The Plant Cell, Vol. 25: 4283, November 2013, www.plantcell.org ã 2013 American Society of Plant Biologists. All rights reserved.
IN BRIEF
Small RNAs and the Big Decisions: MicroRNA Regulation of Photoperiodic Flowering in Brachypodium distachyon Should I make flowers now, or wait and maybe develop a few more leaves? It’s a decision with important implications for reproductive success of wild plants and yields of domesticated plants. Plants can't call a friend to ask for advice on this big decision; instead, they rely on their ability to interpret signals from multiple sources (reviewed in Amasino, 2010). These inputs include endogenous and environmental cues: daylength, temperature, autonomous signals, hormones, and plant age. Signaling pathways integrate these inputs to regulate production of the floral initiator protein, termed florigen. Encoded by FLOWERING LOCUS T (F T) and F T orthologs and produced in the leaves, florigen translocates to the shoot apex to initiate flowering. Many studies have yielded a clear picture of how positive and negative factors integrate endogenous and environmental cues to control F T transcription, but the posttranscriptional regulation of F T, particularly in monocots, remains unclear. Here, Wu et al. (pages 4363–4377) examine the function of miR5200, a Brachypodium distachyon microRNA that targets the F T orthologs F TL1 and F TL2 and, like the F TLs, is expressed in leaves. miR5200 appears to specifically affect the response to photoperiod: miR5200 levels do not change in response to vernalization but are high under short-day and undetectably low under long-day conditions. Regulation of miR5200 involves increases in the repressive histone modification H3K27me3 at the loci encoding miR5200 in long-day conditions. Also, miR5200-overexpressing plants flower later under long-day conditions (see figure) and miR5200 target mimic plants, which express an uncleavable mRNA complementary to the microRNA, flower earlier under short-day conditions. Thus, miR5200 specifically represses F TL1
www.plantcell.org/cgi/doi/10.1105/tpc.113.251112
Overexpression of miR5200 delays flowering under long-day conditions. B. distachyon plants overexpressing miR5200 flower much later. Left, the wild-type plant at 2 months old; center and right, plants overexpressing miR5200 at 4 months old. White arrows indicate spikes. (Reprinted from Wu et al. [2013], Figure 2C.)
and F TL2 in short-day conditions, preventing flowering. Despite its key role, this microRNA has a very limited species distribution: The authors detected miR5200 only in Pooideae, including B.distachyon and barley (Hordeum vulgare), but not in other monocots or dicots. This limited distribution indicates both its likely recent evolution and its potential utility for breeding or transgenic manipulation of floral initiation in other crops. For example, regulation of flowering time figures into strategies for generating hybrids and restricting gene flow, and manipulation of the response to daylength enables breeders to extend the range where crops can be planted. Thus, this study may allow breeders to help plants
make that big decision and thereby improve important monocot crops.
Jennifer Mach Science Editor [email protected]
REFERENCES Amasino, R. (2010). Seasonal and developmental timing of flowering. Plant J. 61: 1001–1013. Wu, L., Liu, D., Wu, J., Zhang, R., Qin, Z., Liu, D., Li, A., Fu, D., Zhai, W., and Mao, L. (2013). Regulation of FLOWERING LOCUS T by a microRNA in Brachypodium distachyon. Plant Cell 25: 4363–4377.
Small RNAs and the Big Decisions: MicroRNA Regulation of Photoperiodic Flowering in Brachypodium distachyon Jennifer Mach Plant Cell 2013;25;4283; originally published online November 27, 2013; DOI 10.1105/tpc.113.251112 This information is current as of May 29, 2015 References
This article cites 2 articles, 1 of which can be accessed free at: http://www.plantcell.org/content/25/11/4283.full.html#ref-list-1
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IN BRIEF
Small RNAs and the Big Decisions: MicroRNA Regulation of Photoperiodic Flowering in Brachypodium distachyon Should I make flowers now, or wait and maybe develop a few more leaves? It’s a decision with important implications for reproductive success of wild plants and yields of domesticated plants. Plants can't call a friend to ask for advice on this big decision; instead, they rely on their ability to interpret signals from multiple sources (reviewed in Amasino, 2010). These inputs include endogenous and environmental cues: daylength, temperature, autonomous signals, hormones, and plant age. Signaling pathways integrate these inputs to regulate production of the floral initiator protein, termed florigen. Encoded by FLOWERING LOCUS T (F T) and F T orthologs and produced in the leaves, florigen translocates to the shoot apex to initiate flowering. Many studies have yielded a clear picture of how positive and negative factors integrate endogenous and environmental cues to control F T transcription, but the posttranscriptional regulation of F T, particularly in monocots, remains unclear. Here, Wu et al. (pages 4363–4377) examine the function of miR5200, a Brachypodium distachyon microRNA that targets the F T orthologs F TL1 and F TL2 and, like the F TLs, is expressed in leaves. miR5200 appears to specifically affect the response to photoperiod: miR5200 levels do not change in response to vernalization but are high under short-day and undetectably low under long-day conditions. Regulation of miR5200 involves increases in the repressive histone modification H3K27me3 at the loci encoding miR5200 in long-day conditions. Also, miR5200-overexpressing plants flower later under long-day conditions (see figure) and miR5200 target mimic plants, which express an uncleavable mRNA complementary to the microRNA, flower earlier under short-day conditions. Thus, miR5200 specifically represses F TL1
www.plantcell.org/cgi/doi/10.1105/tpc.113.251112
Overexpression of miR5200 delays flowering under long-day conditions. B. distachyon plants overexpressing miR5200 flower much later. Left, the wild-type plant at 2 months old; center and right, plants overexpressing miR5200 at 4 months old. White arrows indicate spikes. (Reprinted from Wu et al. [2013], Figure 2C.)
and F TL2 in short-day conditions, preventing flowering. Despite its key role, this microRNA has a very limited species distribution: The authors detected miR5200 only in Pooideae, including B.distachyon and barley (Hordeum vulgare), but not in other monocots or dicots. This limited distribution indicates both its likely recent evolution and its potential utility for breeding or transgenic manipulation of floral initiation in other crops. For example, regulation of flowering time figures into strategies for generating hybrids and restricting gene flow, and manipulation of the response to daylength enables breeders to extend the range where crops can be planted. Thus, this study may allow breeders to help plants
make that big decision and thereby improve important monocot crops.
Jennifer Mach Science Editor [email protected]
REFERENCES Amasino, R. (2010). Seasonal and developmental timing of flowering. Plant J. 61: 1001–1013. Wu, L., Liu, D., Wu, J., Zhang, R., Qin, Z., Liu, D., Li, A., Fu, D., Zhai, W., and Mao, L. (2013). Regulation of FLOWERING LOCUS T by a microRNA in Brachypodium distachyon. Plant Cell 25: 4363–4377.
Small RNAs and the Big Decisions: MicroRNA Regulation of Photoperiodic Flowering in Brachypodium distachyon Jennifer Mach Plant Cell 2013;25;4283; originally published online November 27, 2013; DOI 10.1105/tpc.113.251112 This information is current as of May 29, 2015 References
This article cites 2 articles, 1 of which can be accessed free at: http://www.plantcell.org/content/25/11/4283.full.html#ref-list-1
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https://www.copyright.com/ccc/openurl.do?sid=pd_hw1532298X&issn=1532298X&WT.mc_id=pd_hw1532298X
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© American Society of Plant Biologists ADVANCING THE SCIENCE OF PLANT BIOLOGY
