The <i>forever young</i> gene encodes an oxidoreductase required for proper development of the <i>Arabidopsis</i> vegetative shoot apex

Callos, Joseph D.; Dirado, M.; Xu, Bing; Behringer, Friedrich J.; Link, Bruce M.; Medford, June I.

doi:10.1046/j.1365-313x.1994.6060835.x

Cited by 29 publications

(14 citation statements)

References 36 publications

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“…Alternatively, we may be lacking an essential regulatory element in the genomic fragment used for complementation (Figure 6), although this would suggest a lengthy promoter region because 4 kb upstream of the transcription start site was included. Partia1 complementation of an Arabidopsis mutant has been reported previously (Callos et al, 1994).…”

Section: Ant Has a Role In Floral Organ Developmentmentioning

confidence: 93%

The AINTEGUMENTA gene of Arabidopsis required for ovule and female gametophyte development is related to the floral homeotic gene APETALA2.

et al. 1996

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Ovules play a central role in plant reproduction, generating the female gametophyte within sporophytic integuments.When fertilized, the integuments differentiate into the seed coat and support the development of the embryo and endosperm. Mutations in the AlNTEGUMENTA (ANT) locus of Arabidopsis have a profound effect on ovule development. Strong ant mutants have ovules that fail to form integuments or a female gametophyte. Flower development is also altered, with a random reduction of organs in the outer three whorls. In addition, organs present in the outer three floral whorls often have abnormal morphology. Ovules from a weak ant mutant contain both inner and outer integuments but generally fail to produce a functional female gametophyte. We isolated the A N T gene by using a mutation derived by T-DNA insertional mutagenesis. A N T is a member of a gene family that includes the floral homeotic gene APETALA2 (AP2). Like AP2, ANT contains two AP2 domains homologous with the DNA binding domain of ethylene response element binding proteins. A N T is expressed most highly in developing flowers but is also expressed in vegetative tissue.Taken together, these results suggest that ANT is a transcription factor that plays a critical role in regulating ovule and female gametophyte development. I NTRODU CTI ONA unique element of plant reproduction is the alternation of generations between a diploid sporophyte and a haploid gametophyte. Ovules are fundamentally involved in this aspect of the plant life cycle due to their role in generating the female gametophyte or embryo sac. Ovule development has been proposed to occur in four distinct phases . The first phase involves the initiation of the ovule primordia from the carpel placenta. During the second phase, the specification of ovule identity occurs. This is followed by the formation of spatially defined pattern elements within the developing ovule in the third phase. The final phase involves morphogenesis to form the mature ovule. In angiosperms, morphogenesis results in ovules that consist of a nucellus enclosed by one or two integuments and a supporting stalk, the funicuIus, which attachcs the ovule to the placenta (Bouman, 1984;Reiser and Fischer, 1993). The megasporocyte is produced within the nucellus and undergoes meiosis to produce four megaspores (megasporogenesis). A single surviving megaspore will undergo megagametogenesis to produce the female gametophyte (Willemse and Van Went, 1984;Mansfield et al., 1990;Reiser and Fischer, 1993).Little is known about the molecular basis of ovule development. Recently, severa1 laboratories have taken a genetic To whom correspondence should be addressed approach to understand the genetic circuitry used in the developing ovule and to identify potential communication between the diploid ovule and the haploid female gametophyte. A number of sporophytic mutants have been identified in Arabidopsis that specifically affect the ovule and/or the female gametophyte. In belll (bell) plants, ovules lack an inner integument, the outer in...

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Section: Ant Has a Role In Floral Organ Developmentmentioning

confidence: 93%

The AINTEGUMENTA gene of Arabidopsis required for ovule and female gametophyte development is related to the floral homeotic gene APETALA2.

et al. 1996

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“…That only a limited number of genes specifically affecting meristem development have been identified to date suggests either that genetic screens have not reached saturation or that many of the other regulatory genes are redundantly encoded or are involved in a number of other processes, thereby obscuring their roles in meristem development. For example, genes with pleiotropic mutant defects, such as REVOLUTA (Talbert et al, 1995), FOREVER YOUNG (Callos et al, 1994), FASClATA7, and FASClATA2 (Leyser and Furner, 1992), may encode proteins that function in meristem regulation.…”

Section: Perspectivesmentioning

confidence: 99%

Organ Formation at the Vegetative Shoot Meristem.

