44 research outputs found
ROLE OF THE ALOG GENE FAMILY IN THE INFLORESCENCE DEVELOPMENT OF ORYZA SATIVA AND ARABIDOPSIS THALIANA
No full textHuman population growth makes it of primary importance to find new ways to sustainably increase agricultural crop production to meet the increasing food demand. In this context, inflorescence architecture is one of the key agronomical traits which determines grain yield; thus, it has been a major target for crop domestication and improvement. For example, in rice an increased number of branches allows the panicle to bear more seeds, leading to a higher yield.
To study the molecular genetic processes that lead to inflorescence architecture establishment, we used two model plant species: Oryza sativa, model plant for monocotyledons, and Arabidopsis thaliana, model plant for dicotyledons. In both Arabidopsis and rice, inflorescence architecture development depends on a complex gene regulatory network that controls the identity and activity of the reproductive meristems.
A substantial number of genes involved in the pathways that lead to inflorescence architecture development have been identified, however, this complex developmental process is still far from understood. To identify new players involved in panicle development, reproductive meristems of Arabidopsis and rice were isolated by laser microdissection at different stages of development and used for RNA-seq analysis. The analysis of differentially expressed genes between the various stages of meristem development showed that several members of the ALOG (Arabidopsis LIGHT-DEPENDENT SHORT HYPOCOTYL 1 and Oryza G1) gene family showed the same expression pattern in meristematic tissues, suggesting a possible role in the determination of inflorescence architecture. These genes are OsG1L1, OsG1L2 and TAW1/OsG1L5 of rice; and AtLSH1, AtLSH3 and AtLSH4 of Arabidopsis.
One member of the rice ALOG gene family, TAW1/OsG1L5, was already shown to be a fundamental regulator of inflorescence development in rice (Yoshida et al., 2013), further suggesting an important role for the ALOG gene family in reproductive development.
My Ph.D. research project was focused on elucidating the role of the ALOG genes in inflorescence development in both Arabidopsis and rice.
We generated single and multiple mutants in both species using CRISPR-Cas9. The molecular and morphological analysis of the mutants revealed that the knock-out of these genes determined defects in plant inflorescence architecture linked to the process of identity acquisition of the reproductive meristems
Crop Reproductive Meristems in the Genomic Era: A Brief Overview
No full textModulation of traits beneficial for cultivation and yield is one of the main goals of crop improvement. One of the targets for enhancing productivity is changing the architecture of inflorescences since in many species it determines fruit and seed yield. Inflorescence shape and organization is genetically established during the early stages of reproductive development and depends on the number, arrangement, activities, and duration of meristems during the reproductive phase of the plant life cycle. Despite the variety of inflorescence architectures observable in nature, many key aspects of inflorescence development are conserved among different species. For instance, the genetic network in charge of specifying the identity of the different reproductive meristems, which can be indeterminate or determinate, seems to be similar among distantly related species. The availability of a large number of published transcriptomic datasets for plants with different inflorescence architectures, allowed us to identify transcription factor gene families that are differentially expressed in determinate and indeterminate reproductive meristems. The data that we review here for Arabidopsis, rice, barley, wheat, and maize, particularly deepens our knowledge of their involvement in meristem identity specification
Assessing the role of REM13, REM34 and REM46 during the transition to the reproductive phase in Arabidopsis thaliana
No full textREM (reproductive meristem) transcription factors have been proposed as regulators of plant reproductive development mainly based on their specific expression patterns in reproductive structures, but their roles are still largely unknown probably because of their redundancy. We selected three REM genes (REM13, REM34 and REM46) for functional analysis, based on their genome position and/or co-expression data. Our results suggest that these genes have a role in flowering time regulation and may modulate cell cycle progression. In addition, protein interaction experiments revealed that REM34 and REM46 interact with each other, suggesting that they might work cooperatively to regulate cell division during inflorescence meristem commitment. Previous attempts of using co-expression data as a guide for functional analysis of REMs were limited by the transcriptomic data available at the time. Our results uncover previously unknown functions of three members of the REM family of Arabidopsis thaliana and open the door to more comprehensive studies of the REM family, where the combination of co-expression analysis followed by functional studies might contribute to uncovering the biological roles of these proteins and the relationship among them
Assessing Changes in Root Architecture, Developmental Timing, Transcriptional and Hormonal Profiles in Rice Co-Cultivated with Azolla filiculoides
