RESUMEN
Two novel members of the subfamily Betarhabdovirinae, family Rhabdoviridae, were identified in Brazil. Overall, their genomes have the typical organization 3'-N-P-P3-M-G-L-5' observed in mono-segmented plant-infecting rhabdoviruses. In aristolochia-associated cytorhabdovirus (AaCV), found in the liana aristolochia (Aristolochia gibertii Hook), an additional short orphan ORF encoding a transmembrane helix was detected between P3 and M. The AaCV genome and inferred encoded proteins share the highest identity values, consistently < 60%, with their counterparts of the yerba mate chlorosis-associated virus (Cytorhabdovirus flaviyerbamate). The second virus, false jalap virus (FaJV), was detected in the herbaceous plant false jalap (Mirabilis jalapa L.) and represents together with tomato betanucleorhabdovirus 2, originally found in tomato plants in Slovenia, a tentative new species of the genus Betanucleorhabdovirus. FaJV particles accumulate in the perinuclear space, and electron-lucent viroplasms were observed in the nuclei of the infected cells. Notably, distinct from typical rhabdoviruses, most virions of AaCV were observed to be non-enclosed within membrane-bounded cavities. Instead, they were frequently seen in close association with surfaces of mitochondria or peroxisomes. Unlike FaJV, AaCV was successfully graft-transmitted to healthy plants of three species of the genus Aristolochia, while mechanical and seed transmission proved unsuccessful for both viruses. Data suggest that these viruses belong to two new tentative species within the subfamily Betarhabdovirinae.
Asunto(s)
Aristolochia , Mirabilis , Rhabdoviridae , Aristolochia/genética , Mirabilis/genética , Genoma Viral , Plantas/genética , Filogenia , Enfermedades de las PlantasRESUMEN
Endophytic bacteria play important roles in medicinal plant growth, abiotic stress, and metabolism. Mirabilis himalaica (Edgew.) Heimerl is known for its medicinal value as Tibetan traditional plant; however, little is known about the endophytic bacteria associated with this plant in different geographic conditions and vegetal tissues. To compare the endophytic bacterial community associated with this plant in different geographic conditions and vegetal tissues, we collected the leaves, stems, and roots of M. himalaica from five locations, Nongmu college (NM), Gongbujiangda (GB), Zhanang County (ZL), Lang County (LX), and Sangri County (SR), and sequenced the 16S rRNA V5-V7 region with the Illumina sequencing method. A total of 522,450 high-quality sequences and 4970 operational taxonomic units (OTUs) were obtained. The different tissues from different locations harbored unique bacterial assemblages. Proteobacteria and Actinobacteria were the dominant phyla in all the samples, while the dominant genera changed based on the different tissues. The endophytic bacterial structures in the leaf and stem tissues were different compared to root tissues. Redundancy analysis (RDA) showed that the endophytic bacterial community was significantly correlated with pH, available phosphorus (AP), total phosphorus (TP), total nitrogen (TN), and soil organic matter (SOM). These findings suggested that the geographic conditions, climate type, ecosystem type, and tissues determined the endophytic bacterial composition and relative abundances. This conclusion could facilitate an understanding of the relationship and ecological function of the endophytic bacteria associated with M. himalaica and provide valuable information for artificial planting of M. himalaica and identifying and applying functional endophytic bacteria.
