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Charles S. Gasser - One of the best experts on this subject based on the ideXlab platform.
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Development and evolution of the unique Ovules of flowering plants.
Current Topics in Developmental Biology, 2018Co-Authors: Charles S. Gasser, Debra J. SkinnerAbstract:Abstract Ovules are the precursors to seeds and as such are critical to plant propagation and food production. Mutant studies have led to the identification of numerous genes regulating Ovule development. Genes encoding transcription factors have been shown to direct Ovule spacing, Ovule identity and integument formation. Particular co-regulators have now been associated with activities of some of these transcription factors, and other protein families including cell surface receptors have been shown to regulate Ovule development. Hormone levels and transport, especially of auxin, have also been shown to play critical roles in Ovule emergence and morphogenesis and to interact with the transcriptional regulators. Ovule diversification has been studied using orthologs of regulatory genes in divergent angiosperm groups. Combining modern genetic evidence with expanding knowledge of the fossil record illuminates the possible origin of the unique bitegmic Ovules of angiosperms.
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Expression of Ovule and integument‐associated genes in reduced Ovules of Santalales
Evolution & Development, 2010Co-Authors: Ryan H. Brown, Daniel L. Nickrent, Charles S. GasserAbstract:1Present address: National Small Grains Germplasm Research Facility, USDA-ARS, Aberdeen, ID 83210, USA SUMMARY Santalales comprise mainly parasitic plants including mistletoes and sandalwoods. Bitegmic Ovules similar to those found in most other angiosperms are seen in many members of the order, but other members exhibit evolutionary reductions to the unitegmic and ategmic conditions. In some mistletoes, extreme reduction has resulted in the absence of emergent Ovules such that embryo sacs appear to remain embedded in placental tissues. Three santalalean representatives (Comandra, Santalum, and Phoradendron), displaying unitegmic, and ategmic Ovules, were studied. Observed Ovule morphologies were consistent with published reports, including Phoradendron serotinum, which we interpret as having reduced ategmic Ovules, consistent with earlier reports on this species. For further understanding of the nature of the Ovule reductions we isolated orthologs of the Arabidopsis genes AINTEGUMENTA (ANT) and BELL1 (BEL1), which are associated with Ovule development in this species. We observed ovular expression of ANT and BEL1 in patterns largely resembling those seen in the integumented Ovules of Arabidopsis. These genes were found to be expressed in the integument of unitegmic Ovules and in the surface layers of ategmic Ovules, and in some cases, expression of BEL1 was also observed in the surrounding carpel tissue. We hypothesize that ategmic Ovules derive from a fusion of the integuments with the nucellus or that the nucellus has taken on some of the characteristics confined to integuments in ancestral species.
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Ovule development genetic trends and evolutionary considerations
Sexual Plant Reproduction, 2009Co-Authors: Dior R Kelley, Charles S. GasserAbstract:Much of our current understanding of Ovule development in flowering pants is derived from genetic and molecular studies performed on Arabidopsis thaliana. Arabidopsis has bitegmic, anatropous Ovules, representing both the most common and the putative ancestral state among angiosperms. These studies show that key genetic determinants that act to control morphogenesis during Ovule development also play roles in vegetative organ formation, consistent with Goethe’s “everything is a leaf” concept. Additionally, the existence of a common set of genetic factors that underlie laminar growth in angiosperms fits well with hypotheses of homology between integuments and leaves. Utilizing Arabidopsis as a reference, researchers are now investigating taxa with varied Ovule morphologies to uncover common and diverged mechanisms of Ovule development.
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expression based discovery of candidate Ovule development regulators through transcriptional profiling of Ovule mutants
BMC Plant Biology, 2009Co-Authors: Debra J. Skinner, Charles S. GasserAbstract:Background Arabidopsis Ovules comprise four morphologically distinct parts: the nucellus, which contains the embryo sac, two integuments that become the seed coat, and the funiculus that anchors the Ovule within the carpel. Analysis of developmental mutants has shown that Ovule morphogenesis relies on tightly regulated genetic interactions that can serve as a model for developmental regulation. Redundancy, pleiotropic effects and subtle phenotypes may preclude identification of mutants affecting some processes in screens for phenotypic changes. Expression-based gene discovery can be used access such obscured genes.
