Volatile compounds are usually associated with an appearance/presence in the atmosphere. Recent advances, however, indicated that the soil is a huge reservoir and source of biogenic volatile organic ...compounds (bVOCs), which are formed from decomposing litter and dead organic material or are synthesized by underground living organism or organs and tissues of plants. This review summarizes the scarce available data on the exchange of VOCs between soil and atmosphere and the features of the soil and particle structure allowing diffusion of volatiles in the soil, which is the prerequisite for biological VOC‐based interactions. In fact, soil may function either as a sink or as a source of bVOCs. Soil VOC emissions to the atmosphere are often 1–2 (0–3) orders of magnitude lower than those from aboveground vegetation. Microorganisms and the plant root system are the major sources for bVOCs. The current methodology to detect belowground volatiles is described as well as the metabolic capabilities resulting in the wealth of microbial and root VOC emissions. Furthermore, VOC profiles are discussed as non‐destructive fingerprints for the detection of organisms. In the last chapter, belowground volatile‐based bi‐ and multi‐trophic interactions between microorganisms, plants and invertebrates in the soil are discussed.
Terpene synthases are the primary enzymes in the formation of low-molecular-weight terpene metabolites. Rapid progress in the biochemical and molecular analysis of terpene synthases has allowed ...significant investigations of their evolution, structural and mechanistic properties, and regulation. The organization of terpene synthases in large gene families, their characteristic ability to form multiple products, and their spatial and temporal regulation during development and in response to biotic and abiotic factors contribute to the time-variable formation of a diverse group of terpene metabolites. The structural diversity and complexity of terpenes generates an enormous potential for mediating plant–environment interactions. Engineering the activities of terpene synthases provides opportunities for detailed functional evaluations of terpene metabolites
in planta.
Cross-sectional study.
To document the labour market participation rate and investigate the impact of social and economic characteristics on this outcome among individuals with spinal cord injury or ...disease (SCI/D) who participated in a multidisciplinary rehabilitation programme in Brazil.
A specialised rehabilitation centre in southern Brazil.
An interview was performed with former rehabilitation clients with SCI/D. A total of 111 community-dwelling individuals with SCI/D who had been previously rehabilitated in a large regional rehabilitation centre were considered. Employment status and demographic, injury, work, and economic characteristics were self-reported via interview. Descriptive statistical analyses were performed.
The labour market participation rate was 21.6% (24 individuals). Five respondents were employed in formal work activities, and the other 19 were involved in informal activities (self-employed). Since the onset of injury, a shorter time was associated with nonparticipation in occupational work. Individuals with a higher level of education were more likely to be working. Household income was higher among the participants who had returned to work than among those who had not returned.
There is a relatively low labour market participation rate among rehabilitated individuals with SCI/D in southern Brazil. The rehabilitation services should emphasise vocational training, access to education, and employment support for individuals with SCI/D from early onset after the injury. Public policies must be revised to support labour market participation among individuals with SCI/D in Brazil.
The jasmonate family of phytohormones plays central roles in plant development and stress acclimation. However, the architecture of their signaling circuits remains largely unknown. Here we describe ...a jasmonate family binding protein, cyclophilin 20-3 (CYP20-3), which regulates stress-responsive cellular redox homeostasis. (+)-12-oxo-phytodienoic acid (OPDA) binding promotes CYP20-3 to form a complex with serine acetyltransferase 1, which triggers the formation of a hetero-oligomeric cysteine synthase complex with O -acetylserine(thiol)lyase B in chloroplasts. The cysteine synthase complex formation then activates sulfur assimilation that leads to increased levels of thiol metabolites and the buildup of cellular reduction potential. The enhanced redox capacity in turn coordinates the expression of a subset of OPDA-responsive genes. Thus, we conclude that CYP20-3 is a key effector protein that links OPDA signaling to amino acid biosynthesis and cellular redox homeostasis in stress responses.
Practical approaches to plant volatile analysis Tholl, Dorothea; Boland, Wilhelm; Hansel, Armin ...
The Plant journal : for cell and molecular biology,
February 2006, Letnik:
45, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Plants emit volatile organic compounds (VOCs) that play important roles in their interaction with the environment and have a major impact on atmospheric chemistry. The development of static and ...dynamic techniques for headspace collection of volatiles in combination with gas chromatography-mass spectrometry analysis has significantly improved our understanding of the biosynthesis and ecology of plant VOCs. Advances in automated analysis of VOCs have allowed the monitoring of fast changes in VOC emissions and facilitated in vivo studies of VOC biosynthesis. This review presents an overview of methods for the analysis of plant VOCs, including their advantages and disadvantages, with a focus on the latest technical developments. It provides guidance on how to select appropriate instrumentation and protocols for biochemical, physiological and ecologically relevant applications. These include headspace analyses of plant VOCs emitted by the whole organism, organs or enzymes as well as advanced on-line analysis methods for simultaneous measurements of VOC emissions with other physiological parameters.
Norway spruce (Picea abies L. Karst) produces an oleoresin characterized by a diverse array of terpenoids, monoterpenoids, sesquiterpenoids, and diterpene resin acids that can protect conifers ...against potential herbivores and pathogens. Oleoresin accumulates constitutively in resin ducts in the cortex and phloem (bark) of Norway spruce stems. De novo formation of traumatic resin ducts (TDs) is observed in the developing secondary xylem (wood) after insect attack, fungal elicitation, and mechanical wounding. Here, we characterize the methyl jasmonate-induced formation of TDs in Norway spruce by microscopy, chemical analyses of resin composition, and assays of terpenoid biosynthetic enzymes. The response involves tissue-specific differentiation of TDs, terpenoid accumulation, and induction of enzyme activities of both prenyltransferases and terpene synthases in the developing xylem, a tissue that constitutively lacks axial resin ducts in spruce. The induction of a complex defense response in Norway spruce by methyl jasmonate application provides new avenues to evaluate the role of resin defenses for protection of conifers against destructive pests such as white pine weevils (Pissodes strobi), bark beetles (Coleoptera, Scolytidae), and insect-associated tree pathogens.
