Abstract
The seed maturation program only occurs during late embryogenesis, and repression of the program is pivotal for seedling development. However, the mechanism through which this repression is achieved in vegetative tissues is poorly understood. Here we report a microRNA (miRNA)-mediated repression mechanism operating in leaves. To understand the repression of the embryonic program in seedlings, we have conducted a genetic screen using a seed maturation gene reporter transgenic line in Arabidopsis (Arabidopsis thaliana) for the isolation of mutants that ectopically express seed maturation genes in leaves. One of the mutants identified from the screen is a weak allele of ARGONAUTE1 (AGO1) that encodes an effector protein for small RNAs. We first show that it is the defect in the accumulation of miRNAs rather than other small RNAs that causes the ectopic seed gene expression in ago1. We then demonstrate that overexpression of miR166 suppresses the derepression of the seed gene reporter in ago1 and that, conversely, the specific loss of miR166 causes ectopic expression of seed maturation genes. Further, we show that ectopic expression of miR166 targets, type III homeodomain-leucine zipper (HD-ZIPIII) genes PHABULOSA (PHB) and PHAVOLUTA (PHV), is sufficient to activate seed maturation genes in vegetative tissues. Lastly, we show that PHB binds the promoter of LEAFY COTYLEDON2 (LEC2), which encodes a master regulator of seed maturation. Therefore, this study establishes a core module composed of a miRNA, its target genes (PHB and PHV), and the direct target of PHB (LEC2) as an underlying mechanism that keeps the seed maturation program off during vegetative development.
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Claims 6
Claim · model-written summary
A weak ARGONAUTE1 allele was identified among mutants expressing seed maturation genes ectopically in leaves.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae1 - Material
- weak allele of ARGONAUTE1 (AGO1)e0
- Gene
- ARGONAUTE1 (AGO1)e0
- Outcome
- ectopically express seed maturation genes in leavese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“One of the mutants identified from the screen is a weak allele of ARGONAUTE1 (AGO1) that encodes an effector protein for small RNAs.”
e1“in Arabidopsis (Arabidopsis thaliana) for the isolation of mutants that ectopically express seed maturation genes in leaves.”
Claim · model-written summary
Defective microRNA accumulation caused ectopic seed gene expression in ago1.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Material
- ago1e0
- Gene
- miRNAse0
- Outcome
- ectopic seed gene expressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it is the defect in the accumulation of miRNAs rather than other small RNAs that causes the ectopic seed gene expression in ago1.”
e1“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Overexpression of miR166 suppressed derepression of the seed gene reporter in ago1.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- overexpression of miR166e0
- Gene
- miR166e0
- Outcome
- derepression of the seed gene reportere0
- Direction
- suppressese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overexpression of miR166 suppresses the derepression of the seed gene reporter in ago1”
e1“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Specific loss of miR166 caused ectopic expression of seed maturation genes.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- specific loss of miR166e0
- Gene
- miR166e0
- Outcome
- ectopic expression of seed maturation genese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the specific loss of miR166 causes ectopic expression of seed maturation genes.”
e1“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Ectopic PHB and PHV expression activated seed maturation genes in vegetative tissues.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- ectopic expression of miR166 targetse0
- Gene
- PHABULOSA (PHB) and PHAVOLUTA (PHV)e0
- Outcome
- seed maturation genes in vegetative tissuese0
- Direction
- activatee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ectopic expression of miR166 targets, type III homeodomain-leucine zipper (HD-ZIPIII) genes PHABULOSA (PHB) and PHAVOLUTA (PHV), is sufficient to activate seed maturation genes in vegetative tissues.”
e1“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
PHB bound the LEC2 promoter.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- PHBe0
- Outcome
- binds the promoter of LEAFY COTYLEDON2 (LEC2)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PHB binds the promoter of LEAFY COTYLEDON2 (LEC2)”
e1“Arabidopsis (Arabidopsis thaliana)”
The same questions in other papers
overexpression · molecular: expression · Arabidopsis thaliana (thale cress)Positive and negative results
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