Genetics of Floral Development and Patterning (original) (raw)
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Flower Development: Initiation, Differentiation, and Diversification
Annual Review of Cell and Developmental Biology, 2003
▪ Flowering is one of the most intensively studied processes in plant development. Despite the wide diversity in floral forms, flowers have a simple stereotypical architecture. Flowers develop from florally determined meristems. These small populations of cells proliferate to form the floral organs, including the sterile outer organs, the sepals and petals, and the inner reproductive organs, the stamens and carpels. In the past decade, analyses of key flowering genes have been carried out primarily in Arabidopsis and have provided a foundation for understanding the underlying molecular genetic mechanisms controlling different aspects of floral development. Such studies have illuminated the transcriptional cascades responsible for the regulation of these key genes, as well as how these genes effect their functions. In turn, these studies have resulted in the refinement of the original ideas of how flowers develop and have indicated the gaps in our knowledge that need to be addressed.
BMC Plant Biology
Background: The Arabidopsis FILAMENTOUS FLOWER (FIL) gene encodes a YABBY (YAB) family putative transcription factor that has been implicated in specifying abaxial cell identities and thus regulating organ polarity of lateral organs. In contrast to double mutants of fil and other YAB genes, fil single mutants display mainly floral and inflorescence morphological defects that do not reflect merely a loss of abaxial identity. Recently, FIL and other YABs have been shown to regulate meristem organization in a non-cell-autonomous manner. In a screen for new mutations affecting floral organ morphology and development, we have identified a novel allele of FIL, fil-9 and characterized its floral and meristem phenotypes.
Unusual Floral Organs Controls Meristem Identity and Organ Primordia Fate in Arabidopsis
The Plant Cell, 1995
A nove1 gene that is involved in regulating flower initiation and development has been identified in Arabidopsis. This gene has been designated UNUSUAL FLORAL ORGANS (UFO), with five corresponding nuclear recessive alleles designated ufo-1 to ufo-5. Under short day-length conditions, ufo homozygotes generate more coflorescences than do the wild type, and coflorescences often appear apical to the first floral shoot, resulting in a period of inflorescence development in which regions of floral and coflorescence shoots are produced alternately. ufo enhances the phenotype of weak leafy alleles, and the double mutant Ufo-1 Apetalal-1 produces only coflorescence-like shoots, suggesting that these two genes control different aspects of floral initiation. Floral development was also altered in Ufo plants. Ufo flowers have an altered organ number in all whorls, and organs in the first, second, and third whorls exhibit variable homeotic transformations. Ufo single and double mutant phenotypes suggest that the floral changes result from reduction in class B floral homeotic gene expression and fluctuations in the expression boundaries of class C function and FLO10. Surprisingly, in situ hybridization analysis revealed no obvious differences in expression pattern or level in developing Ufo flowers compared with that of the wild type for any class B or C gene studied. We propose that UFO acts in concert with known floral initiation genes and regulates the domains of floral homeotic gene function.
The Plant Cell, 1999
Phenotypic analysis of single and multiple mutants as well as in situ localization analysis of the expression patterns of floral genes have revealed that the FILAMENTOUS FLOWER (FIL) gene plays important roles in establishing the inflorescence in Arabidopsis. As previously reported, the fil mutant generates clusters of both filamentous structures and flowers with floral organs of altered number and shape. The structural resemblance of the filamentous structures to peduncles and the expression pattern of the APETALA1 (AP1) gene have shown that these filamentous structures are underdeveloped flowers that fail to form receptacles and floral organs, indicating that one of the roles of the FIL gene is to support the development of the floral meristem. That FIL also is involved in fate determination in the floral meristem is demonstrated by the homeotic conversion of flowers to inflorescences in fil ap1 double mutants and in fil ap1 cauliflower triple mutants. In double mutants with flowering-time loci (i.e., ft or fwa), leafy (lfy), and unusual floral organs (ufo) , filamentous structures are formed, but very few or no flowers with floral organs develop. The enhanced phenotype in the fil ap1 and the fil lfy double mutants suggests that the FIL protein may work together with AP1 and LFY proteins. The FIL gene also may be involved in the cell fate determination of floral organ primordia, possibly by controlling the spatial expression patterns of the class A and C floral organ identity genes.