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genetic analysis of Ovule development
Annual review of plant physiology and plant molecular biology, 1998Co-Authors: Charles S. Gasser, Jean Broadhvest, Bernard A. HauserAbstract:▪ Abstract Ovules are the direct precursors of seeds and thus play central roles in sexual plant reproduction and human nutrition. Extensive classical studies have elucidated the evolutionary trends and developmental processes responsible for the current wide variety of Ovule morphologies. Recently, Ovules have been perceived as an attractive system for the study of genetic regulation of plant development. More than a dozen regulatory genes have now been identified through isolation of Ovule mutants. Characterization of these mutants shows that some aspects of Ovule development follow independent pathways, while other processes are interdependent. Some of these mutants have Ovules resembling those of putative ancestors of angiosperms and may help in understanding plant evolution. Clones of several of the regulatory genes have been used to determine expression patterns and putative biochemical functions of the gene products. Newly constructed models of genetic regulation of Ovule development provide a fram...
Kay Schneitz - One of the best experts on this subject based on the ideXlab platform.
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Microscopic Analysis of Arabidopsis Ovules
Methods of Molecular Biology, 2013Co-Authors: Balaji Enugutti, Kay SchneitzAbstract:Ovules are the major female reproductive organs in higher plants. Furthermore, Ovules of Arabidopsis thaliana are successfully used as model system to study plant organogenesis. Here we describe two microscopic techniques to analyze Ovule development in Arabidopsis. Both methods involve fixed specimens and allow rapid, easy, and reproducible morphological comparisons between wild-type and mutant Ovule development.
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Microscopic Analysis of Ovule Development in Arabidopsis thaliana
Methods of Molecular Biology, 2012Co-Authors: Balaji Enugutti, Maxi Oelschner, Kay SchneitzAbstract:Ovules are the major female reproductive organs in higher plants. In addition, Ovules of Arabidopsis thaliana are successfully used as model system to study plant organogenesis. Here we describe two microscopic techniques to analyze Arabidopsis Ovule development from the organ to the cellular level in a rapid and reproducible fashion. Both methods are of great value when comparing the morphology of wild-type and mutant Ovule development.
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pattern formation during early Ovule development in arabidopsis thaliana
Developmental Biology, 2004Co-Authors: Patrick Sieber, Kay Schneitz, Jacqueline Gheyselinck, Rita Grosshardt, Thomas Laux, Ueli GrossniklausAbstract:Abstract Ovules of higher plants are the precursors of seeds. Ovules emerge from placental tissue inside the gynoecium of flowers. Three elements, funiculus, chalaza, and nucellus, can be distinguished along the proximal–distal axis of the outgrowing radially symmetrical Ovule primordium. The asymmetric initiation of the outer integument marks the switch to adaxial–abaxial development, which leads to the formation of a bilaterally symmetrical Ovule. The putative transcriptional regulator NOZZLE (NZZ) plays a role in mediating this transition by controlling the timing of expression of the putative transcriptional regulator INNER NO OUTER (INO) in an abaxial domain of the chalaza, from where the outer integument initiates. Integument formation depends on the homeobox gene WUSCHEL (WUS), which is expressed in the nucellus and is sufficient to induce integuments non-cell autonomously from a region adjacent to its expression domain. In this study, we describe the expression pattern of the homeobox-leucine zipper gene PHABULOSA (PHB) during Ovule development, demonstrating that adaxial–abaxial polarity is established from the very beginning of Ovule development. Furthermore, we examined the expression pattern of PHB, INO, and WUS in Ovules of plants, which are affected in integument initiation and thus defective in the transition from proximal–distal to adaxial–abaxial development. We found that NZZ is required to restrict PHB expression to the distal chalaza, from where the inner integument initiates. PHB expression is not established in the distal chalaza of two mutants, aintegumenta (ant) and wus, which fail to form integuments. Furthermore, we suggest that one mechanism by which WUS controls integument formation is by establishing the chalaza and that outer and inner integument identity determination depends on additional region-specific factors. In addition, we present evidence that NZZ is essential for the normal nucellar expression pattern of WUS. Thus, both WUS and PHB affect processes downstream of NZZ action during the transition from proximal–distal to adaxial–abaxial Ovule development.
