BRANCHED SILKLESSmediates the transition from spikelet to floral meristem duringZea maysear development

Colombo, Lucia; Marziani, Giovanna; Masiero, Simona; Wittich, P.; Schmidt, Robert J.; Gorla, M. Sari; Pè, Mario Enrico

doi:10.1046/j.1365-313x.1998.00300.x

Cited by 44 publications

(30 citation statements)

References 32 publications

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“…bd1 mutants display an indeterminate SM in the tassel, whereas in the ear the SM look morphologically like BM (Chuck et al, 2002;Colombo et al, 1998). Double mutants between bd1 and tsh4 showed an additive phenotype in the tassel (Fig.…”

Section: Research Articlementioning

confidence: 92%

The maize SBP-box transcription factor encoded by tasselsheath4 regulates bract development and the establishment of meristem boundaries

et al. 2010

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Plant architecture consists of repeating units called phytomers, each containing an internode, leaf and axillary meristem. The formation of boundaries within the phytomer is necessary to differentiate and separate these three components, otherwise some will grow at the expense of others. The microRNA-targeted SBP-box transcription factor tasselsheath4 (tsh4) plays an essential role in establishing these boundaries within the inflorescence. tsh4 mutants display altered phyllotaxy, fewer lateral meristems and ectopic leaves that grow at the expense of the meristem. Double-mutant analyses of tsh4 and several highly branched mutants, such as ramosa1-3 and branched silkless1, demonstrated a requirement for tsh4 in branch meristem initiation and maintenance. TSH4 protein, however, was localized throughout the inflorescence stem and at the base of lateral meristems, but not within the meristem itself. Double labeling of TSH4 with the ramosa2, branched silkless1 and knotted1 meristem markers confirmed that TSH4 forms a boundary adjacent to all lateral meristems. Indeed, double labeling of miR156 showed a meristem-specific pattern complementary to that of TSH4, consistent with tsh4 being negatively regulated by this microRNA. Thus, downregulation of TSH4 by a combination of microRNAs and branching pathway genes allows the establishment of lateral meristems and the repression of leaf initiation, thereby playing a major role in defining meristem versus leaf boundaries.

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Section: Research Articlementioning

confidence: 92%

The maize SBP-box transcription factor encoded by tasselsheath4 regulates bract development and the establishment of meristem boundaries

et al. 2010

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“…We determined that the expression domain of FZP during the development of rice inflorescences was localized in the axils of rudimentary glume primordia of spikelet meristems, and that floral meristems were replaced by higher order branches composed of several rudimentary glumes in fzp mutant alleles. Similarly, the transcripts of the ortholog in maize, BD1, were found in a narrow region between the spikelet meristem and the glumes (Chuck et al, 2002), and bd1 spikelet meristems could not switch to floral meristem production, instead continuing to form glumes and spikeletlike meristems (Colombo et al, 1998). By comparison, we propose that the rudimentary glumes of rice are the equivalents of glumes of other grass species and, consequently, the empty glumes correspond to sterile lemmas and subtending florets might have been lost during the course of evolution as suggested by Arber (Arber, 1934).…”

Section: Rudimentary Glumes Are Actually Glumesmentioning

confidence: 99%

“…example, in the branched silkless1 (bd1) mutant, indeterminate branches are formed in the place of spikelets in the ear and extra spikelets are formed in the tassel (Colombo et al, 1998). Recently, the BD1 gene was reported to be a member of the ERF family of transcription factors, and it was proposed that signaling pathways involving BD1 regulate meristem identity from the lateral domains of spikelet meristems (Chuck et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

FRIZZY PANICLEis required to prevent the formation of axillary meristems and to establish floral meristem identity in rice spikelets

et al. 2003

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Inflorescences of grass species have a distinct morphology in which florets are grouped in compact branches called spikelets. Although many studies have shown that the molecular and genetic mechanisms that control floret organ formation are conserved between monocots and dicots, little is known about the genetic pathway leading to spikelet formation. In the frizzy panicle(fzp) mutant of rice, the formation of florets is replaced by sequential rounds of branching. Detailed analyses revealed that several rudimentary glumes are formed in each ectopic branch, indicating that meristems acquire spikelet identity. However, instead of proceeding to floret formation, axillary meristems are formed in the axils of rudimentary glumes and they either arrest or develop into branches of higher order. The fzp mutant phenotype suggests that FZP is required to prevent the formation of axillary meristems within the spikelet meristem and permit the subsequent establishment of floral meristem identity. The FZP gene was isolated by transposon tagging. FZP encodes an ERF transcription factor and is the rice ortholog of the maize BD1gene. Consistent with observations from phenotypic analyses, FZPexpression was found to be restricted to the time of rudimentary glumes differentiation in a half-ring domain at the base of which the rudimentary glume primordium emerged.