Asunto(s)
Mirabilis , Plantas Medicinales , Humanos , ARN Ribosómico 16S/genética , Mirabilis/genética , Mirabilis/metabolismo , Ecosistema , Bacterias/genética , Fósforo/metabolismo , Raíces de Plantas/microbiología , Endófitos/genéticaRESUMEN
OBJECTIVES: Nepenthes belongs to the monotypic family Nepenthaceae, one of the largest carnivorous plant families. Nepenthes species show impressive adaptive radiation and suffer from being overexploited in nature. Nepenthes mirabilis is the most widely distributed species and the only Nepenthes species that is naturally distributed within China. Herein, we reported the genome and transcriptome assemblies of N. mirabilis. The assemblies will be useful resources for comparative genomics, to understand the adaptation and conservation of carnivorous species. DATA DESCRIPTION: This work produced ~ 139.5 Gb N. mirabilis whole genome sequencing reads using leaf tissues, and ~ 21.7 Gb and ~ 27.9 Gb of raw RNA-seq reads for its leaves and flowers, respectively. Transcriptome assembly obtained 339,802 transcripts, in which 79,758 open reading frames (ORFs) were identified. Function analysis indicated that these ORFs were mainly associated with proteolysis and DNA integration. The assembled genome was 691,409,685 bp with 159,555 contigs/scaffolds and an N50 of 10,307 bp. The BUSCO assessment of the assembled genome and transcriptome indicated 91.1% and 93.7% completeness, respectively. A total of 42,961 genes were predicted in the genome identified, coding for 45,461 proteins. The predicted genes were annotated using multiple databases, facilitating future functional analyses of them. This is the first genome report on the Nepenthaceae family.
Asunto(s)
Mirabilis , Transcriptoma , Transcriptoma/genética , Planta Carnívora/genética , Mirabilis/genética , GenomaRESUMEN
Here, we report the identification and characterization of four novel DNA viruses from Welwitschia mirabilis transcriptomic and genomic datasets. Complete circular virus-like sequences with affinity to members of the Caulimoviridae and Geminiviridae families were detected and characterized from Welwitschia mirabilis genomic data. The two newly members of the Caulimoviridae family have been tentatively named as Welwitschia mirabilis virus 1 and 2 (WMV1-WMV2); whereas the two identified geminiviruses were named as Welwitschia mirabilis associated geminivirus A and B (WMaGVA-WMaGVB). Phylogenetic analysis suggests that WMV1-2 belong to a proposed genus of Caulimoviridae-infecting gymnosperms. WMaGVA-B are phylogenetically related with both mastreviruses and capulaviruses and likely represent a distinct evolutionary lineage within geminiviruses. Additionally, we detected several endogenous virus-like elements (EVE) linked to the discovered viruses in the recently reported W. mirabilis genome, suggesting a shared ancient evolutionary history of these viruses and the Welwithschia.
Asunto(s)
Geminiviridae , Mirabilis , ADN , Fósiles , Geminiviridae/genética , Genoma Viral , Humanos , Mirabilis/genética , Filogenia , ViromaRESUMEN
PURPOSE: Immature Southwellina hispida (Van Cleave, 1925) Witenberg, 1932 from the body cavity of the paratenic host Gillichthys mirabilis Cooper (Gobiidae) in California are described. METHODS: New Scanning Electron images and features of micropores, hook and spine Gallium cut sections and chemistry using Energy Dispersive X-ray analysis (EDXA), and molecular profile are provided for the first time. The 18S rDNA and mt Cox1 sequences were performed for molecular and phylogenetic study. RESULTS: Our specimens were somewhat comparable to those reported from other paratenic hosts in Asia, Europe, and North and South America but varied in relative sizes of trunk and other structures, proboscis formula, and distribution of trunk spines. About 60 publications were reviewed of which one third included line drawings used for comparative morphometrics. In our specimens, the trunk measured 2.72-3.10 mm long by 0.92-1.07 mm wide and the proboscis 700-800 × 270-312 µm had 20-21 rows of 14-15 hooks each measuring 47-55 long by 12-15 µm wide at base anteriorly, 47-48 × 20-23 µm at middle bulge, and 43-50 × 13-20 µm basally. These measurements, among others were compared with measurements of juveniles from 13 other collections world-wide and intraspecific variability was noted especially in the shape of hook roots that were occasionally misinterpreted. EDXA showed hooks with high levels of Sulfur especially at the tip and edge of all hooks and low levels of Calcium and Phosphorus. Anterior spines had higher levels of Sodium but Gallium cut spine sections had higher levels of Calcium at middle and of Sulfur at base of spines. Micropores were variably distributed on the body wall and extended to the cortical layer of spines. Gene sequences of the 18S and the mitochondrial cytochrome c oxidase subunit 1 (cox 1) region were amplified for specimens of S. hispida. Molecular phylogenetic analysis inference from 18S rDNA and mt Cox1 gene sequences show a close relationship with previously reported myxozoan sequences available on GenBank database. Phylogenetic analysis positioned our S. hispida in a well-supported clade including other members of Polymorphidae. CONCLUSION: The present study combined morphological, morphometric and molecular data to identify S. hispida.