Clark

1997

Plant Cell

132

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OVERVIEWIn higher plants, organ formation is critical for generating the vegetative portion of the plant. Above-ground organ formation occurs at a collection of stem cells termed the shoot meristem (SM), which is established during embryogenesis. How the SM functions as a site of continuous organ formation is a central question for plant developmental biology. This is not only because all above-ground organs are initiated by the SM but also because their position and identity are established there.The SM retains the capability to form organs through two fundamental processes (Figure 1). The first function of the SM is to maintain a pool of undifferentiated cells. Without undifferentiated cells to draw upon, new organ initiation would not be possible. The second process is to direct appropriately positioned undifferentiated cells toward organ formation and eventual differentiation. Although the structure of meristems is variable across the plant kingdom, all complex multicellular plants regulate the balance between an undifferentiated and differentiated fate at their respective meristems. Thus, unraveling the mechanisms by which model plants such as Arabidopsis regulate meristem development is expected to have implications for a wide variety of plant species.The SM has been the focus of many studies over the past several decades. These studies have investigated the diversity, morphology, histology, cell division patterns, and cell lineages of the SM. Because this work has been summarized in detail elsewhere (Steeves and Sussex, 1989; Lyndon, 1990Lyndon, , 1994, this review focuses on recent advances in understanding the genetic control of organ formation at the SM. MERISTEM STRUCTUREThe SM can be divided conceptually into several regions (Figure 1 C). The distinctions between the inner two regions, the central zone (Cz) and the peripheral zone (PZ), are

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“…The CZ has been thought to harbor a set of initials, which divide and displace their daughters into the PZ, where they are incorporated into the primordia of leaves and flowers at defined locations. Starting just after germination, the first four leaves are formed as opposite pairs, and then subsequent leaves and flowers are formed in a spiral pattern with an angle close to 137.5°between consecutive primordia (Callos et al, 1994). The SAM retains a nearly constant size from germination to senescence, despite a constant flux of cells from the meristem to newly established lateral organs and underlying stem.…”

Section: Introductionmentioning

confidence: 99%

Real-time lineage analysis reveals oriented cell divisions associated with morphogenesis at the shoot apex ofArabidopsis thaliana

et al. 2004

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Precise knowledge of spatial and temporal patterns of cell division,including number and orientation of divisions, and knowledge of cell expansion, is central to understanding morphogenesis. Our current knowledge of cell division patterns during plant and animal morphogenesis is largely deduced from analysis of clonal shapes and sizes. But such an analysis can reveal only the number, not the orientation or exact rate, of cell divisions. In this study, we have analyzed growth in real time by monitoring individual cell divisions in the shoot apical meristems (SAMs) of Arabidopsis thaliana. The live imaging technique has led to the development of a spatial and temporal map of cell division patterns. We have integrated cell behavior over time to visualize growth. Our analysis reveals temporal variation in mitotic activity and the cell division is coordinated across clonally distinct layers of cells. Temporal variation in mitotic activity is not correlated to the estimated plastochron length and diurnal rhythms. Cell division rates vary across the SAM surface. Cells in the peripheral zone (PZ)divide at a faster rate than in the central zone (CZ). Cell division rates in the CZ are relatively heterogeneous when compared with PZ cells. We have analyzed the cell behavior associated with flower primordium development starting from a stage at which the future flower comprises four cells in the L1 epidermal layer. Primordium development is a sequential process linked to distinct cellular behavior. Oriented cell divisions, in primordial progenitors and in cells located proximal to them, are associated with initial primordial outgrowth. The oriented cell divisions are followed by a rapid burst of cell expansion and cell division, which transforms a flower primordium into a three-dimensional flower bud. Distinct lack of cell expansion is seen in a narrow band of cells, which forms the boundary region between developing flower bud and the SAM. We discuss these results in the context of SAM morphogenesis.

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The forever young gene encodes an oxidoreductase required for proper development of the Arabidopsis vegetative shoot apex

Cited by 29 publications

References 36 publications

The AINTEGUMENTA gene of Arabidopsis required for ovule and female gametophyte development is related to the floral homeotic gene APETALA2.

The AINTEGUMENTA gene of Arabidopsis required for ovule and female gametophyte development is related to the floral homeotic gene APETALA2.

Organ Formation at the Vegetative Shoot Meristem.

Real-time lineage analysis reveals oriented cell divisions associated with morphogenesis at the shoot apex ofArabidopsis thaliana

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