MicroRNA–mediated repression of the seed maturation program during vegetative development in Arabidopsis

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DOIResolve DOI: http://doi.org/10.1371/journal.pgen.1003091
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TypeArticle
Journal titlePLoS Genetics
ISSN1553-7404
Volume8
Issue11
Pagese1003091:1e1003091:13; # of pages: 13
Subjectallele; Arabidopsis; argonaute 1 gene; article; bioaccumulation; controlled study; gene function; gene interaction; gene isolation; gene loss; gene overexpression; gene repression; genetic code; genetic screening; PHABULOSA gene; PHAVOLUTA gene; plant gene; plant leaf; reporter gene; seed development; transgenic plant; vegetative growth; argonaute 1 protein; microRNA; microRNA 166; small untranslated RNA; unclassified drug
AbstractThe 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.
Publication date
PublisherPLoS Genetics
LanguageEnglish
AffiliationNational Research Council Canada; NRC Plant Biotechnology Institute; Aquatic and Crop Resource Development
Peer reviewedYes
NRC number55450
NPARC number21268512
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Record identifierbd28cae2-0957-414a-ab27-ed4735783941
Record created2013-09-03
Record modified2016-05-09
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