Asunto(s)
Acantocéfalos , Enfermedades de los Peces , Galio , Helmintiasis Animal , Mirabilis , Perciformes , Animales , Calcio/análisis , ADN Ribosómico/química , Microscopía Electrónica de Rastreo , Mirabilis/genética , Filogenia , Azufre/análisisRESUMEN
OBJECTIVES: Mirabilis jalapa L. and Bougainvillea spectabilis are two Mirabilis species known for their ornamental and pharmaceutical values. The organelle genomes are highly conserved with a rapid evolution rate making them suitable for evolutionary studies. Therefore, mitochondrial and chloroplast genomes of B. spectabilis and M. jalapa were sequenced to understand their evolutionary relationship with other angiosperms. DATA DESCRIPTION: Here, we report the complete mitochondrial genomes of B. spectabilis and M. jalapa (343,746 bp and 267,334 bp, respectively) and chloroplast genomes of B. spectabilis (154,520 bp) and M. jalapa (154,532 bp) obtained from Illumina NovaSeq. The mitochondrial genomes of B. spectabilis and M. jalapa consisted of 70 and 72 genes, respectively. Likewise, the chloroplast genomes of B. spectabilis and M. jalapa contained 131 and 132 genes, respectively. The generated genomic data will be useful for molecular characterization and evolutionary studies.
Asunto(s)
Genoma del Cloroplasto , Genoma Mitocondrial , Mirabilis , Nyctaginaceae , Genoma del Cloroplasto/genética , Genoma Mitocondrial/genética , Mirabilis/genética , Mitocondrias/genética , Nyctaginaceae/genéticaRESUMEN
The Synechococcales is a large cyanobacterial order comprising both unicellular and filamentous forms, with parietal thylakoid arrangement. Previously, this order has been the subject of taxonomic revisions with new families being erected. During studies of the phototrophic communities on the limestone walls of the Old Cathedral of Coimbra (UNESCO monument), a coccoid Aphanocapsa-like cyanobacterium was isolated. It was characterized using a polyphasic approach, based on morphology, 16S rRNA phylogenetic and phylogenomic analyses, internal transcribed spacer (ITS) secondary structure, and ecology. The 16S rRNA phylogenetic analyses showed that this strain is placed in a separate and highly supported family-level clade, as part of a large group comprising the families Prochlorococcaceae and Prochlorotrichaceae, with Lagosinema as the closest (although quite distant) taxon. Additionally, the phylogenomic analysis also placed this strain in a separate lineage, situated distantly apart from the family Thermosynechococcaceae, but with strains assigned to Acaryochloris marina MBIC 11017 and Aphanocapsa montana BDHKU210001 as the closest taxa. Based on these data, as well as on the results from the secondary ITS structure, morphology, and ecology, we here propose the establishment of Petrachlorosaceae fam. nov., along with the description of Petrachloros gen. nov. and Petrachloros mirabilis sp. nov. We also address additional considerations regarding some cyanobacterial taxa within the order Synechococcales, which we believe deserve further revisions.
