epigenetic regulation of flower development in the oil palm
TRANSCRIPT
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Epigenetic regulation of flower Epigenetic regulation of flower
development in the oil palmdevelopment in the oil palm
Plant and Animal Genome XX
Palm Genomics and Genetics Workshop
January 15, 2012
Alain RIVAL, Thierry BEULE, Frédérique RICHAUD, Pascal ILBERT,
Estelle JALIGOT
CIRAD, UMR DIADE, Montpellier, France
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Why studying the oil palm at all?
• Because it is the 1 st world source of vegetable oil and consumption for foodand energy can only rise withincreasing population.increasing population.
• Because its mantled floral phenotypeprovide an original model where agro-economical interests fuel the search for basic knowledge in a tropical perennial.
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Characteristics of the mantled phenotype
• Somaclonal variation: arises from in vitro cloning• Alteration of floral organs: poor oil accumulation, infertility, visible in adult t rees only• Highly heterogeneous: frequency, severity, genotype e ffect• Unstable: spontaneous reversion
Normal fruit
Slightly mantled fruit
Severely mantled fruit
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Dealing with mantledness from
both ends of the cloning process
Somatic embryogenesis
• Working on adult palms to understand the molecular origin of the floral phenotype
• Working on in vitro cultures to test potential markers for early detection
Embryogenic cell culture Adult regenerant palm
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A few things we know about mantled
• No genetic/cytologic alteration• Non-mendelian inheritance• Hypomethylated genome
-19.3% -7.4%
• Altered gene transcription• Phenotype: stamen converted into carpels,
reminiscent of B-class MADS-box gene mutants
-19.3% -7.4%
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The hypothesis
• Epigenetic mechanisms regulating geneexpression are perturbated by the cloningprocess (hormones, re-programming)
• Most of these alterations have no detectable• Most of these alterations have no detectableimpact on the phenotype and/or subside
• The pathway governing floral organformation remains affected in the adult stage (sensitivity shared amongst Palms?)
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• In vitro material: investigating the genomic and epigenetic stability duringthe tissue culture process
The strategy
• Adult (inflorescence) material: exploring the epigenetic regulation of flower development
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• In vitro material: investigating the genomic and epigenetic stability duringthe tissue culture process
The strategy
Follow -up on the
• Adult (inflorescence) material: exploring the epigenetic regulation of flower development
Follow -up on the phenotypic stability
in the field
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• In vitro material: investigating the genomic and epigenetic stability duringthe tissue culture process
The strategy
Tracing back the origin
• Adult (inflorescence) material: exploring the epigenetic regulation of flower development
Tracing back the originof the mantled
phenotype
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Investigating the stability of cell cultures
Seed-derived palm
Normal
regenerant
Mantled
regenerant
Cloning 1
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Investigating the stability of cell cultures
Seed-derived palm
Normal
regenerant
Mantled
regenerant
Cloning 1
Propagation over 1 year, periodical samplings for DNA /RNA extractions
« Normal » cell lines « Mantled » cell lines
Cloning 2 Cloning 2
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Exploring the epigenetic
regulation of flower development
Floral MADS-box genes
Chanderbali et al., 2010
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Exploring the epigenetic
regulation of flower development
Floral MADS-box genes
Polycomb-group genes
Ele
men
ts
Chanderbali et al., 2010
Transcription factors
Tran
spos
able
E
lem
ents
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Exploring the epigenetic
regulation of flower development
Floral MADS-box genes
Polycomb-group genes
Ele
men
ts
Bisulfite, ChIP
Different epigenetic marks in mantled flowers?
RNAseq, Q-PCR
Chanderbali et al., 2010
Transcription factors
Tran
spos
able
E
lem
ents
Bisulfite, ChIP
Different mRNA/sRNA levelsin mantled flowers?
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« Things written in pen you can’t change. That’s DNA.But things written in pencil you can. That’s epigenetics »
Danielle Reed, geneticistNational Geographic, January 2012 issue
ThankThank youyou for for youryour attentionattention