No full textStrategies for increasing rice yield are needed to keep pace with the expected global population growth and sustainably address the challenges posed by climate change. In Southeast Asian countries, rice farming benefits from the use of Azolla spp. for nitrogen supply. By virtue of their symbiosis with the nitrogen-fixing cyanobacterium Trichormus azollae, Azolla spp. are ferns that release nitrogen into the environment upon biomass decomposition. However, whether and to what extent actively growing Azolla plants influence the development of co-cultivated rice seedlings remains unclear. To address this, rice (Oryza sativa L. var. Kitaake) seedlings were co-cultivated hydroponically with Azolla filiculoides for up to two months. Morphological changes in rice roots and aerial organs were assessed alongside nitric oxide assays in rice roots, root transcriptomics, and targeted hormonomics of rice roots, leaves, and growth media. Here, we showed that co-cultivation with actively growing A. filiculoides alters rice root architecture by inducing a nitric oxide boost and accelerates leaf and tiller differentiation and proliferation. Overall, this study provides an in-depth analysis of the morphogenetic effects of co-cultivated A. filiculoides on rice during early vegetative growth. It also paves the way for studies assessing whether A. filiculoides co-cultivation primes rice plants to better withstand abiotic and biotic stresses
Short vegetative phase reduces gibberellin biosynthesis at the arabidopsis shoot apex to regulate the floral transition
No full textIn Arabidopsis thaliana environmental and endogenous cues promote flowering by activating expression of a small number of integrator genes. The MADS box transcription factor SHORT VEGETATIVE PHASE (SVP) is a critical inhibitor of flowering that directly represses transcription of these genes. However, we show by genetic analysis that the effect of SVP cannot be fully explained by repressing known floral integrator genes. To identify additional SVP functions, we analyzed genome-wide transcriptome data and show that GIBBERELLIN 20 OXIDASE 2, which encodes an enzyme required for biosynthesis of the growth regulator gibberellin (GA), is upregulated in svp mutants. GA is known to promote flowering, and we find that svp mutants contain elevated levels of GA that correlate with GA-related phenotypes such as early flowering and organ elongation. The ga20ox2 mutation suppresses the elevated GA levels and partially suppresses the growth and early flowering phenotypes of svp mutants. In wild-type plants, SVP expression in the shoot apical meristem falls when plants are exposed to photoperiods that induce flowering, and this correlates with increased expression of GA20ox2. Mutations that impair the photoperiodic flowering pathway prevent this downregulation of SVP and the strong increase in expression of GA20ox2. We conclude that SVP delays flowering by repressing GA biosynthesis as well as integrator gene expression and that, in response to inductive photoperiods, repression of SVP contributes to the rise in GA at the shoot apex, promoting rapid induction of flowering.Fil: Andrés, Fernando. Max Planck Institute for Plant Breeding Research; AlemaniaFil: Porri, Aimone. Max Planck Institute for Plant Breeding Research; AlemaniaFil: Torti, Stefano. Max Planck Institute for Plant Breeding Research; AlemaniaFil: Mateos, Julieta Lisa. Max Planck Institute for Plant Breeding Research; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; Argentina. Fundación Instituto Leloir; ArgentinaFil: Romera Branchat, Maida. Max Planck Institute for Plant Breeding Research; AlemaniaFil: García Martínez, José Luis. Universidad Politécnica
de Valencia. Instituto de Biología Molecular y Celular de Plantas; EspañaFil: Fornara, Fabio. Università degli Studi di Milano. Department of Bioscience; Italia. Max Planck Institute for Plant Breeding Research; AlemaniaFil: Gregis, Veronica. Università degli Studi di Milano. Department of Bioscience; ItaliaFil: Kater, Martin M.. Università degli Studi di Milano. Department of Bioscience; ItaliaFil: Coupland, George. Max Planck Institute for Plant Breeding Research; Alemani
Uncovering genetic and molecular interactions among floral meristem identity genes in Arabidopsis thaliana
No full textBPC transcription factors and a Polycomb Group protein confine the expression of the ovule identity gene SEEDSTICK in Arabidodpsis
No full textThe BASIC PENTACYSTEINE (BPC) GAGA (C-box) binding proteins belong to a small plant transcription factor family. We previously reported that BPCs of class I bind directly to C-boxes in the SEEDSTICK (STK) promoter and the mutagenesis of these cis-elements affects STK expression in the flower. The MADS-domain factor SHORT VEGETATIVE PHASE (SVP) is another key regulator of STK. Direct binding of SVP to CArG-boxes in the STK promoter are required to repress its expression during the first stages of flower development. Here we show that BPCs of class II directly interact with SVP and that MADS-domain binding sites in the STK promoter region are important for the correct spatial and temporal expression of this homeotic gene. Furthermore, we show that BPCs of class I and II act redundantly to repress STK expression in the flower, most likely by recruiting TERMINAL FLOWER 2/LIKE HETEROCHROMATIN PROTEIN 1 (TFL2/LHP1) and mediating the establishment and the maintenance of H3K27me3 repressive marks on the DNA. We investigate the role of LHP1 in the regulation of STK expression. Besides providing a better understanding of the role of BPC transcription factors in the regulation of STK expression, our results suggest the existence of a more general regulatory complex composed of BPCs, MADS-domain factors and PRCs, that cooperate to regulate gene expression in reproductive tissues. We believe that our data along with the molecular model herein described could provide significant insights for a more comprehensive understanding of gene regulation in plants