Asunto(s)
Cianobacterias , Mirabilis , Técnicas de Tipificación Bacteriana , Cianobacterias/genética , ADN Bacteriano/genética , Ácidos Grasos , Humanos , Mirabilis/genética , Filogenia , Portugal , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , UNESCORESUMEN
The key enzymatic step in betalain biosynthesis involves conversion of l-3,4-dihydroxyphenylalanine (l-DOPA) to betalamic acid. One class of enzymes capable of this is 3,4-dihydroxyphenylalanine 4,5-dioxygenase (DODA). In betalain-producing species, multiple paralogs of this gene are maintained. This study demonstrates which paralogs function in the betalain pathway and determines the residue changes required to evolve a betalain-nonfunctional DODA into a betalain-functional DODA. Functionalities of two pairs of DODAs were tested by expression in beets, Arabidopsis and yeast, and gene silencing was performed by virus-induced gene silencing. Site-directed mutagenesis identified amino acid residues essential for betalamic acid production. Beta vulgaris and Mirabilis jalapa both possess a DODA1 lineage that functions in the betalain pathway and at least one other lineage, DODA2, that does not. Site-directed mutagenesis resulted in betalain biosynthesis by a previously nonfunctional DODA, revealing key residues required for evolution of the betalain pathway. Divergent functionality of DODA paralogs, one clade involved in betalain biosynthesis but others not, is present in various Caryophyllales species. A minimum of seven amino acid residue changes conferred betalain enzymatic activity to a betalain-nonfunctional DODA paralog, providing insight into the evolution of the betalain pigment pathway in plants.
Asunto(s)
Beta vulgaris/fisiología , Betalaínas/biosíntesis , Mutación con Ganancia de Función , Proteínas de Plantas/genética , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Betalaínas/metabolismo , Caryophyllales/genética , Dioxigenasas/genética , Dioxigenasas/metabolismo , Evolución Molecular , Regulación de la Expresión Génica de las Plantas , Levodopa/farmacocinética , Levodopa/farmacología , Mirabilis/genética , Filogenia , Pigmentación/genética , Pigmentos Biológicos/biosíntesis , Pigmentos Biológicos/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Piridinas/metabolismo , Levaduras/genéticaRESUMEN
Mirabilis himalaica (Edgew.) Heimerl is among the most important genuine medicinal plants in Tibet. However, the biosynthesis mechanisms of the active compounds in this species are unclear, severely limiting its application. To clarify the molecular biosynthesis mechanism of the key representative active compounds, specifically rotenoid, which is of special medicinal value for M. himalaica, RNA sequencing and TOF-MS technologies were used to construct transcriptomic and metabolomic libraries from the roots, stems, and leaves of M. himalaica plants collected from their natural habitat. As a result, each of the transcriptomic libraries from the different tissues was sequenced, generating more than 10 Gb of clean data ultimately assembled into 147,142 unigenes. In the three tissues, metabolomic analysis identified 522 candidate compounds, of which 170 metabolites involved in 114 metabolic pathways were mapped to the KEGG. Of these genes, 61 encoding enzymes were identified to function at key steps of the pathways related to rotenoid biosynthesis, where 14 intermediate metabolites were also located. An integrated analysis of metabolic and transcriptomic data revealed that most of the intermediate metabolites and enzymes related to rotenoid biosynthesis were synthesized in the roots, stems and leaves of M. himalaica, which suggested that the use of non-medicinal tissues to extract compounds was feasible. In addition, the CHS and CHI genes were found to play important roles in rotenoid biosynthesis, especially, since CHS might be an important rate-limiting enzyme. This study provides a hypothetical basis for the screening of new active metabolites and the metabolic engineering of rotenoid in M. himalaica.
Asunto(s)
Perfilación de la Expresión Génica/métodos , Metabolómica/métodos , Mirabilis/genética , Mirabilis/metabolismo , Flavonoides/metabolismo , Regulación de la Expresión Génica de las Plantas , Espectrometría de Masas , Redes y Vías Metabólicas , Anotación de Secuencia Molecular , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Tallos de la Planta/genética , Tallos de la Planta/metabolismo , Plantas Medicinales/genética , Plantas Medicinales/metabolismo , Análisis de Secuencia de ARNRESUMEN
Petroleum is not only an important energy resource but is also a major soil pollutant. To gain better insight into the adaptability mechanism of Mirabilis jalapa to petroleum-contaminated soil, the protein profiles of M. jalapa root were investigated using label-free quantitative proteomics technique. After exposing to petroleum-contaminated soil for 24 h, 34 proteins significantly changed their protein abundance and most of the proteins increased in protein abundance (91.18%). Combined with gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses as well as data from previous studies, our results revealed that M. jalapa enhanced tolerance to petroleum by changing antioxidation and detoxification, cell wall organization, amino acid and carbohydrate metabolism, transportation and protein process, and so on. These metabolism alterations could result in the production and secretion of low molecular carbohydrate, amino acid, and functional protein, which enhanced the bioavailability of petroleum and reducing the toxicity of the petroleum. Taken together, these results provided novel information for better understanding of the tolerance of M. jalapa to petroleum stress.
