P. Costantino | Università degli Studi "La Sapienza" di Roma (original) (raw)

Papers by P. Costantino

Giornale botanico italiano, 1993

BMC Plant Biology, 2015

Background: The transcription factor DOF AFFECTING GERMINATION1 (DAG1) is a repressor of the ligh... more Background: The transcription factor DOF AFFECTING GERMINATION1 (DAG1) is a repressor of the light-mediated seed germination process. DAG1 acts downstream PHYTOCHROME INTERACTING FACTOR3-LIKE 5 (PIL5), the master repressor, and negatively regulates gibberellin biosynthesis by directly repressing the biosynthetic gene AtGA3ox1. The Dof protein DOF AFFECTING GERMINATION (DAG2) shares a high degree of aminoacidic identity with DAG1. While DAG1 inactivation considerably increases the germination capability of seeds, the dag2 mutant has seeds with a germination potential substantially lower than the wild-type, indicating that these factors may play opposite roles in seed germination. Results: We show here that DAG2 expression is positively regulated by environmental factors triggering germination, whereas its expression is repressed by PIL5 and DAG1; by Chromatin Immuno Precipitation (ChIP) analysis we prove that DAG1 directly regulates DAG2. In addition, we show that Red light significantly reduces germination of dag2 mutant seeds. Conclusions: In agreement with the seed germination phenotype of the dag2 mutant previously published, the present data prove that DAG2 is a positive regulator of the light-mediated seed germination process, and particularly reveal that this protein plays its main role downstream of PIL5 and DAG1 in the phytochrome B (phyB)-mediated pathway.

The Rhizobiaceae, 1998

Virulent strains of Agrobacterium tumefaciens and Agrobacterium rhizogenes induce non-self limiti... more Virulent strains of Agrobacterium tumefaciens and Agrobacterium rhizogenes induce non-self limiting — neoplastic — growths on susceptible plants, generally in dicotyledonous species from the Angiosperms. In most cases, A. tumefaciens induces unorganized “crown gall” tumors (so named because the growths were often observed at the crown of the plant), though certain isolates can induce teratomatous tumors that exhibit a choatic array of plant structures (Figure 1). A. rhizogenes infection results in the continuous proliferation of “hairy roots” from the infection site (Figure 2). The demonstration that A. tumefaciens (then called Bacterium tumefaciens) is the causal agent of crown gall tumors was first presented by Smith and Townsend (1907) who showed that this bacterium could fulfill Koch’s postulates. Later, Riker et al. (1930) showed A. rhizogenes was, similarly, the causal agent of the hairy root disease.

The Plant Journal, 2006

The Agrobacterium rhizogenes oncogene rolB mimics the effects of auxin in that it increases the s... more The Agrobacterium rhizogenes oncogene rolB mimics the effects of auxin in that it increases the sensitivity of transformed cells to this hormone. Here we isolated a tobacco gene, ROX1, acting downstream of rolB. We show that plants with reduced levels of ROX1 mRNA, due to the expression of a 35S-driven ROX1-antisense construct, have flowers with stamens and pistils longer than normal because of an increased number of cells. Localized expression of rolB in anthers results in overexpression of ROX1 and reduced growth of stamens, due to a reduced number of cells. In addition, the longer stamens of antisense plants show a delayed xylem differentiation in the lateral bundles, primarily of the junction region between anther and filament, while the shorter stamens of ROX1-overexpressing plants show a precocious differentiation of xylem cells in the same tissues. Expression of ROX1 in stamens peaks at early stages of stamen growth, and ROX1 mRNA is localized mostly in anther procambial cells. The sequence of ROX1 shares a conserved element with a number of plant genes, including TED3, which is involved in xylem differentiation. These results point to a role of ROX1 in the balance between proliferation of procambial cells and xylem differentiation during stamen development.

Plant Physiology, 2013

Biotic and abiotic stresses limit agricultural yields, and plants are often simultaneously expose... more Biotic and abiotic stresses limit agricultural yields, and plants are often simultaneously exposed to multiple stresses. Combinations of stresses such as heat and drought or cold and high light intensity have profound effects on crop performance and yields. Thus, delineation of the regulatory networks and metabolic pathways responding to single and multiple concurrent stresses is required for breeding and engineering crop stress tolerance. Many studies have described transcriptome changes in response to single stresses. However, exposure of plants to a combination of stress factors may require agonistic or antagonistic responses or responses potentially unrelated to responses to the corresponding single stresses. To analyze such responses, we initially compared transcriptome changes in 10 Arabidopsis (Arabidopsis thaliana) ecotypes using cold, heat, high-light, salt, and flagellin treatments as single stress factors as well as their double combinations. This revealed that some 61% o...