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“…The maize mutants ramosa1 (ra1), ra2, and ra3 change spikelet-pair meristems to branch meristems, resulting in more branches in the tassel and the development of branches in the ear (Vollbrecht et al, 2005;Bortiri et al, 2006;Satoh-Nagasawa et al, 2006). Likewise, mutants in the orthologous ethylene response factor (ERF) family of APETALA2 (AP2) transcription factor genes branched silkless1 (bd1) in maize and FRIZZY PANICLE (FZP) in rice result in highly ramified inflorescences due to conversion of spikelet meristems to branch meristems (Colombo et al, 1998;Chuck et al, 2002;Komatsu et al, 2003a;Zhu et al, 2003;Yi et al, 2005).…”

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confidence: 99%

MORE SPIKELETS1Is Required for Spikelet Fate in the Inflorescence of Brachypodium

Derbyshire

Byrne

2013

Plant Physiology

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Grasses produce florets on a structure called a spikelet, and variation in the number and arrangement of both branches and spikelets contributes to the great diversity of grass inflorescence architecture. In Brachypodium (Brachypodium distachyon), the inflorescence is an unbranched spike with a terminal spikelet and a limited number of lateral spikelets. Spikelets are indeterminate and give rise to a variable number of florets. Here, we provide a detailed description of the stages of inflorescence development in Brachypodium. To gain insight into the genetic regulation of Brachypodium inflorescence development, we generated fast neutron mutant populations and screened for phenotypic mutants. Among the mutants identified, the more spikelets1 (mos1) mutant had an increased number of axillary meristems produced from inflorescence meristem compared with the wild type. These axillary meristems developed as branches with production of higher order spikelets. Using a candidate gene approach, mos1 was found to have a genomic rearrangement disrupting the expression of an ethylene response factor class of APETALA2 transcription factor related to the spikelet meristem identity genes branched silkless1 (bd1) in maize (Zea mays) and FRIZZY PANICLE (FZP) in rice (Oryza sativa). We propose MOS1 likely corresponds to the Brachypodium bd1 and FZP ortholog and that the function of this gene in determining spikelet meristem fate is conserved with distantly related grass species. However, MOS1 also appears to be involved in the timing of initiation of the terminal spikelet. As such, MOS1 may regulate the transition to terminal spikelet development in other closely related and agriculturally important species, particularly wheat (Triticum aestivum).Plant shoots develop from the shoot apical meristem, which comprises a central region of pluripotent cells and a peripheral region where cells are recruited to form lateral organs. The shoot apical meristem is established early in embryogenesis and gives rise to all aerial portions of the plant. Following a reproductive transition, the shoot apical meristem converts to an inflorescence meristem, which may produce axillary meristems that form branches and flowers. The production, arrangement, and fate of meristems determine inflorescence architecture.Plant inflorescence architecture is vastly diverse, and one of the most dramatic reflections of this diversity is in the major cereal crop species. In maize (Zea mays), the tassel and ear inflorescence is indeterminate. Axillary meristems produced by the inflorescence in the tassel are initially indeterminate branches. Both the tassel and ear inflorescence, as well as branches of the tassel, produce spikelet pair meristems that then form determinate spikelet meristems, which terminate with production of two flowers or florets (Bortiri and Hake, 2007;Kellogg, 2007). In the rice (Oryza sativa) inflorescence or panicle, branch meristems initially produce secondary branch meristems. Both primary and secondary branches produce lateral spikelet meri...

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BRANCHED SILKLESSmediates the transition from spikelet to floral meristem duringZea maysear development

Cited by 44 publications

References 32 publications

The maize SBP-box transcription factor encoded by tasselsheath4 regulates bract development and the establishment of meristem boundaries

The maize SBP-box transcription factor encoded by tasselsheath4 regulates bract development and the establishment of meristem boundaries

FRIZZY PANICLEis required to prevent the formation of axillary meristems and to establish floral meristem identity in rice spikelets

MORE SPIKELETS1Is Required for Spikelet Fate in the Inflorescence of Brachypodium

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