Asunto(s)
Mirabilis , Petróleo/toxicidad , Proteínas de Plantas , Proteoma , Contaminantes del Suelo/toxicidad , Mirabilis/efectos de los fármacos , Mirabilis/genética , Mirabilis/metabolismo , Mirabilis/fisiología , Proteínas de Plantas/análisis , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Raíces de Plantas/fisiología , Proteoma/efectos de los fármacos , Proteoma/metabolismo , ProteómicaRESUMEN
Welwitschia mirabilis is an ancient and rare plant distributed along the western coast of Namibia and Angola. Several aspects of Welwitschia biology and ecology have been investigated, but very little is known about the microbial communities associated with this plant. This study reports on the bacterial and fungal communities inhabiting the rhizosphere of W. mirabilis and the surrounding bulk soil. Rhizosphere communities were dominated by sequences of Alphaproteobacteria and Euromycetes, while Actinobacteria, Alphaproteobacteria, and fungi of the class Dothideomycetes jointly dominated bulk soil communities. Although microbial communities within the rhizosphere and soil samples were highly variable, very few "species" (OTUs defined at a 97% identity cut-off) were shared between these two environments. There was a small 'core' rhizosphere bacterial community (formed by Nitratireductor, Steroidobacter, Pseudonocardia and three Phylobacteriaceae) that together with Rhizophagus, an arbuscular mycorrhizal fungus, and other putative plant growth-promoting microbes may interact synergistically to promote Welwitschia growth.
Asunto(s)
Bacterias/clasificación , Fósiles/microbiología , Mirabilis/microbiología , Raíces de Plantas/microbiología , Rizosfera , Microbiología del Suelo , Suelo/química , Bacterias/genética , Mirabilis/genética , ARN Ribosómico 16S/genéticaRESUMEN
Mirabilis himalaica is an endangered medicinal plant species in the Tibetan Plateau. The two genes respectively encoding chalcone synthase (MhCHS) and chalcone isomerase (MhCHI) were isolated and characterized from M. himalaica. The sequence analysis revealed that the two genes were similar with their corresponding homologous genes in other plants. The tissue profiles showed that both MhCHS and MhCHI had higher expression levels in roots than in stems and leaves. Transgenic hairy root cultures respectively with overexpressing MhCHS and MhCHI were established. The genomic PCR detection confirmed the authority of transgenic hairy root lines, in which either MhCHS or MhCHI expression levels were much higher than that in non-transgenic hairy root line. Finally, the HPLC detection results demonstrated that the rotenoid contents in MhCHS/MhCHI-transformed hairy root lines were enhanced. This study provided two candidate genes that could be used to genetic engineering rotenoid biosynthesis in M. himalaica and an alternative method to produce rotenoid using transgenic hairy root cultures.