The Plant Journal, 1999
SummaryGenetic and molecular studies have suggested that the UNUSUAL FLORAL ORGANS (UFO) gene, from Arabidopsis thaliana, is expressed in all shoot apical meristems, and is involved in the regulation of a complex set of developmental events during floral development, including floral meristem and floral organ identity. Results from in situ hybridization using genes expressed early in floral development as probes indicate that UFO controls growth of young floral primordia. Transgenic constructs were used to provide evidence that UFO regulates floral organ identity by activating or maintaining transcription of the class B organ‐identity gene APETALA 3, but not PISTILLATA. In an attempt to understand the biochemical mode of action of the UFO gene product, we show here that UFO is an F‐box protein that interacts with Arabidopsis SKP1‐like proteins, both in the yeast two‐hybrid system and in vitro. In yeast and other organisms both F‐box proteins and SKP1 homologues are subunits of speci...
Plant reproduction, 2017
Linear modelling approaches detected significant gradients in organ growth and patterning across early flowers of the Arabidopsis inflorescence and uncovered evidence of new roles for gibberellin in floral development. Most flowering plants, including the genetic model Arabidopsis thaliana, produce multiple flowers in sequence from a reproductive shoot apex to form a flower spike (inflorescence). The development of individual flowers on an Arabidopsis inflorescence has typically been considered as highly stereotypical and uniform, but this assumption is contradicted by the existence of mutants with phenotypes visible in early flowers only. This phenomenon is demonstrated by mutants partially impaired in the biosynthesis of the phytohormone gibberellin (GA), in which floral organ growth is retarded in the first flowers to be produced but has recovered spontaneously by the 10th flower. We presently lack systematic data from multiple flowers across the Arabidopsis inflorescence to expl...
Flower development: open questions and future directions
Methods in molecular biology (Clifton, N.J.), 2014
Almost three decades of genetic and molecular analyses have resulted in detailed insights into many of the processes that take place during flower development and in the identification of a large number of key regulatory genes that control these processes. Despite this impressive progress, many questions about how flower development is controlled in different angiosperm species remain unanswered. In this chapter, we discuss some of these open questions and the experimental strategies with which they could be addressed. Specifically, we focus on the areas of floral meristem development and patterning, floral organ specification and differentiation, as well as on the molecular mechanisms underlying the evolutionary changes that have led to the astounding variations in flower size and architecture among extant and extinct angiosperms.
LEAFY controls floral meristem identity in Arabidopsis
Cell, 1992
The first step in flower development is the generation of a floral meristem by the inflorescence meristem. We have analyzed how this process is affected by mutant alleles of the Arabidopsis gene LEAFY. We show that LEAFY interacts with another floral control gene, APETALAl, to promote the transition from inflorescence to floral meristem. We have cloned the LEAFY gene, and, consistent with the mutant phenotype, we find that LEAFY RNA is expressed strongly in young flower primordia. LEAFY expression precedes expression of the homeotic genes AGAMOUS and APET-ALA3, which specify organ identity within the flower. Furthermore, we demonstrate that LEAFY is the Arabidopsis homolog of the FLORKAULA gene, which controls floral meristem identity in the distantly related species Antirrhinum majus.
The making of a flower: control of floral meristem identity in
1999
During the reproductive phase of a plant, shoot meristems follow one of two developmental programs to produce either flowers or vegetative shoots. The decision as to which meristems give rise to flowers, and when they do so, determines the general morphology of an inflorescence. Molecular and genetic research in Arabidopsis and other model species has identified several genes that control the identity that a meristem will adopt. These meristem identity genes are activated in response to developmental and environmental cues, and can be assigned to three basic categories: those required either to initiate or maintain the floral program in some meristems and those required to maintain the vegetative program in others.