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dissection of sexual organ ontogenesis a genetic analysis of Ovule development in arabidopsis thaliana
Development, 1997Co-Authors: Kay Schneitz, Martin Hulskamp, Steven D Kopczak, Robert E PruittAbstract:Understanding organogenesis remains a major challenge in biology. Specification, initiation, pattern formation and cellular morphogenesis, have to be integrated to generate the final three-dimensional architecture of a multicellular organ. To tackle this problem we have chosen the Ovules of the flowering plant Arabidopsis thaliana as a model system. In a first step towards a functional analysis of Ovule development, we performed a large-scale genetic screen and isolated a number of sterile mutants with aberrant Ovule development, We provide indirect genetic evidence for the existence of proximal-distal pattern formation in the Arabidopsis Ovule primordium. The analysis of the mutants has identified genes that act at an intermediate regulatory level and control initiation of morphogenesis in response to proximal-distal patterning. A second group of genes functions at a subordinate control level and regulates general cellular processes of morphogenesis. A large group of male and female sterile mutants shows defects restricted to early or late gametogenesis. In addition, we propose that the mature Ovule obtains its overall curved shape by at least three different processes that act in only one domain of the Ovule.
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wild type Ovule development in arabidopsis thaliana a light microscope study of cleared whole mount tissue
Plant Journal, 1995Co-Authors: Kay Schneitz, Martin Hulskamp, Robert E PruittAbstract:A detailed morphological description of wild-type Ovule development in Arabidopsis thaliana is presented. The entire process from the formation of the Ovule protrusion until the eight-nuclear endosperm stage is described. The study is based on a light-microscopical analysis of stained and subsequently optically cleared whole-mount Ovules. It is supplemented by confocal laser scanning microscopy of propidium iodide-stained whole-mount Ovules. It has been shown that the combination of both techniques eliminates the need for sections to a large extent, and hence allows the rapid morphological inspection of a large number of Ovules in Arabidopsis. The Ovule constitutes a relatively simple organ. During development, three discrete major pattern elements are laid down along the proximal-distal axis: the nucellus at the distal end (harbors the megaspore/gametophyte lineage), the chalaza (flanked by the integuments) and the funiculus (includes the vascular strand) at the proximal end. These three pattern elements already appear at a very early stage, when the initially formed protrusion, consisting of files of uniform cells, is transformed into a patterned primordium. Subsequent morphogenesis results in the manifestation of the morphological characters of each pattern element. It was possible to dissect this developmental process into distinct, morphologically discernible steps at a high resolution. A classification scheme of Ovule developmental stages is proposed, which is based on Ovule-specific, discrete, and easy-to-score markers.
Jeffrey Z Chen - One of the best experts on this subject based on the ideXlab platform.
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dynamic roles for small rnas and dna methylation during Ovule and fiber development in allotetraploid cotton
PLOS Genetics, 2015Co-Authors: Qingxin Song, Xueying Guan, Jeffrey Z ChenAbstract:DNA methylation is essential for plant and animal development. In plants, methylation occurs at CG, CHG, and CHH (H = A, C or T) sites via distinct pathways. Cotton is an allotetraploid consisting of two progenitor genomes. Each cotton fiber is a rapidly-elongating cell derived from the Ovule epidermis, but the molecular basis for this developmental transition is unknown. Here we analyzed methylome, transcriptome, and small RNAome and revealed distinct changes in CHH methylation during Ovule and fiber development. In Ovules, CHH hypermethylation in promoters correlated positively with siRNAs, inducing RNA-dependent DNA methylation (RdDM), and up-regulation of Ovule-preferred genes. In fibers, the Ovule-derived cells generated additional heterochromatic CHH hypermethylation independent of RdDM, which repressed transposable elements (TEs) and nearby genes including fiber-related genes. Furthermore, CHG and CHH methylation in genic regions contributed to homoeolog expression bias in Ovules and fibers. Inhibiting DNA methylation using 5-aza-2'-deoxycytidine in cultured Ovules has reduced fiber cell number and length, suggesting a potential role for DNA methylation in fiber development. Thus, RdDM-dependent methylation in promoters and RdDM-independent methylation in TEs and nearby genes could act as a double-lock feedback mechanism to mediate gene and TE expression, potentiating the transition from epidermal to fiber cells during Ovule and seed development.