Journal of experimental botany, 2012

The genetic basis of stem cell specification in somatic embryogenesis and organogenesis is still ... more The genetic basis of stem cell specification in somatic embryogenesis and organogenesis is still obscure. SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) genes are involved in embryogenesis and organogenesis in numerous species. In vitro culture of Cyclamen persicum immature ovules provides a system for investigating stem cell formation and maintenance, because lines forming either organs or embryos or callus without organs/embryos are available for the same cultivar and plant growth regulator conditions. The present aim was to exploit this property of cyclamen cultures to understand the role of SERK(s) in stem cell formation and maintenance in somatic embryogenesis and organogenesis in vitro, in comparison with expression in planta. CpSERK1 and CpSERK2 were isolated from embryogenic callus. CpSERK1 and CpSERK2 levels by RT-PCR showed that expression is high in embryogenic, moderate in organogenic, and null in recalcitrant calli. in situ hybridizations showed that the expression o...

Acta Endocrinologica, 1973

HeLa cell mitochondrial polysomes, estimated to consist of two to seven 60S monomers, exhibit an ... more HeLa cell mitochondrial polysomes, estimated to consist of two to seven 60S monomers, exhibit an unusual resistance to RNase and EDTA, possibly related to the strongly hydrophobic nature of their polypeptide products which makes the nascent chains particularly "sticky". Mitochondria-specific ribosomal and 4S RNA are coded for by mitochondrial DNA (mit-DNA): there is one gene for each ribosomal RNA (rRNA) species and nine genes for 4S RNA on the heavy (H) mit-DNA strand, and three 4S RNA genes on the light (L) strand. The existence of messenger RNA (mRNA) transcribed from mit-DNA is strongly suggested by the occurrence in mitochondria of poly(A) stretches, 60 to 80 residues long, most of which are covalently linked to RNA molecules coded for by mit-DNA. Mitochondrial poly(A) is not a transcription product of mit-DNA. The in vivo and in vitro products of mitochondrial protein synthesis exhibit by polyacrylamide gel electrophoresis a group of not well resolved components in t...

BMC Plant Biology, 2012

Background In crosses between the proline-deficient mutant homozygous for p5cs1 and heterozygous ... more Background In crosses between the proline-deficient mutant homozygous for p5cs1 and heterozygous for p5cs2 (p5cs1 p5cs2/P5CS2), used as male, and different Arabidopsis mutants, used as females, the p5cs2 mutant allele was rarely transmitted to the outcrossed progeny, suggesting that the fertility of the male gametophyte carrying mutations in both P5CS1 and P5CS2 is severely compromised. Results To confirm the fertility defects of pollen from p5cs1 p5cs2/P5CS2 mutants, transmission of mutant alleles through pollen was tested in two ways. First, the number of progeny inheriting a dominant sulfadiazine resistance marker linked to p5cs2 was determined. Second, the number of p5cs2/p5cs2 embryos was determined. A ratio of resistant to susceptible plantlets close to 50%, and the absence of aborted embryos were consistent with the hypothesis that the male gametophyte carrying both p5cs1 and p5cs2 alleles is rarely transmitted to the offspring. In addition, in reciprocal crosses with wild ty...

Biochemical and Biophysical Research Communications, 2003

The design of minimal units required for enzyme inhibition is a major field of interest in struct... more The design of minimal units required for enzyme inhibition is a major field of interest in structural biology and biotechnology. The successful design of the cyclic dodecapeptide corresponding to the Phe17-Val28 reactive site amino acid sequence of the low-molecular-mass trypsin inhibitor RTI-III from Brassica napus (micro-RTI-III) and of the recombinant murine dihydrofolate reductase-(DHFR-)micro-RTI-III fusion protein (DHFR-micro-RTI-III) is reported here. Micro-RTI-III was synthesized using a stepwise solid-phase approach based on the standard Fmoc chemistry, purified by RP-HPLC, and oxidatively refolded. DHFR-micro-RTI-III was expressed in Escherichia coli, purified by metal-chelate affinity chromatography, and oxidatively refolded. The affinity of micro-RTI-III for bovine trypsin (K(d)=1.6x10(-9)M) is similar to that determined for DHFR-micro-RTI-III (K(d)=6.3x10(-10)M) and native RTI-III (K(d)=2.9x10(-10)M), at pH 8.2 and 22.0 degrees C. Remarkably, micro-RTI-III protects the DHFR domain of DHFR-micro-RTI-III from trypsin digestion. Micro-RTI-III is a new minimal trypsin inhibitor and may be regarded as a tool in protein structure-function studies and for developing multifunctional and multidomain proteinase inhibitors.

Molecular Plant, 2015

Cullin-RING E3 ligases (CRLs) regulate different aspects of plant development and are activated b... more Cullin-RING E3 ligases (CRLs) regulate different aspects of plant development and are activated by modification of their cullin subunit with the ubiquitin-like protein NEDD8 (NEural precursor cell expressed Developmentally Down-regulated 8) (neddylation) and deactivated by NEDD8 removal (deneddylation). The CONSTITUTIVELY PHOTOMORPHOGENIC9 (COP9) signalosome (CSN) acts as a molecular switch of CRLs activity by reverting their neddylation status, but its contribution to embryonic and early seedling development remains poorly characterized. Here, we analyzed the phenotypic defects of csn mutants and monitored the cullin deneddylation/neddylation ratio during embryonic and early seedling development. We show that while csn mutants can complete embryogenesis (albeit at a slower pace than wildtype) and are able to germinate (albeit at a reduced rate), they progressively lose meristem activity upon germination until they become unable to sustain growth. We also show that the majority of cullin proteins are progressively neddylated during the late stages of seed maturation and become deneddylated upon seed germination. This developmentally regulated shift in the cullin neddylation status is absent in csn mutants. We conclude that the CSN and its cullin deneddylation activity are required to sustain postembryonic meristem function in Arabidopsis.

