The flowering process of Vitis vinifera: A review (original) (raw)
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Flower Development and Regulation of Flowering
Four concentric whorls around the flanks of the meristem develop to form a typical flower in angiosperms. From outer most to innermost, these four whorls are fated to become sepals, petals, stamens and ovary with two fused carpels. According to ABC model of flower development, three regions of floral meristem (A, B and C) and three types of genes (a, b and c) acting in these regions have regulatory functions. With the discovery of another class (E) of genes, a revised model, called ABCE model, was put forth which envisages four activities (A, B, C and E) around the four whorls in the flower. The specific function of four organs, namely, sepals, petals, stamens, and carpels, is based on the combination of these four activities in the flower. Initiation of flowering requires a shift from vegetative to reproductive phase. The multiprotein complexes of MADS-box proteins initiate the formation of concentric four whorls around the flower. The foremost step in reproduction is floral transition with the interplay activity of numerous external and internal signals. Flowers are derived from SAM. The emergence through environmental signals followed by changes in meristem and organ identity, stem cell termination and organogenesis mark the flower development process. The flower repression occurs only under specific environmental and developmental stage. Flowering time in non-inductive photoperiodic conditions need to be understood. The floral integrator gene Flowering locus T (FT) control flowering time in numerous plant species. FLOWERING LOCUS C (FLC) encodes a MADS domain protein that acts as a suppressor of flowering. The flowering time genes are involved in longday photoperiod, gibberellin, autonomous, and vernalization pathway. FLC regulation led to the emergence of chromatin-modifying systems that control the developmental shift from vegetative to flowering transition in plants. The suppressive H3K27me3 mark not only acts during floral induction by regulating FLC expression, and floral meristem recognition through leafy (LFY), it also contributes in the organogenesis during flower H3K4 demethylation, histone H3 Lysine-9 (H3K9) and H3 Lysine 27 (H3K27) methylation, and histone Arginine (R) methylation. The H3K4 hyper-trimethylation of FLC chromatin also corresponds to the flowering delay in winter-annual Arabidopsis. FLC in the Arabidopsis is suppressed by histone modifications through Vernalization 2 (VRN2) protein complex. The epigenetic factors reduce the flowering repression in winter to allow them to flower in spring season. Epigenetic modifications lead to the floral initiation and development through chromatin modifications under stress. The epigenetic mechanisms play vital role in the control of photoperiodic flowering. The genetic and epigenetic control on the complex network of flowering-regulatory mechanisms initiates flower formation in diverse plants, the understanding of which would be useful in future for elucidating the regulatory mechanism for better agricultural production.
Molecular basis of flower initiation—A review
Plants have many differences, like protandry, protogyny, etc. However, amidst these differences, all angiosperms have a common mechanism of flowering, i.e. concentric pattern of flowering (sepal, petal, stamen and carpel). The mechanism or the genes thorough which plants maintain boundaries between the four, sepal-petal-stamen-carpel, are also given due importance. Once a plant attains competence, flowers may be produced through the reorganization of SAM directly to floral meristem, or through the inflorescence or co-inflorescence meristem, in response of exogenous and endogenous signals. Initiation, determination and differentiation are classed into four stages and this is the region which is studied here in detail. Some organ specificity genes, like MALE STERILITY (MS) and BICAUDAL (BIC), move us towards a better understanding of the mechanism like male sterility and self-incompatibility in plants. Models like ABC, biophysical, MCDK, etc., help in explaining the mechanism of flowe...
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.
A Parade on Molecular Control of Flowering
International Journal of Environment, Agriculture and Biotechnology, 2016
Flower is a reproductive part of plant which contains complex array of functionally specialized structures.Photoperiodism, or the ability of an organism to detect day length, makes it possible for an event to occur at a particular time of year, thus allowing for a seasonal response. Circadian rhythms and photoperiodism have the common property of responding to cycles of light and darkness. Plant physiologists believed that the correlation between long days and flowering was a consequence of the accumulation of photosynthetic products synthesized during long days. Vernalization causes stable changes in the pattern of gene expression in the meristem, gene expression that are still stable even after vernalization is removed. The organ identity genes initially were identified through mutations that dramatically alter the structure and thus the identity of the floral organs produced in two adjacent whorls. The patterns of organ formation in the wild type and most of the mutant phenotypes are predicted and explained by ABC model of flower development. the transition to flowering involves a complex system of interacting factors that include among carbohydrates, gibberellins, cytokinins, bromeliads and ethylene.
The Arabidopsis Book …, 2010
Some of the authors of this publication are also working on these related projects: evolution of gene networks regulating carpel development View project A computational model for angiogenesis and hemodynamics View project Adriana Corvera Universidad Nacional Autónoma de México 5 PUBLICATIONS 99 CITATIONS SEE PROFILE
Organ identity genes and modified patterns of flower development inGerbera hybrida(Asteraceae)
The Plant Journal, 1999
We have used Gerbera hybrida (the cultivated ornamental, gerbera) to investigate the molecular basis of flower development in Asteraceae, a family of flowering plants that have heteromorphic flowers and specialized floral organs. Flowers of the same genotype may differ in a number of parameters, including sex expression, symmetry, sympetaly and pigmentation. In order to study the role of organ identity determination in these phenomena we isolated and functionally analysed six MADS box genes from gerbera; these were shown by phylogenetic analysis to be orthologous to well characterized regulatory genes described from Arabidopsis and Antirrhinum. Expression analysis suggests that the two gerbera agamous orthologues, the globosa orthologue and one of the deficiens orthologues may have functional equivalency to their counterparts, participating in the C and B functions, respectively. However, the function of a second deficiens orthologue appears unrelated to the B function, and that of a squamosa orthologue seems distinct from squamosa as well as from the A function. The induction patterns of gerbera MADS box genes conform spatiotemporally to the multi-flowered, head-like inflorescence typical of Asteraceae. Furthermore, gerbera plants transgenic for the newly isolated MADS box genes shed light onto the mechanistic basis for some floral characteristics that are typical for Asteraceae. We can conclude, therefore, that the pappus bristles are sepals highly modified for seed dispersal, and that organ abortion in the female marginal flowers is dependent upon organ
Regulation of floral initiation in horticultural trees
Journal of Experimental Botany, 2008
The intention of this review is to discuss floral initiation of horticultural trees. Floral initiation is best understood for herbaceous species, especially at the molecular level, so a brief overview of the control of floral initiation of Arabidopsis (Arabidopsis thaliana (L.) Heynh.) precedes the discussion of trees. Four major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod and temperature, autonomous floral initiation, and regulation by gibberellins. Tropical trees are generally induced to flower through environmental cues, whereas floral initiation of temperate deciduous trees is often autonomous. In the tropical evergreen tree mango, Mangifera indica L., cool temperature is the only factor known to induce flowering, but does not ensure floral initiation will occur because there are important interactions with vegetative growth. The temperate deciduous tree apple, Malus domestica Borkh., flowers autonomously, with floral initiation dependent on aspects of vegetative development in the growing season before anthesis, although with respect to the floral initiation of trees in general: the effect of the environment, interactions with vegetative growth, the roles of plant growth regulators and carbohydrates, and recent advances in molecular biology, are discussed.
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.