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genome wide analysis reveals rapid and dynamic changes in mirna and sirna sequence and expression during Ovule and fiber development in allotetraploid cotton gossypium hirsutum l
Genome Biology, 2009Co-Authors: Mingxiong Pang, Xueying Guan, Andrew W Woodward, Vikram Agarwal, Misook Ha, Vanitharani Ramachandran, Xuemei Chen, Barbara A Triplett, David M Stelly, Jeffrey Z ChenAbstract:Background: Cotton fiber development undergoes rapid and dynamic changes in a single cell type, from fiber initiation, elongation, primary and secondary wall biosynthesis, to fiber maturation. Previous studies showed that cotton genes encoding putative MYB transcription factors and phytohormone responsive factors were induced during early stages of Ovule and fiber development. Many of these factors are targets of microRNAs (miRNAs) that mediate target gene regulation by mRNA degradation or translational repression. Results: Here we sequenced and analyzed over 4 million small RNAs derived from fiber and nonfiber tissues in cotton. The 24-nucleotide small interfering RNAs (siRNAs) were more abundant and highly enriched in Ovules and fiber-bearing Ovules relative to leaves. A total of 31 miRNA families, including 27 conserved, 4 novel miRNA families and a candidate-novel miRNA, were identified in at least one of the cotton tissues examined. Among 32 miRNA precursors representing 19 unique miRNA families identified, 7 were previously reported, and 25 new miRNA precursors were found in this study. Sequencing, miRNA microarray, and small RNA blot analyses showed a trend of repression of miRNAs, including novel miRNAs, during Ovule and fiber development, which correlated with upregulation of several target genes tested. Moreover, 223 targets of cotton miRNAs were predicted from the expressed sequence tags derived from cotton tissues, including Ovules and fibers. The cotton miRNAs examined triggered cleavage in the predicted sites of the putative cotton targets in Ovules and fibers.
Koji Murai - One of the best experts on this subject based on the ideXlab platform.
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Class D and B_sister MADS-box genes are associated with ectopic Ovule formation in the pistil-like stamens of alloplasmic wheat (Triticum aestivum L.)
Plant Molecular Biology, 2009Co-Authors: Kaori Yamada, Tatsunori Saraike, Naoki Shitsukawa, Chizuru Hirabayashi, Shigeo Takumi, Koji MuraiAbstract:Homeotic transformation of stamens into pistil-like structures (pistillody) has been reported in cytoplasmic substitution (alloplasmic) lines of bread wheat ( Triticum aestivum L.) that have the cytoplasm of a related wild species, Aegilops crassa . An ectopic Ovule differentiates in the pistil-like stamen in the alloplasmic wheat. The SEEDSTICK ( STK )—like class D MADS-box gene, wheat STK ( WSTK ), was expressed in the primordia of ectopic Ovules in the pistil-like stamens as well as in the true pistil, suggesting that ectopic Ovule formation results from WSTK expression in the pistil-like stamens of alloplasmic wheat. The ectopic Ovule is abnormal as it fails to form complete integuments. Based on the expression pattern of WSTK and B_sister MADS-box gene, WBsis ( wheat B _ sister ), we conclude that WSTK plays a role in determination of Ovule identity in the pistil-like stamen, but complete Ovule development fails due to aberrant expression of WBsis .
