Molecular and Genetic Mechanisms of Floral Control

Jack, Thomas

doi:10.1105/tpc.017038

Cited by 382 publications

(290 citation statements)

References 185 publications

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“…It was recently demonstrated that vernalization requires epigenetic silencing of FLC by histone methylation and acetylation in specific regions of intron 1 Bastow et al 2004). This chromatin remodeling in intron 1 results in permanent suppression of FLC, which allows the expression of the genes SOC1, LFY and AP1, thus inducing flowering (Jack 2004).…”

Section: Intronic Regulatory Elementsmentioning

confidence: 99%

Large deletions within the first intron in VRN-1 are associated with spring growth habit in barley and wheat

et al. 2005

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The broad adaptability of wheat and barley is in part attributable to their flexible growth habit, in that spring forms have recurrently evolved from the ancestral winter growth habit. In diploid wheat and barley growth habit is determined by allelic variation at the VRN-1 and/or VRN-2 loci, whereas in the polyploid wheat species it is determined primarily by allelic variation at VRN-1. Dominant Vrn-A1 alleles for spring growth habit are frequently associated with mutations in the promoter region in diploid wheat and in the A genome of common wheat. However, several dominant Vrn-A1, Vrn-B1, Vrn-D1 (common wheat) and Vrn-H1 (barley) alleles show no polymorphisms in the promoter region relative to their respective recessive alleles. In this study, we sequenced the complete VRN-1 gene from these accessions and found that all of them have large deletions within the first intron, which overlap in a 4-kb region. Furthermore, a 2.8-kb segment within the 4-kb region showed high sequence conservation among the different recessive alleles. PCR markers for these deletions showed that similar deletions were present in all the accessions with known Vrn-B1 and Vrn-D1 alleles, and in 51 hexaploid spring wheat accessions previously shown to have no polymorphisms in the VRN-A1 promoter region. Twenty-four tetraploid wheat accessions had a similar deletion in VRN-A1 intron 1. We hypothesize that the 2.8-kb conserved region includes regulatory elements important for the vernalization requirement. Epistatic interactions between VRN-H2 and the VRN-H1 allele with the intron 1 deletion suggest that the deleted region may include a recognition site for the flowering repression mediated by the product of the VRN-H2 gene of barley.

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Section: Intronic Regulatory Elementsmentioning

confidence: 99%

Large deletions within the first intron in VRN-1 are associated with spring growth habit in barley and wheat

et al. 2005

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“…The Arabidopsis flower consists of four sepals, four petals, six stamens and two fused carpels from the outer to inner whorls. Floral organ identities are specified by transcription factors encoded by 3 classes of floral homeotic genes: the A, B and C function genes (Coen and Meyerowitz 1991;Meyerowitz et al 1991;reviewed in Gutierrez-Cortines and Davies 2000;Lohmann and Weigel 2002;Jack 2004;Krizek and Fletcher 2005). Class A genes specify sepals and interact with B genes to specify petals; C function genes specify carpels and interact with B function genes to specify stamens.…”

Section: Introductionmentioning

confidence: 99%

Floral patterning defects induced by Arabidopsis APETALA2 and microRNA172 expression in Nicotiana benthamiana

et al. 2006

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Floral patterning and morphogenesis are controlled by many transcription factors including floral homeotic proteins, by which floral organ identity is determined. Recent studies have uncovered widespread regulation of transcription factors by microRNAs (miRNAs), ~21-nucleotide noncoding RNAs that regulate protein-coding RNAs through transcript cleavage and/or translational inhibition. The regulation of the floral homeotic gene APETALA2 (AP2) by miR172 is crucial for normal Arabidopsis flower development and is likely to be conserved across plant species. Here we probe the activity of the AP2/miR172 regulatory circuit in a heterologous Solanaceae species, Nicotiana benthamiana. We generated transgenic N. benthamiana lines expressing Arabidopsis wild type AP2 (35S∷AP2), miR172-resistant AP2 mutant (35S∷AP2m3) and MIR172a-1 (35S∷MIR172) under the control of the cauliflower mosaic virus 35S promoter. 35S∷AP2m3 plants accumulated high levels of AP2 mRNA and protein and exhibited floral patterning defects that included proliferation of numerous petals, stamens and carpels indicating loss of floral determinacy. On the other hand, nearly all 35S∷AP2 plants accumulated barely detectable levels of AP2 mRNA or protein and were essentially non-phenotypic. Overall, the data indicated that expression of the wild type Arabidopsis AP2 transgene was repressed at the mRNA level by an endogenous N. benthamiana miR172 homologue that could be detected using Arabidopsis miR172 probe. Interestingly, 35S∷MIR172 plants had sepal-to-petal transformations and/or more sepals and petals, suggesting interference with N. benthamiana normal floral homeotic gene function in perianth organs. Our studies uncover the potential utility of the Arabidopsis AP2/miR172 system as a tool for manipulation of floral architecture and flowering time in non-model plants.

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“…Flower development has been the subject of intensive study over the last decade, particularly in two dicot species, Arabidopsis thaliana and Antirrhinum majus (Jack, 2004). These studies have provided a general understanding of the development of floral organs in higher plants and led to the production of the ABCDE model.…”

Section: Introductionmentioning

confidence: 99%

Genetic and Epigenetic Alteration among Three Homoeologous Genes of a Class E MADS Box Gene in Hexaploid Wheat

et al. 2007

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Bread wheat (Triticum aestivum) is a hexaploid species with A, B, and D ancestral genomes. Most bread wheat genes are present in the genome as triplicated homoeologous genes (homoeologs) derived from the ancestral species. Here, we report that both genetic and epigenetic alterations have occurred in the homoeologs of a wheat class E MADS box gene. Two class E genes are identified in wheat, wheat SEPALLATA (WSEP) and wheat LEAFY HULL STERILE1 (WLHS1), which are homologs of Os MADS45 and Os MADS1 in rice (Oryza sativa), respectively. The three wheat homoeologs of WSEP showed similar genomic structures and expression profiles. By contrast, the three homoeologs of WLHS1 showed genetic and epigenetic alterations. The A genome WLHS1 homoeolog (WLHS1-A) had a structural alteration that contained a large novel sequence in place of the K domain sequence. A yeast two-hybrid analysis and a transgenic experiment indicated that the WLHS1-A protein had no apparent function. The B and D genome homoeologs, WLHS1-B and WLHS1-D, respectively, had an intact MADS box gene structure, but WLHS1-B was predominantly silenced by cytosine methylation. Consequently, of the three WLHS1 homoeologs, only WLHS1-D functions in hexaploid wheat. This is a situation where three homoeologs are differentially regulated by genetic and epigenetic mechanisms.

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Molecular and Genetic Mechanisms of Floral Control

Cited by 382 publications

References 185 publications

Large deletions within the first intron in VRN-1 are associated with spring growth habit in barley and wheat

Large deletions within the first intron in VRN-1 are associated with spring growth habit in barley and wheat

Floral patterning defects induced by Arabidopsis APETALA2 and microRNA172 expression in Nicotiana benthamiana

Genetic and Epigenetic Alteration among Three Homoeologous Genes of a Class E MADS Box Gene in Hexaploid Wheat

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