Arabidopsis is believed to be mostly self-pollinated, although several lines of genetic and morphological evidence indicate that insect-mediated outcrossing occurs with at least a low frequency in ...wild populations. Here, we show that Arabidopsis flowers emit both monoterpenes and sesquiterpenes, potential olfactory cues for pollinating insects. Of the 32 terpene synthase genes in the Arabidopsis genome, 20 were found to be expressed in flowers, 6 of these exclusively or almost exclusively so. Two terpene synthase genes expressed exclusively in the flowers and one terpene synthase gene expressed almost exclusively in the flowers were characterized and found to encode proteins that catalyze the formation of major floral volatiles. A β-glucuronidase fusion construct with a promoter of one of these genes demonstrated that gene expression was restricted to the sepals, stigmas, anther filaments, and receptacles, reaching a peak when the stigma was receptive to cross pollen. The observation that Arabidopsis flowers synthesize and emit volatiles raises intriguing questions about the reproductive behavior of Arabidopsis in the wild and allows detailed investigations of floral volatile biosynthesis and its regulation to be performed with this model plant system.
The paper reports the results of extensive measurements and analysis of an indoor radio propagation channel's temporal variations. The empirical data base consists of 192 one-min recordings of CW ...envelope fading waveforms with both antennas stationary. Measurements were carried out in an office environment at 1100 MHz with four transmitter-receiver antenna separations of 5, 10, 20, and 30 m. Effects of controlled degrees of motion with 0, 1, 2, 3, or 4 individuals walking around the high antenna only, around the low antenna only, and around both antennas were investigated. The reported results include amplitude fading distributions, correlation properties, level crossing rates, duration of fades statistics, and spectrum widths of the frequency domain data, The results can be used in fixed wireless computer communication applications, and in supplementing the available spatial variation models of the indoor radio propagation channel.< >
Arabidopsis is emerging as a model system to study the biochemistry, biological functions, and evolution of plant terpene secondary metabolism. It was previously shown that the Arabidopsis genome ...contains over 30 genes potentially encoding terpene synthases (TPSs). Here we report the characterization of a monoterpene synthase encoded by two identical, closely linked genes, At3g25820 and At3g25830. Transcripts of these genes were detected almost exclusively in roots. An At3g25820/At3g25830 cDNA was expressed in Escherichia coli, and the protein thus produced was shown to catalyze the formation of 10 volatile monoterpenes from geranyl diphosphate, with 1,8-cineole predominating. This protein was therefore designated AtTPS-Cin. The purified recombinant AtTPS-Cin displayed similar biochemical properties to other known monoterpene synthases, except for a relatively low Km value for geranyl diphosphate of 0.2 micromolar. At3g25820/At3g25830 promoter activity, measured with a β-glucuronidase (GUS) reporter gene, was primarily found in the epidermis, cortex, and stele of mature primary and lateral roots, but not in the root meristem or the elongation zone. Although the products of AtTPS-Cin were not detected by direct extraction of plant tissue, the recent report of 1,8-cineole as an Arabidopsis root volatile (Steeghs M, Bais HP, de Gouw J, Goldan P, Kuster W, Northway M, Fall R, Vivanco JM 2004 Plant Physiol 135: 47-58) suggests that the enzyme products may be released into the rhizosphere rather than accumulated. Among Arabidopsis TPSs, AtTPS-Cin is most similar to the TPS encoded by At3g25810, a closely linked gene previously shown to be exclusively expressed in flowers. At3g25810 TPS catalyzes the formation of a set of monoterpenes that is very similar to those produced by AtTPS-Cin, but its major products are myrcene and (E)-β-ocimene, and it does not form 1,8-cineole. These data demonstrate that divergence of organ expression pattern and product specificity are ongoing processes within the Arabidopsis TPS family.
Summary
Emission of methylsalicylate (MeSA), and occasionally of methylbenzoate (MeBA), from Arabidopsis thaliana leaves was detected following the application of some forms of both biotic and ...abiotic stresses to the plant. Maximal emission of MeSA was observed following alamethicin treatment of leaves. A gene (AtBSMT1) encoding a protein with both benzoic acid (BA) and salicylic acid (SA) carboxyl methyltransferase activities was identified using a biochemical genomics approach. Its ortholog (AlBSMT1) in A. lyrata, a close relative of A. thaliana, was also isolated. The AtBSMT1 protein utilizes SA more efficiently than BA, whereas AlBSMT1 catalyzes the methylation of SA less effectively than that of BA. The AtBSMT1 and AlBSMT1 genes showed expression in leaves under normal growth conditions and were more highly expressed in the flowers. In A. thaliana leaves, the expression of AtBSMT1 was induced by alamethicin, Plutella xylostella herbivory, uprooting, physical wounding, and methyl jasmonate. SA was not an effective inducer. Using a β‐glucuronidase (GUS) reporter approach, the promoter activity of AtBSMT1 was localized to the sepals of flowers, and also to leaf trichomes and hydathodes. Upon thrip damage to leaves, AtBSMT1 promoter activity was induced specifically around the lesions.
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