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At least 379 records · Page 21Linked to original sources
PubMed2006

Tête à tête inside a plant cell: establishing compatibility between plants and biotrophic fungi and oomycetes.

'Compatibility' describes the complementary relationship between a plant species and an adapted pathogen species that underlies susceptibility and which ultimately results in disease. Owing to elaborate surveillance systems and defence mechanisms on the plant side and a common lack of adaptation of many microbial pathogens, resistance is the rule and compatibility the exception for most plant-microbe combinations. While there has been major scientific interest in 'resistance' in the past decade, which has revealed many of its underlying molecular components, the analysis of 'compatibility', although intimately intertwined with 'resistance', has not been pursued with a similar intensity. Various recent studies, however, provide a first glimpse of the pivotal players and potential molecular mechanisms essential for compatibility in both the plant and parasite partners. In this review we highlight these findings with a particular emphasis on obligate biotrophic and hemibiotrophic fungal and oomycete pathogens and discuss novel strategies that might help to uncover further the molecular principles underlying compatibility to these highly specialized pathogens.

Fungi↗
PubMed2026

Plant species identification by genome skimming across the vascular plant tree of life.

Accurate species identification is essential for biodiversity conservation and sustainable use, yet standard plant DNA barcoding often fails to achieve species-level resolution. We present a large-scale empirical evaluation of genome skimming as a tool to improve plant species discrimination. Using standardised data from 1969 individuals representing 475 species from 32 genera across major lineages of the vascular plant tree of life, we compare conventional plastid + internal transcribed spacer (ITS) barcodes with genome skimming approaches. Standard barcoding using rbcL, matK, trnH-psbA and ITS resolved about half of species (49.3%), with six genera showing <&#x2009;25% species discrimination. By contrast, genome skimming enabled the recovery of complete plastid genomes, yielding 57.6% species discrimination. It also generated sufficient nuclear genomic data for additional resolution from k-mer analysis, achieving 66.8% species discrimination - an average gain of 17.5% over standard barcodes - while eliminating cases of extreme failure (<&#x2009;25% resolution). The recovery of complete plastomes and ribosomal DNAs from genome skims also ensures backward compatibility with existing barcode datasets. Our results demonstrate that genome skimming provides data that substantially improves species-level resolution across diverse plant lineages and offers a scalable, high-throughput approach for building comprehensive reference resources to support global biodiversity initiatives.

DNA Barcoding, Taxonomic↗
PubMed2006

Human impacts, plant invasion, and imperiled plant species in California.

Invasive species are one of the fastest growing conservation problems. These species homogenize the world's flora and fauna, threaten rare and endemic species, and impose large economic costs. Here, we examine the distribution of 834 of the more than 1000 exotic plant taxa that have become established in California, USA. Total species richness increases with net primary productivity; however, the exotic flora is richest in low-lying coastal sites that harbor large numbers of imperiled species, while native diversity is highest in areas with high mean elevation. Weedy and invasive exotics are more tightly linked to the distribution of imperiled species than the overall pool of exotic species. Structural equation modeling suggests that while human activities, such as urbanization and agriculture, facilitate the initial invasion by exotic plants, exotics spread ahead of the front of human development into areas with high numbers of threatened native plants. The range sizes of exotic taxa are an order of magnitude smaller than for comparable native taxa. The current small range size of exotic species implies that California has a significant "invasion debt" that will be paid as exotic plants expand their range and spread throughout the state.

California↗
PubMed1991

On the trail of a new regulatory system in plants. Polyomines as modulators of plant development sponsored by Fundación Juan March, Madrid, Spain, February 4-6, 1991.

Investigations into the physiology and biochemistry of polyamines in plants have virtually exploded in the last decade. While not yet accepted by plant physiologists as plant hormones or even as major regulators of plant growth and development, the polyamines require consideration in such varied fields as cell division, organ differentiation, senescence, and stress. We are sure to see more conferences on this subject in the near future.

Adaptation, Physiological↗
PubMed1984

Mycoplasma-like organisms (MLO), pathogens of the plant yellows diseases, as a model of coevolution between prokaryotes, insects and plants.

There is no satisfactory theory to explain how parasites whose effect is to kill or to weaken their hosts have been able to survive evolution. A good explanation may be found in the study of mycoplasma-like organisms (MLO). We show here the existence of natural cycles of MLO between symptomless wild plants and unaffected vectors. Such natural cycles may be the basis of a coevolutionary process by which the prokaryotes and the whole cycle have persisted to our time. Disease outbreaks occur with intrusion of a cultivated plant (direct mode) or an imported insect (indirect mode). From an evolutionary point of view, the natural cycle constitutes a protection for the host plants and natural vectors against the introduction of foreign plants or vectors as competitors in their ecological niche. A role of MLO and other parasites in evolution could be to provide stability to ecosystems, which is necessary for new characters to emerge.