Molecular mechanisms of BASIC PENTACYSTEINE PROTEINS (BPCs) and the MADS-box factor SVP in the regulation of homeotic genes in Arabidopsis
No full textThe Arabidopsis transcription factor BPCs family is composed of seven members divided into three classes, based on their protein sequence similarity. BPCs bind the regulatory sequence of the homeotic gene SEEDSTICK (STK) promoter together with the MADS-box factor SHORT VEGETATIVE PHASE (SVP) . We show that MADS-box binding sites on the STK promoter region are necessary for STK correct spatial expression. To study the contribution of BPCs of class II to the regulation of the homeotic gene we generated the quintuple bpc12346 mutant. Through ChIP experiments, we found that SVP binds the genomic region of STK even in the absence of BPCs, whereas BPCs need SVP for the binding of the STK promoter. Besides, BPCs mutations affect STK expression in the flower. Moreover we analyzed the repressive trimethylation mark at Lys-27 in histone H3 in STK regulatory regions and we found that it’s reduced in bpc12346 mutant suggesting a direct role of chromatin modification in the regulation of STK expression mediated by BPCs. Our results provide insights into the molecular mechanisms that drive transcription regulation in plants and investigate the involvement of a protein complex in which BPCs and MADS-box might cooperate to regulate the expression of homeotic genes during development
The SVP transcription factor coordinates GA biosynthesis with floral induction during photoperiodic flowering
No full textThe timing of flowering is crucial in determining the final production of seeds and fruits. In plants the transition from vegetative growth to flowering is regulated by several environmental stimuli and by the age of the individual. This complexity is conferred by a network of genetic pathways that has been characterized best in the model species Arabidopsis thaliana. FLOWERING LOCUS T (FT) is a positive regulator of flowering which participates in different genetic pathways, such as vernalisation, thermosensory, gibberellin (GA) and potoperiod. In Arabidopsis, FT is induced by long days and has been placed at the core of the photoperiodic pathway, downstream of the GIGANTEA (GI) and CONSTANS (CO) genes. Under LDs, FT protein is transported from the leaves to the shoot apical meristem (SAM) where it induces the expression of several floral promoter genes (reviewed in Andrés and Coupland (2012)). Interestingly, recent studies have shown that GA also induces flowering at the SAM under LDs and plays an important role in the FT-mediated transcriptional activation of floral promoter genes. However, how the photoperiod and the GA signaling pathways are coordinated at the SAM to promote flowering is still unclear. The Arabidopsis MADS-box gene SHORT VEGETATIVE PHASE (SVP) is a well-known floral repressor which mRNA expression is reduced in the SAM by the action of the photoperiod signals, mainly represented by FT protein. We have performed ChIP-seq and expression analysis which resulted in the identification of genes and pathways regulated by SVP (Gregis et al., 2013). These analyses revealed an unexpected role of SVP in regulating components of different hormonal biosynthetic and signaling pathways, such as cytokinin and GA pathways. Remarkably, we found that the expression of GA20ox2, a gene encoding a rate-limiting enzyme in GA biosynthesis, is repressed by SVP. Up-regulation of GA20ox2 mRNA in the svp-41 mutant leads to elevated levels of GA that correlate with GA-related phenotypes such as early flowering and organ elongation (Andrés et al, submitted). Taking our results together, we propose that inductive LD conditions contribute to the reduction of SVP expression in the shoot apex which in turn, allows the de-repression of the gibberellin pathway and therefore accelerates the floral transition process
Metropoly and Metropolitan Bishop in legal perspective – nowadays and in the past (on 20th anniversary of establishing Białystok Metropoly)
No full textKs. Wojciech GóralskiThe subject of the thesis is the institution of a metropoly (a church district)
and the authority governing the metropolitan territorial unit in the historical
and legal perspective. After presenting the genesis and beginnings of forming
of the metropoly in ancient times, the author describes its further, dynamic development
in medieval decretals. Next, the author focuses on a reform carried
out by the Trent Council (1545-1563) and analyses its reformation decretals. In
the following part of the thesis the author discusses relevant provisions of the
Canon Law of 1917. Finally, he reviews the directive of the Council of Vatican II
(1962-1965) and provisions of the Canon Law of 1983, in which previous provisions
have been largely simplified. Documents of the Holy See issued while
this Canonic Law was in force (Exhortation of John Paul II Pastores gregis of 16
October 2003 and documents of the Directory of Congregation for Bishops
Apostolorum successores of 22 February 2004) have also been considered.
Having analysed provisions of the Canon Law of 1983 and the above successive
documents regarding the metropoly and the office of the metropolitan
bishop over the ages, on one hand, a fidelity to centuries-old tradition can be observed, but on the other hand, perceiving the institution of the metropoly
in a more pastoral perspective meeting requirements of modern times.Uniwersytet Kardynała Stefana Wyszyńskiego w Warszawie11/212114