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class d and bsister mads box genes are associated with ectopic Ovule formation in the pistil like stamens of alloplasmic wheat triticum aestivum l
Plant Molecular Biology, 2009Co-Authors: Kaori Yamada, Tatsunori Saraike, Naoki Shitsukawa, Chizuru Hirabayashi, Shigeo Takumi, Koji MuraiAbstract:Homeotic transformation of stamens into pistil-like structures (pistillody) has been reported in cytoplasmic substitution (alloplasmic) lines of bread wheat (Triticum aestivum L.) that have the cytoplasm of a related wild species, Aegilops crassa. An ectopic Ovule differentiates in the pistil-like stamen in the alloplasmic wheat. The SEEDSTICK (STK)—like class D MADS-box gene, wheat STK (WSTK), was expressed in the primordia of ectopic Ovules in the pistil-like stamens as well as in the true pistil, suggesting that ectopic Ovule formation results from WSTK expression in the pistil-like stamens of alloplasmic wheat. The ectopic Ovule is abnormal as it fails to form complete integuments. Based on the expression pattern of WSTK and Bsister MADS-box gene, WBsis (wheat Bsister), we conclude that WSTK plays a role in determination of Ovule identity in the pistil-like stamen, but complete Ovule development fails due to aberrant expression of WBsis.
Lucia Colombo - One of the best experts on this subject based on the ideXlab platform.
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Ovule integument identity determination in Arabidopsis.
Plant Signaling & Behavior, 2020Co-Authors: Vittoria Brambilla, Martin M Kater, Lucia ColomboAbstract:Ovules are the organs in which the female gametophyte develops. They develop in Arabidopsis and many other plant species from carpel tissue as new meristematic formations. In Ovules we can distinguish three major parts which are the funiculus that attaches the Ovule to the placenta, the integuments and the nucellus which contains the female gametophyte. Little is known about the molecular genetic regulatory cues that control the development of these Ovule tissues. In the August issue of The Plant Cell, we have shown that there are genetic and molecular interactions between BELL1 and the MADS-box genes AGAMOUS, SEEDSTICK, SHATTERPROOF1 and SHATTERPROOF2 to control integument identity.1 We have shown that BEL1 directly interacts with a MADS-box dimer composed of AG and SEPALLATA3 and we proposed that this interaction is essential to prevent that integuments turn into carpels. Furthermore, we have shown that during Ovule development BEL1 is important for the regulation of the stem cell maintenance gene WUSCHEL. In this Addendum we discuss addition literature data that sustain our model for integument development in Arabidopsis.
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Ovule development a new model for lateral organ formation
Frontiers in Plant Science, 2014Co-Authors: Mara Cucinotta, Lucia Colombo, Irma RoigvillanovaAbstract:In spermatophytes the Ovules upon fertilization give rise to the seeds. It is essential to understand the mechanisms that control Ovule number and development as they ultimately determine the final number of seeds and, thereby, the yield in crop plants. In Arabidopsis thaliana, Ovules arise laterally from a meristematic tissue within the carpel referred to as placenta. For a correct determination of the number of Ovules, a precise establishment of the positions where Ovule primordia emerge is needed, and a tight definition of the boundaries between Ovules is therefore also required. In the last decades, few factors have been identified to be involved in the determination of Ovule number. Recently, plant hormones have also been revealed as fundamental players in the control of the initiation of Ovule formation. In this review we summarize the current knowledge about both the molecular and hormonal mechanisms that control Ovule formation in Arabidopsis thaliana.
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arabidopsis Ovule development and its evolutionary conservation
Trends in Plant Science, 2008Co-Authors: Lucia Colombo, Raffaella Battaglia, Martin M KaterAbstract:Ovules have an important role during the life cycle of the plant, and they provide an excellent model for studying organogenesis in plants. As such, the molecular control of Ovule development has been studied for many years. Recent studies in Arabidopsis have revealed important new data concerning Ovule primordia formation, Ovule identity determination, and patterning. Furthermore, interesting results about Ovule development in other species, such as Petunia and rice, have been published recently. In this review, we discuss these recent findings in reference to Ovule development in Arabidopsis. We compare available data with those of other species to investigate the evolutionary conservation of the regulatory pathways.
