diane

doi:10.1105/tpc.9.1.37

Cited by 67 publications

(23 citation statements)

References 43 publications

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“…Together, these results indicate that AP2 does not directly specify perianth fate and appears not to fit its original A-function designation. This is in agreement with other reports suggesting that the disruption of perianth identity in ap2 mutants is an indirect effect reflecting an earlier role for AP2 in floral meristem specification (Okamuro et al, 1997;Litt, 2007;Causier et al, 2010). In this context, AP2 first contributes to floral meristem identity (required for the production of the perianth) and later regulates the expression domains of B-, C-and E-class genes that specify floral organ fate.…”

Section: Research Articlesupporting

confidence: 81%

APETALA2 negatively regulates multiple floral organ identity genes inArabidopsisby recruiting the co-repressor TOPLESS and the histone deacetylase HDA19

2012

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SUMMARYThe development and coordination of complex tissues in eukaryotes requires precise spatial control of fate-specifying genes. Although investigations of such control have traditionally focused on mechanisms of transcriptional activation, transcriptional repression has emerged as being equally important in the establishment of gene expression territories. In the angiosperm flower, specification of lateral organ fate relies on the spatial regulation of the ABC floral organ identity genes. Our understanding of how the boundaries of these expression domains are controlled is not complete. Here, we report that the A-class organ identity gene APETALA2 (AP2), which is known to repress the C-class gene AGAMOUS, also regulates the expression borders of the B-class genes APETALA3 and PISTILLATA, and the E-class gene SEPALLATA3. We show that AP2 represses its target genes by physically recruiting the co-repressor TOPLESS and the histone deacetylase HDA19. These results demonstrate that AP2 plays a broad role in flower development by controlling the expression domains of numerous floral organ identity genes.

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Section: Research Articlesupporting

confidence: 81%

APETALA2 negatively regulates multiple floral organ identity genes inArabidopsisby recruiting the co-repressor TOPLESS and the histone deacetylase HDA19

2012

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“…Floral reversion is also caused by mutations that inhibit floral meristem identity, such as ap1 (for review, see Tooke et al, 2005). In the ap1 mutant, floral reversion occurs more frequently in shortday conditions (Okamuro et al, 1997). In barley, we found that short-day conditions increased the frequency and severity of floral reversion in plants that ectopically express BM1 or BM10.…”

Section: Discussionmentioning

confidence: 49%

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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“…Several hormones were found to influence the expression of MADS box genes. These include gibberellins that control meristem identity in the Arabidopsis flower mutants apetala2 and apetala1, and cytokinin or gibberellins that induce flower formation by activating SaMADSA in Sinapis (Okamuro et al, 1997;Bonhomme et al, 2000). In oil palm, a correlation was found between lowered endogenous cytokinin levels in in vitro cultured plants and the appearance of abnormal inflorescences at a later stage (Duval et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

Characterization of oil palm MADS box genes in relation to the mantled flower abnormality

Alwee

Linden²,

Schoot³

et al. 2006

Plant Cell Tiss Organ Cult

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In vitro propagation of oil palm (Elaeis guineensis Jacq.) frequently induces a somaclonal variant called 'mantled' abnormality, in which the stamens of both male and female flowers are transformed into carpels. This leads to a reduced yield or complete loss of the harvest of palm oil. The high frequency of the abnormality in independent lines and the high reversal rate suggest that it is due to an epigenetic change. The type of morphological changes suggest that it involves homeotic MADS box genes that regulate the identity of the flower whorls. We have isolated a number of MADS box genes from oil palm inflorescences by a MADS box-directed mRNA display approach. The isolated partial cDNAs included genes that were likely to function at the initial stages of flowering as well as genes that may function in determination of the inflorescence and the identity of the flower whorls. For four genes that were homologous to genes known to affect the reproductive parts of the flower, full length cDNAs were isolated. These were a B-type MADS box gene which may function in the determination of stamen formation, a C-type gene expected to be involved in stamen and carpel formation, and two putative SEP genes which act in concert with the A-, Band C-type MADS box gene in determining flower whorl formation. The B-type gene EgMADS16 was functionally characterized as a PISTILLATA orthologue; it was able to complement an Arabidopsis thaliana pi mutant. Whether EgMADS16, or any of the other EgMADS genes, are functionally involved in the mantled condition remains to be established.

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Photo and hormonal control of meristem identity in the Arabidopsis flower mutants apetala2 and apetala1.

Cited by 67 publications

References 43 publications

APETALA2 negatively regulates multiple floral organ identity genes inArabidopsisby recruiting the co-repressor TOPLESS and the histone deacetylase HDA19

APETALA2 negatively regulates multiple floral organ identity genes inArabidopsisby recruiting the co-repressor TOPLESS and the histone deacetylase HDA19

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

Characterization of oil palm MADS box genes in relation to the mantled flower abnormality

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