Asunto(s)
Aciltransferasas/genética , Liasas Intramoleculares/genética , Mirabilis/genética , Transgenes/genética , Aciltransferasas/química , Aciltransferasas/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , Liasas Intramoleculares/química , Liasas Intramoleculares/metabolismo , Mirabilis/citología , Mirabilis/enzimología , Mirabilis/metabolismo , Raíces de Plantas/metabolismo , Plantas Modificadas Genéticamente , Rotenona/metabolismo , Análisis de Secuencia de ADNRESUMEN
Betalains are tyrosine-derived red-violet and yellow pigments, found in plants only of the Caryophyllales order. Although much progress has been made in recent years in the understanding of the betalain biosynthetic process, many questions remain open with regards to several of the proposed steps in the pathway. Most conspicuous by its absence is the characterization of the first committed step in the pathway, namely the 3-hydroxylation of tyrosine to form l-3,4-dihydroxyphenylalanine (l-DOPA). We used transcriptome analysis of the betalain-producing plants red beet (Beta vulgaris) and four o'clocks (Mirabilis jalapa) to identify a novel, betalain-related cytochrome P450-type gene, CYP76AD6, and carried out gene silencing and recombinant expression assays in Nicotiana benthamiana and yeast cells to examine its functionality. l-DOPA formation in red beet was found to be redundantly catalyzed by CYP76AD6 together with a known betalain-related enzyme, CYP76AD1, which was previously thought to only catalyze a succeeding step in the pathway. While CYP76AD1 catalyzes both l-DOPA formation and its subsequent conversion to cyclo-DOPA, CYP76AD6 uniquely exhibits only tyrosine hydroxylase activity. The new findings enabled us to metabolically engineer entirely red-pigmented tobacco plants through heterologous expression of three genes taking part in the fully decoded betalain biosynthetic pathway.
Asunto(s)
Beta vulgaris/genética , Betalaínas/biosíntesis , Vías Biosintéticas , Ingeniería Genética/métodos , Mirabilis/genética , Betacianinas/biosíntesis , Betalaínas/química , Betaxantinas/biosíntesis , Vías Biosintéticas/genética , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Dihidroxifenilalanina/biosíntesis , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Silenciador del Gen , Genes de Plantas , Fenotipo , Filogenia , Pigmentación/genética , Plantas Modificadas Genéticamente , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/metabolismo , Nicotiana/genéticaRESUMEN
The variegated flower colors of many plant species have been shown to result from the insertion or excision of transposable elements into genes that encode enzymes involved in anthocyanin synthesis. To date, however, it has not been established whether this phenomenon is responsible for the variegation produced by other pigments such as betalains. During betalain synthesis in red beet, the enzyme CYP76AD1 catalyzes the conversion of L-dihydroxyphenylalanine (DOPA) to cyclo-DOPA. RNA sequencing (RNA-seq) analysis indicated that the homologous gene in four o'clock (Mirabilis jalapa) is CYP76AD3. Here, we show that in four o'clock with red perianths, the CYP76AD3 gene consists of one intron and two exons; however, in a mutant with a perianth showing red variegation on a yellow background, a transposable element, dTmj1, had been excised from the intron. This is the first report that a transposition event affecting a gene encoding an enzyme for betalain synthesis can result in a variegated flower phenotype.
Asunto(s)
Betalaínas/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Flores/enzimología , Regulación de la Expresión Génica de las Plantas , Mirabilis/enzimología , Betacianinas/análisis , Betacianinas/metabolismo , Betalaínas/análisis , Betaxantinas/análisis , Betaxantinas/metabolismo , Vías Biosintéticas , Sistema Enzimático del Citocromo P-450/metabolismo , Elementos Transponibles de ADN , Dihidroxifenilalanina/metabolismo , Exones , Flores/anatomía & histología , Flores/química , Flores/genética , Intrones , Mirabilis/anatomía & histología , Mirabilis/química , Mirabilis/genética , Mutagénesis Insercional , Fenotipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Análisis de Secuencia de ARNRESUMEN
Some molecular aspects of flower senescence have been reviewed. The isolation, identification and characterization of different genes from various flowers (mainly from petals) associated with senescence have been discussed. The isolated genes were divided into different groups. A large proportion of genes have been found to be upregulated during flower senescence while some genes were also found to be downregulated indicating that there exists a complex interplay between the expression patterns of various genes. The genes involved in petal expansion are found to be upregulated during normal flower development from anthesis to open flower stage, but XTH (Xyloglucan endotransglucosylase hydrolase) is found to be involved in petal expansion as well as abscission. Cysteine proteases or the genes encoding cysteine proteases (assigned a central role in protein degradation) have been identified from various flower systems, but no cysteine protease has been identified from senescing Mirabilis jalapa flowers. In addition to proteases, the genes encoding ubiquitin (exhibiting proteasomal degradation by 26S proteasomes) have also been identified suggesting the two alternate pathways for protein degradation. Genes encoding specific nucleases have also been identified, but they displayed an early increase in transcript abundance before the senescence symptoms become evident and characterize the involvement of PCD during flower senescence. A range of transcription factors are described and their possible role in flower senescence has been discussed. A detailed description of genes involved in ethylene synthesis and the components involved in ethylene signaling have been presented.