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the d lineage mads box gene osmads13 controls Ovule identity in rice
Plant Journal, 2007Co-Authors: Ludovico Dreni, Lucia Colombo, Sara Jacchia, Fabio Fornara, M Fornari, Pieter B F Ouwerkerk, Gynheung An, Martin M KaterAbstract:SummaryGenes that control Ovule identity were first identified in Petunia. Co-suppression of both FLORAL BINDINGPROTEIN 7 (FBP7) and FBP11, two D-lineage genes, resulted in the homeotic transformation of Ovules intocarpelloid structures. Later in Arabidopsis it was shown that three genes, SHATTERPROOF1(SHP1), SHP2,andSEEDSTICK (STK), redundantly control Ovule identity, because in the stk shp1 shp2 triple mutant Ovules loseidentity and are transformed into carpel and leaf-like structures. Of these three Arabidopsis genes STK is theonly D-lineage gene, and its expression, like FBP7 and FBP11, is restricted to Ovules. OsMADS13 is the riceortholog of STK, FBP7, and FBP11. Its amino acid sequence is similar to the Arabidopsis and Petunia proteins,and its expression is also restricted to Ovules. We show that the osmads13 mutant is female sterile and thatOvules are converted into carpelloid structures. Furthermore, making carpels inside carpels, the osmads13flower is indeterminate, showing that OsMADS13 also has a function in floral meristem determinacy.OsMADS21 is most likely to be a paralog of OsMADS13, although its expression is not restricted to Ovules.Interestingly, the osmads21 mutant did not show any obvious phenotype. Furthermore, combining theosmads13 and the osmads21 mutants did not result in any additive Ovule defect, indicating that osmads21does notcontrol Ovule identity.Theseresults suggestthat duringevolutionthe D-lineagegene OsMADS21haslost its ability to determine Ovule identity.Keywords: Ovule development, rice, redundancy, AGAMOUS subfamily, MADS-box transcription factor.IntroductionIn angiosperms Ovules develop as part of the gynoecium,which consists of one or more carpels. Megasporogenesisand megagametogenesis take place in Ovules, and afterfertilization Ovules develop into seeds. Ovule developmenthas mostly been studied in Arabidopsis thaliana, where alarge number of mutants have been described and genescontrolling Ovule development have been characterized(Skinner et al., 2004).The first two genes that control Ovule identity were iso-lated from Petunia hybrida, and have been named FLORALBINDING PROTEIN 7 (FBP7) and FBP11 (Angenent et al.,1995; Colombo et al., 1995). They both encode MIKC-typeMADS-box transcription factors, a class of transcriptionalregulators that has been shown to play key roles in thedetermination of floral organ identity in many angiospermspecies (Becker and Theissen, 2003; Gutierrez-Cortines andDavies,2000;Kateret al.,2006;Parenicovaet al.,2003).FBP7and FBP11 share 90% identity and were shown to bespecificallyexpressedinOvules.Theirconcomitantsilencingby co-suppression resulted in the homeotic transformationof Ovules into carpelloid structures, showing that they arenecessarytodetermineOvuleidentity(Angenentet al.,1995).Furthermore,ectopicexpressionofFBP7orFBP11inPetuniaresulted in the formation of Ovules on sepals and petals,suggesting that these genes are sufficient to induce Ovuledevelopment in flowers (Colombo et al., 1995).
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genetic and molecular interactions between bell1 and mads box factors support Ovule development in arabidopsis
The Plant Cell, 2007Co-Authors: Vittoria Brambilla, Martin M Kater, Raffaella Battaglia, Monica Colombo, Simona Masiero, Stefano Bencivenga, Lucia ColomboAbstract:In Arabidopsis thaliana and many other plant species, Ovules arise from carpel tissue as new meristematic formations. Cell fate in proliferating Ovule primordia is specified by particular Ovule identity factors, such as the homeodomain factor BELL1 (BEL1) and MADS box family members SEEDSTICK (STK), SHATTERPROOF1 (SHP1), SHP2, and AGAMOUS. Both in the bel1 mutant and the stk shp1 shp2 triple mutant, integuments are transformed into carpelloid structures. Combining these mutants in a bel1 stk shp1 shp2 quadruple mutant, we showed that the bel1 phenotype is significantly enhanced. We also demonstrate that Ovule differentiation requires the regulation of the stem cell maintenance gene WUSCHEL, repression of which is predominantly maintained by BEL1 during Ovule development. Based on yeast three-hybrid assays and genetic data, we show that BEL1 interacts with the Ovule identity MADS box factors when they dimerize with SEPALLATA proteins. We propose a model for Ovule development that explains how the balance between carpel identity activity and Ovule identity activity is established by a MADS box homeodomain protein complex.