Animals↗
PubMed1998

[Genetic transformation of plants, recombination processes, and gene expression regulation in transgenic plants].

Recent studies in molecular biology and gene engineering were conducive to accumulation of numerous facts which help better understand the processes of plant genome functioning and follow up the effects of recombination processes in purposefully modified genome of a transformed plant on its expression. This review analyzes the major approaches to studies and results attained in plant gene engineering and plant genome imprinting.

DNA Methylation↗
PubMed2001

Epigenetic developmental mechanisms in plants: molecules and targets of plant epigenetic regulation.

Genetic approaches to understanding the role of epigenetic regulation of gene expression in plants and its mechanisms have revealed several new components. Rapidly accumulating information from other eukaryotes provides complementary knowledge with important implications for plant research. Comparison of epigenetic events across species is proving critical for defining the mechanisms and functions of epigenetic modification, including those specific to plants.

Chromatin↗
PubMed2002

CpR18, a novel SAP-domain plant transcription factor, binds to a promoter region necessary for ABA mediated expression of the CDeT27-45 gene from the resurrection plant Craterostigma plantagineum Hochst.

CDeT27-45 is a lea-like gene from the resurrection plant Craterostigma plantagineum (Scrophulariaceae) which is strongly expressed in vegetative tissues in response to dehydration or treatment with abscisic acid (ABA). Expression of the gene is correlated with the acquisition of desiccation tolerance. Nuclear proteins bind to a 29-bp cis-regulatory region of the promoter which is essential for transcriptional activation of the CDeT27-45 gene by ABA. Using a yeast one-hybrid screen, the cDNA clone CpR18 was isolated, which encodes a protein with specific binding activity for the cis-regulatory element in the CDeT27-45 promoter. The protein contains an acidic region, a SAP-domain, a zinc finger of the C3H-type, and two motifs which are conserved in proteins from several plant species. One of the conserved regions is rich in basic residues and is predicted to form a helix-loop-helix structure. The R18 gene shows high similarities to genomic sequences and ESTs from other plant species. The tissue-specific expression pattern of the rare R18 mRNA and the distribution of nuclear protein binding activity for the CDeT27-45 promoter fragment are compared. The R18 protein is indeed localized in the nucleus, and activates transcription of CDeT27-45 promoter-GUS fusion constructs in tobacco protoplasts. DNA blot analysis and isolation of genomic clones reveal that two copies of R18 are present in the C. plantagineum genome.

Abscisic Acid↗
PubMed2006

Changing green leaf volatile biosynthesis in plants: an approach for improving plant resistance against both herbivores and pathogens.

Green leaf volatiles (GLVs) are commonly emitted by green plants, and their production is drastically enhanced when they are under biotic stress. To clarify the ecological function of naturally emitted GLVs, we studied the response of Arabidopsis, whose GLV biosynthesis had been modified, when subjected to herbivory or a pathogenic infection. There was a significant increase in GLV production after herbivory by cabbage white butterfly larvae and pathogen (gray mold) infection in hydroperoxide lyase (HPL) sense Arabidopsis compared with WT controls. The HPL sense modification resulted in the plant being more attractive to the parasitic wasp Cotesia glomerata, leading to higher mortality of the herbivores. The HPL sense modification also resulted in greater inhibition of growth of the fungus. By contrast, HPL antisense Arabidopsis produced fewer GLVs, attracted fewer parasitoids, and was more susceptible to the pathogens than the WT control. These data show that (i) one of the ecological functions of GLV biosynthesis related to resistance against both herbivores and pathogens, and (ii) the genetic modification of GLV biosynthesis could be a unique approach for improving plant resistance against such biotic stresses.

Aldehyde-Lyases↗
PubMed2002

Constitutive expression of the beta-ketothiolase gene in transgenic plants. A major obstacle for obtaining polyhydroxybutyrate-producing plants.