Asunto(s)
Etilenos/metabolismo , Flores/genética , Magnoliopsida/genética , Reguladores del Crecimiento de las Plantas/metabolismo , Proteínas de Plantas/genética , Transducción de Señal , Apoptosis , Pared Celular/metabolismo , Proteasas de Cisteína/genética , Flores/fisiología , Regulación de la Expresión Génica de las Plantas , Magnoliopsida/fisiología , Mirabilis/genética , Mirabilis/fisiología , Modelos Biológicos , Receptores de Superficie Celular/genética , Factores de TiempoRESUMEN
Betalains are synthesized in flowers, fruits and other tissues of the plant order Caryophyllales. Betalamic acid is the chromophore of betalain pigments synthesized by a ring-cleaving enzyme reaction on l-dihydroxyphenylalanine (DOPA). Although reverse genetic evidence has proven that DOPA 4,5-dioxygenase (DOD) is a key enzyme of betalain biosynthesis, all attempts to detect recombinant plant DOD activity in vitro have failed. Here, we report on the formation of betalamic acid from DOPA under suitable assay conditions using recombinant MjDOD produced by Escherichia coli. This is the first report showing biochemical evidence for DOD activity in vitro.
Asunto(s)
Betalaínas/metabolismo , Mirabilis/enzimología , Oxigenasas/metabolismo , Proteínas de Plantas/metabolismo , Piridinas/metabolismo , Clonación Molecular , ADN Complementario/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Regulación de la Expresión Génica de las Plantas , Mirabilis/genética , Datos de Secuencia Molecular , Oxigenasas/genética , Proteínas de Plantas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMEN
A modest ethylene climacteric accompanies flower senescence in Mirabilis jalapa L., and exogenous ethylene accelerates the process. However, inhibitors of ethylene action and synthesis have little effect on the life-span of these ephemeral flowers. Treatment with alpha-amanitin, an inhibitor of DNA-dependent RNA synthesis, substantially delays the onset of senescence. This effect falls linearly between 7 h and 8 h after the start of flower opening. Subtractive hybridization was used to isolate transcripts that were up- and down-regulated during this critical period. Eighty-two up-regulated and 65 down-regulated transcripts were isolated. The genes identified encode homologues of a range of transcription factors, and of proteins involved in protein turnover and degradation. Real-time quantitative RT-PCR was used to examine expression patterns of these genes during flower opening and senescence. Genes that were identified as being down-regulated during senescence showed a common pattern of very high expression during floral opening. These genes included a homologue of CCA1, a 'clock' gene identified in Arabidopsis thaliana and an aspartyl protease. Up-regulated genes commonly showed a pattern of increase during the critical period (4-9 h after opening), and some showed very strong up-regulation. For example, the abundance of transcripts encoding a RING zinc finger protein increased >40 000 fold during the critical period.