Plant Physiology, 2002

We show here that seeds from the knockout mutant of the Arabidopsis DAG1 gene encoding a Dof zinc... more We show here that seeds from the knockout mutant of the Arabidopsis DAG1 gene encoding a Dof zinc finger transcription factor have an altered response to red and far-red light. Mutant dag1 seeds are induced to germinate by much lower red light fluence rates, and germination reaches more quickly a point where it is independent of phytochrome signaling. Moreover, although microscopic analysis reveals no obvious structural alterations in the seed coat (testa) of dag1 seeds, staining assays with different dyes point to an abnormal fragility of the testa. By extensive in situ mRNA hybridization analysis we show here that the gene, which is not expressed in the embryo, is specifically expressed in the phloem of all organs of the mother plant.

Planta, Jan 5, 2016

SCARECROW controls Arabidopsis root meristem size from the root endodermis tissue by regulating t... more SCARECROW controls Arabidopsis root meristem size from the root endodermis tissue by regulating the DELLA protein RGA that in turn mediates the regulation of ARR1 levels at the transition zone. Coherent organ growth requires a fine balance between cell division and cell differentiation. Intriguingly, plants continuously develop organs post-embryonically thanks to the activity of meristems that allow growth and environmental plasticity. In Arabidopsis thaliana, continued root growth is assured when division of the distal stem cell and their daughters is balanced with cell differentiation at the meristematic transition zone (TZ). We have previously shown that at the TZ, the cytokinin-dependent transcription factor ARR1 controls the rate of differentiation commitment of meristematic cells and that its activities are coordinated with those of the distal stem cells by the gene SCARECROW (SCR). In the stem cell organizer (the quiescent center, QC), SCR directly suppresses ARR1 both sustai...

Proceedings of the National Academy of Sciences, 2001

The plant oncogene rolD stimulates the reproductive phase transition in plants. We define here th... more The plant oncogene rolD stimulates the reproductive phase transition in plants. We define here the function of its gene product. We show that the RolD protein bears sequence homology with ornithine cyclodeaminase, an uncommon enzyme of specialized-niche eubacteria and archaea that catalyzes the unusual NAD + -dependent conversion of ornithine to proline. To confirm the prediction of the bioinformatic analysis, the RolD protein was expressed in Escherichia coli and purified. An ornithine-dependent NAD + reduction that can be ascribed only to ornithine cyclodeaminase (OCD) activity was detected both in bacterial extracts containing RolD and in assays on the purified RolD protein. Furthermore, OCD activity was observed in soluble extracts from plants overexpressing rolD . The role of rolD in plant pathogenesis and its effect on plant reproductive development are discussed in light of the newly demonstrated enzymatic activity of its gene product.

Giornale botanico italiano, 1995

MGG Molecular & General Genetics, 1989

Root differentiation could be elicited on carrot discs by transformation with the agropine Ri pla... more Root differentiation could be elicited on carrot discs by transformation with the agropine Ri plasmid rolB gene cloned in the binary vector Bin19, provided two conditions were met. Firstly, an adequate auxin supply had to be provided. This was achieved by co-inoculation with a strain carrying only the auxin synthetic genes of the TR-DNA. Most of the resulting roots were

The Plant Journal, 1996

A protein which binds to the regulatory domain B necessary for expression of the plant oncogene r... more A protein which binds to the regulatory domain B necessary for expression of the plant oncogene rolB in (root) meristems contains a single zinc finger of a novel type conserved in dicots and monocots. Band shift analysis revealed the presence in tobacco nuclei of a protein selectively binding to domain B, a tetramer of which was used to isolate a cDNA (NtBBF1, Nicotiana tabacum rolB domain B Factor 1) from a tobacco expression library. The corresponding genomic clone was also isolated. The protein encoded by NtBBF1 contains a single C2C2 zinc finger, and its target sequence in domain B was identified by means of mutagenized oligonucleotides. The DNA-binding capability of the zinc finger was assessed by means of a fusion of this latter with the glutathione-S-transferase protein, that was shown to bind the same target sequence as NtBBF1. A number of other tobacco cDNAs encoding different proteins with a domain (BBF domain) encompassing the zinc finger identical to NtBBF1 were also isolated. Furthermore, a cDNA encoding a protein with an almost identical single zinc finger was isolated from Arabidopsis. A very closely related zinc finger has very recently been identified in maize transcription factors and termed the Dof domain. It is proposed that the tobacco, Arabidopsis and maize BBF/Dof domain proteins are members of a new broad family of plant transcription factors acting through a single zinc finger widely utilized in the plant kingdom.

Spectrochimica Acta Part B: Atomic Spectroscopy