Polyhydroxybutyrate (PHB) is a member of a class of thermoelastic polymers called polyhydroxyalkanoates that serve many bacteria as intracellular storage molecules for carbon and energy. Transgenic plants provide a potential means of producing this polymer cost-effectively. To date, however, few reports of the successful production of this polymer have been published, with the exception of work with transgenic Arabidopsis. Using a variety of chimeric constructs, we have determined that the constitutive, chloroplast-localized expression of one of the genes involved in PHB production-the beta-ketothiolase (phbA) gene-is detrimental to the efficient production of transgenic PHB. The alternate use of either inducible or somatically activated promoters allowed the construction of transgenic PHB-producing potato (Solanum tuberosum) and tobacco (Nicotiana tabacum) plants, although the amount of PHB formed was still rather low. Taking advantage of an inducible promoter, the maximal amount of PHB produced in transgenic potato was 0.09 mg g(-1) dry weight. In transgenic tobacco using a somatically activated promoter, up to 3.2 mg g(-1) dry weight was accumulated. In Arabidopsis, the formation of high levels of PHB had previously been shown to be accompanied by severe negative effects on growth and development of the plant. Phasins are proteins known from PHB-producing bacteria speculated to serve as protectants against the highly hydrophobic surface of the PHB granules in the bacterial intracellular milieu. Co-expression of the phasin gene in parallel with the PHB synthesis genes, however, did not lead to reduced symptom development.

Acetyl-CoA C-Acyltransferase↗
PubMed1994

The C3 plant Flaveria pringlei contains a plastidic NADP-malic enzyme which is orthologous to the C4 isoform of the C4 plant F. trinervia.

To study the molecular evolution of NADP-dependent malic enzyme (NADP-ME) in the genus Flaveria a leaf-specific cDNA library of the C3 plant F. pringlei was screened for the presence of sequences homologous to the C4 isoform gene (named modA) of the C4 plant F. trinervia. The cDNAs isolated contained varying numbers of identical restriction fragments suggesting that they were derived from a single gene. This was supported by Southern hybridisation experiments with genomic DNA from F. trinervia and F. pringlei. Nucleotide sequence analysis of a full-size clone identified the presence of a typical plastidic transit peptide and revealed that the mature modA proteins of F. trinervia (C4) and F. pringlei (C3) are 90% similar. These findings indicate that C3 plants, like C4 species, possess a plastidic isoform of NADP-ME and that the modA genes of the two species represent orthologous genes. Northern analyses showed that modA transcripts accumulate to similar levels in leaves, stems and roots of F. pringlei. The expression of this gene in F. pringlei thus appears to be rather constitutive. In contrast, the modA gene of F. trinervia is abundantly expressed in leaves, but maintains its expression in stems and roots. It has to be concluded from these data that the leaf-specific increase in the expression level was a key step which was taken during the evolution of the C4 isoform modA gene starting from a C3 ancestral gene.

Amino Acid Sequence↗
PubMed1993

Immunodetection of the plum pox virus helper component in infected plants and expression of its gene in transgenic plants.

Tobacco plants (Nicotiana tabacum cv. Xanthi) have been transformed via Agrobacterium tumefaciens vectors, with cDNAs corresponding to the plum pox virus (PPV) cistron 2 encoding helper component (HC-Pro) and with the first two and half cistrons of the PPV genome. Presence of the HC-Pro in PPV-infected plants and transgenic plants transformed with the gene coding for this protein was investigated using specific polyclonal antibodies produced against the PPV HC-Pro. The results suggest that two proteases are involved in the processing of the PPV N-terminal polyprotein to yield a protein of 48 k (HC-Pro). HC-Pro autolytically cleaves at its carboxyl-terminus and a proteolytic activity, probably associated with the protein (P1) encoded by the cistron 1, is required for the cleavage in planta between the proteins derived from cistrons 1 and 2.

Agrobacterium tumefaciens↗
PubMed2006

Rapid plant regeneration and analysis of genetic fidelity of in vitro derived plants of Chlorophytum arundinaceum Baker--an endangered medicinal herb.

An efficient in vitro multiplication system via multiple shoot bud induction and regeneration has been developed in Chlorophytum arundinaceum using shoot crown explants. Optimum regeneration frequency (87%) and desirable organogenetic response in the form of de novo organized multiple shoot buds without an intervening callus phase was obtained on Murashige and Skoog's (MS) minimal organics medium containing 3% sucrose (w/v) supplemented with 4 x 10(-6) M Kn and 2 x 10(-6) MIBA. Axenic secondary explants with multiple shoot buds on subculturing elicited best response with 1 x 10(-5) M Kinetin (Kn) and 5 x 10(-6) M indole-3-butyric acid (IBA) giving rise to an average of 18.74 shoots per culture with mean shoot length of 7.6 cm +/- 1.73. Varying molar ratios of either Kn/IBA or Kn/NAA revealed statistically significant differences in the regeneration frequencies among the phytohormone treatments. It was observed that the shoot bud differentiation and regeneration was influenced by the molar ratios of cytokinins/auxin rather than their relative concentrations. Healthy regenerated shoots were rooted in half strength MS basal medium containing 3% sucrose (w/v) supplemented with 5 x 10(-6) M IBA. Following simple hardening procedures, rooted plantlets, were transferred to soil-sand (1:1; v/v) with more than 90% success. Genetic fidelity was assessed using random amplified polymorphic DNA (RAPD), karyotype analysis and meiotic behaviour of in vitro and in vivo plants. Five arbitrary decamers displayed same banding profile within all the micropropagated plants and in vivo explant donor. The cytological and molecular analysis complemented and compared well and showed no genomic alterations in the plants regenerated through shoot bud differentiation. High multiplication frequency, molecular, cytological and phenotypic stability ensures the efficacy of the protocol developed for the production and conservation of this important endangered medicinal herb.