Asunto(s)
Senescencia Celular/genética , Mirabilis/crecimiento & desarrollo , Proteínas de Plantas/fisiología , Amanitinas/farmacología , Senescencia Celular/efectos de los fármacos , Etilenos/antagonistas & inhibidores , Etilenos/farmacología , Flores/efectos de los fármacos , Flores/genética , Flores/crecimiento & desarrollo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Mirabilis/efectos de los fármacos , Mirabilis/genética , Hibridación de Ácido Nucleico , Reguladores del Crecimiento de las Plantas/farmacología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
To understand how auxin regulates sensitivity of abscission zone (AZ) tissues to ethylene, we used a polymerase chain reaction-based subtractive approach to identify gene transcripts in Mirabilis jalapa AZs that changed in abundance during the time the zones became competent to abscise in response to exogenous ethylene. Transcript expression was then examined in leaf and stem AZs over the period they became ethylene competent following indole-3-acetic acid (IAA) depletion either by leaf deblading, treatment with the IAA transport inhibitor naphthylphthalamic acid, or cutting the stem above a node (decapitation). Transcripts down-regulated by deblading/decapitation included Mj-Aux/IAA1 and Mj-Aux/IAA2, encoding Aux/IAA proteins, and three other transcripts showing highest identity to a polygalacturonase inhibitor protein, a beta-expansin, and a beta-tubulin. Application of IAA to the cut end of petioles or stumps inhibited abscission, and prevented the decline in the levels of transcripts in both AZs. Transcripts up-regulated in the AZ following deblading/decapitation or treatment with naphthylphthalamic acid were isolated from plants pretreated with 1-methylcyclopropene before deblading to help select against ethylene-induced genes. Some of the up-regulated transcripts showed identity to proteins associated with ethylene or stress responses, while others did not show homology to known sequences. Sucrose infiltration of stem stumps enhanced abscission following ethylene treatment and also enhanced the induction of some of the up-regulated genes. Our results demonstrate a correlation between acquisition of competence to respond to ethylene in both leaf and stem AZs, and decline in abundance of auxin regulatory gene transcripts.
Asunto(s)
Ácidos Indolacéticos/metabolismo , Mirabilis/crecimiento & desarrollo , Etilenos/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Ácidos Indolacéticos/farmacología , Mirabilis/genética , Mirabilis/metabolismo , Datos de Secuencia Molecular , Ftalimidas/farmacología , Reguladores del Crecimiento de las Plantas/metabolismo , Reguladores del Crecimiento de las Plantas/farmacología , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Tallos de la Planta/efectos de los fármacos , Tallos de la Planta/crecimiento & desarrollo , Tallos de la Planta/metabolismo , Reacción en Cadena de la Polimerasa , ARN Mensajero/análisis , ARN Mensajero/metabolismoRESUMEN
Genes coding for an iris ribosomal-inactivating protein (I-RIP), a maize beta-glucanase (M-GLU), and a Mirabilis jalapa antimicrobial peptide (Mj-AMP1) were separately introduced into tomato (Lycopersicon esculentum cv. Sweet Chelsea) cotyledons via Agrobacterium tumefaciens-mediated transformation. Transgenic lines carrying each of the transgenes were confirmed for integration into the tomato genome using Southern blot hybridization. Transcription of I-RIP, M-GLU, and Mj-AMP1 genes in various transgenic lines was determined using Northern blot analysis. Plants of selected transgenic lines were inoculated with a 2-3x10(4) conidial spores/ml suspension of the fungal pathogen Alternaria solani, the causal agent of tomato early blight. Compared to control (non-transformed) plants, two transgenic lines carrying either a M-GLU or Mj-AMP1 showed enhanced resistance to early blight disease. None of the four lines carrying the I-RIP transgene showed increased resistance to early blight.
Asunto(s)
Genes de Plantas , Enfermedades de las Plantas/genética , Solanum lycopersicum/genética , Agrobacterium tumefaciens/genética , Alternaria/patogenicidad , Expresión Génica , Glicósido Hidrolasas/genética , Género Iris/genética , Solanum lycopersicum/microbiología , Mirabilis/genética , N-Glicosil Hidrolasas/genética , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Proteínas Inactivadoras de Ribosomas Tipo 1 , Transformación Genética , Zea mays/enzimología , Zea mays/genéticaRESUMEN
cDNAs encoding an enzyme with UDP-glucose:cyclo-DOPA 5-O-glucosyltransferase activity were isolated from four o'clocks and feather cockscombs. Phylogenetic analysis of the amino acid sequences deduced from the cDNAs show that they represent a single subclade distinct from those of other phenylpropanoid and flavonoid glucosyltransferases. Changes in the amount of transcripts of the cDNA in four o'clocks correlated with the accumulation of betanin during flower development. The cDNAs isolated here were candidates for the gene of the enzyme involved in another pathway of betacyanin biosynthesis via glucosylation at the cyclo-DOPA step rather than at the betanidin step.