Asparagaceae↗
PubMed2002

Phytochemicals in plants: genomics-assisted plant improvement for nutritional and health benefits.

Plants are an important source of essential nutrients and health-beneficial components that are crucial for human life. Because the intake of these phytochemicals is not always adequate, the resources of plant biotechnology are being used to enhance the nutritional quality of our plant-based food supply. Various improvement strategies are feasible, depending on whether the phytochemical target is a major or minor constituent. Recent efforts in gene discovery and functional genomics are providing the necessary understanding to develop and evaluate different approaches to manipulate phytochemical composition.

Diet↗
PubMed2000

The plantibody approach: expression of antibody genes in plants to modulate plant metabolism or to obtain pathogen resistance.

Immunomodulation is a molecular technique that allows the interference with cellular metabolism or pathogen infectivity by the ectopic expression of genes encoding antibodies or antibody fragments. In recent years, several reports have proven the value of this tool in plant research for modulation of phytohormone activity and for blocking plant-pathogen infection. Efficient application of the plantibody approach requires different levels of investigation. First of all, methods have to be available to clone efficiently the genes coding for antibodies or antibody fragments that bind the target antigen. Secondly, conditions to obtain high accumulation of antigen-binding antibodies and antibody fragments in plants are being investigated and optimized. Thirdly, different strategies are being evaluated to interfere with the function of the target molecule, thus enabling immunomodulation of metabolism or pathogen infectivity. In the near future, optimized antibody gene isolation and expression, especially in reducing subcellular environments, such as the cytosol and nucleus, should turn immunomodulation into a powerful and attractive tool for gene inactivation, complementary to the classical antisense and co-suppression approaches.

Antibodies↗
PubMed1964

HISTAMINE PROTECTION PRODUCED BY PLANT TUMOUR EXTRACTS. THE ACTIVE PRINCIPLE OF TOMATO PLANTS INFECTED WITH GROWN-GALL.

Guinea-pigs were protected against the lethal effects of a histamine aerosol by intraperitoneal injection of stable extracts of normal tomato plants and of tomato plants infected with crown-gall tumours. The protection was short-lasting. No difference was observed between the activities of extracts of normal and of infected plants. The active principle of the extracts was isolated, and identified as the steroid alkaloid glycoside, tomatine.

Alkaloids↗
PubMed2006

A new approach for in vitro regeneration of tomato plants devoid of exogenous plant growth hormones.

Many available methodologies for in vitro regeneration of commercial tomato varieties promote not only the production of normal shoots but also individual leaves, shoots without apical meristems and vitrified structures. All these abnormal formations influence and diminish the regeneration efficiency. At the basis of this phenomenon lies callus development. We optimized an alternative procedure by which the regeneration occurs without abnormal shoot formation. The portion including the proximal part of hypocotyls and the radicle was cultured on medium consisting of Murashige and Skoog salts, 4 mg/L thiamine, 100 mg/L mio-inositol and 3% sucrose. After two-three weeks, 60% explants showed adventitious shoot formation. No changes in the morphological characteristics of regenerated plants and fruits were observed as compared with parents. Karyotypic analysis of regenerated plants showed no variations in chromosome number. The optimized procedure offers the advantage of tomato plant regeneration avoiding callus formation, which enables normal plant recovery with an efficiency ranging from 1.45 +/- 0.05 to 2.57 +/- 0.06 shoots per explant in Campbell-28, Amalia, Lignon, and Floradel cultivars.

Agriculture↗
PubMed1993

Inventory of plants used in traditional medicine in Somalia. IV. Plants of the families Passifloraceae-Zygophyllaceae.

Thirty-seven plants are listed, which are used by traditional healers in the central and southern parts of Somalia. For each species are listed: the botanical name with synonyms, collection number, vernacular name, medicinal use, preparation of remedy and dosage. Results of a literature survey are also reported including medicinal use, substances isolated and pharmacological effects. Three plants which should have been included in Part I of the series have been added and some corrections to that paper have been made. With these additions the series comprises 180 different plant species, distributed in 59 plant families.

Animals↗