Suchergebnisse

Our atmosphere, water resources and soil are becoming increasingly contaminated with inorganic and organic compounds as a result of anthropogenic-driven inputs, mainly from industry, mining, motorized traffic, agriculture, logging and military actions. Alleviation and prevention of environmental pollution can be achieved by utilization of plants and their associated microbes. Recent advances in plant-microbe interaction research revealed that plants are able to shape their rhizosphere microbiome through active secretion of substrates that are known to vary between plant species. Soil-borne microorganisms such as actinobacteria, algae, protozoa and different types of bacteria having different capabilities of functional activities can vary extensively in soils and occur in associations in the rhizosphere of plants. Microbial associations are known to affect mobility and availability of substances to the plant through the release of chelating agents, acidification, phosphate solubilization and redox changes and exudates derived from the plant can help to stimulate the survival and action of these microorganisms. A broad knowledge about the mechanisms in plants for the uptake, translocation, storage, and detoxification of contaminants, and interactions between plants and microorganisms are critical in developing technologies and best management practices for environmental clean-up. A comprehensive understanding of interactions between plants and rhizospheric microorganisms in the rhizosphere and plant-based processes will provide new opportunities to develop more efficient plants and better management practices for removal of contaminants. This chapter reviews plant-microbe interactions in phytoremediation with particular reference to the microbial dynamics in the rhizosphere of plants growing on contaminated soils.

11 páginas, 3 tablas, 5 figuras ; Root functional diversity of submerged vegetation exerts a major effect on nitrogen (N) cycling in lake sediments. This fact, however, is neglected in current N-balance models because the links between the engineering role of plants and in situ microbial N cycling are poorly understood. We hypothesized that macrophyte species with high root oxygen loss (ROL) capacity promote the highest denitrification because of a higher abundance of ammonia oxidizers and tighter coupling between nitrifiers and denitrifier communities. We sampled five small ultraoligotrophic shallow lakes with abundant macrophyte cover including sediments dominated either by Isoetes spp. (high ROL), mixed communities of natopotamids (low ROL), and unvegetated sandy sediments. At each site, we quantified denitrification (DNT) rates and proxies for the abundance of denitrifiers (nirS and nirK genes), and both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) and the diversity of nirS-harboring bacteria. Vegetated sediments showed significantly higher abundances of N-cycling genes than bare sediments. Plant communities dominated by Isoetes generated sediments with higher redox and NO2 3 concentrations and significantly higher DNT rates than natopotamidsdominated landscapes. Accordingly, increasing DNT rates were observed along the gradient from low ROL plants-bare sediments-high ROL plants. Significantly higher abundance of the archaeal amoA gene was recorded in sediments colonized by high ROL plants unveiling a key biogeochemical role for AOA in coupling macrophyte landscape and ecosystem denitrification. ; MVC was supported by a Juan de la Cierva fellowship from the Spanish Office for Research (MINECO) and a Beatriu de Pin os from the Catalan Government. This research was granted by projects DARKNESS CGL2012-32747 (MINECO) to EOC and AQUAREST (OAPN 212/2010) to EG. EC, EOC and EG are members of the Environmental Changes Ecology Group (GECA), an Excellence Research Group (SGRDGR), of the Generalitat de Catalunya (Ref. 2014 SGR 1249. 2014–2017). ; Peer reviewed

The root lesion nematode Pratylenchus penetrans is a migratory species that attacks a broad range of crops. Like other plant pathogens, P. penetrans deploys a battery of secreted protein effectors to manipulate plant hosts and induce disease. Although several candidate effectors of P. penetrans have been identified, detailed mechanisms of their functions and particularly their host targets remain largely unexplored. In this study, a repertoire of candidate genes encoding pioneer effectors of P. penetrans was amplified from mixed life stages of the nematode, and candidate effectors were cloned and subjected to transient expression in a heterologous host, Nicotiana benthamiana, using potato virus X-based gene vector. Among seven analyzed genes, the candidate effector designated as Ppen10370 triggered pleiotropic phenotypes substantially different from those produced by wild type infection. Transcriptome analysis of plants expressing Ppen10370 demonstrated that observed phenotypic changes were likely related to disruption of core biological processes in the plant due to effector-originated activities. Cross-species comparative analysis of Ppen10370 identified homolog gene sequences in five other Pratylenchus species, and their transcripts were found to be localized specifically in the nematode esophageal glands by in situ hybridization. RNA silencing of the Ppen10370 resulted in a significant reduction of nematode reproduction and development, demonstrating an important role of the esophageal gland effector for parasitism. ; United States Department of Agriculture Agricultural Research Service CRIS project [804221000-300-00D]; Fundacao para a Ciencia e a Tecnologia (FCT, Foundation for Science and Technology) [UIDB/05183/2020, PTDC/AGR-PRO/2589/2014]; FCT postdoctoral fellowship [SFRH/BPD/116030/2016] ; Published version ; This project was supported by the United States Department of Agriculture Agricultural Research Service CRIS project number 804221000-300-00D, by the National Funds through Fundacao para a Ciencia e a Tecnologia (FCT, Foundation for Science and Technology) under the projects UIDB/05183/2020 and PTDC/AGR-PRO/2589/2014 (to M. Mota and J. Branco) and by a FCT postdoctoral fellowship SFRH/BPD/116030/2016 (to C. S. L. Vicente). ; Public domain authored by a U.S. government employee

A 'box-in-box' cocultivation system was used to investigate plant responses to microbial volatile compounds (VCs) and to evaluate the contributions of organic and inorganic VCs (VOCs and VICs, respectively) to these responses. Arabidopsis plants were exposed to VCs emitted by adjacent Alternaria alternata and Penicillium aurantiogriseum cultures, with and without charcoal filtration. No VOCs were detected in the headspace of growth chambers containing fungal cultures with charcoal filters. However, these growth chambers exhibited elevated CO2 and bioactive CO and NO headspace concentrations. Independently of charcoal filtration, VCs from both fungal phytopathogens promoted growth and distinct developmental changes. Plants cultured at CO2 levels observed in growth boxes containing fungal cultures were identical to those cultured at ambient CO2. Plants exposed to charcoal-filtered fungal VCs, nonfiltered VCs, or superelevated CO2 levels exhibited transcriptional changes resembling those induced by increased irradiance. Thus, in the 'box-in-box'' system, (a) fungal VICs other than CO2 and/or VOCs not detected by our analytical systems strongly influence the plants' responses to fungal VCs, (b) different microorganisms release VCs with distinct action potentials, (c) transcriptional changes in VC-exposed plants are mainly due to enhanced photosynthesis signaling, and (d) regulation of some plant responses to fungal VCs is primarily posttranscriptional. ; Comisión Interministerial de Ciencia y Tecnología and Fondo Europeo de Desarrollo Regional, Grant/Award Numbers: BIO2013-49125-C2-1-P, BIO2016-78747-P and BIO2013-49125-C2-1-; Government of Navarra, Grant/Award Numbers: P1044 AGROESTI and P1004 PROMEBIO

A "box‐in‐box" cocultivation system was used to investigate plant responses to microbial volatile compounds (VCs) and to evaluate the contributions of organic and inorganic VCs (VOCs and VICs, respectively) to these responses. Arabidopsis plants were exposed to VCs emitted by adjacent Alternaria alternata and Penicillium aurantiogriseum cultures, with and without charcoal filtration. No VOCs were detected in the headspace of growth chambers containing fungal cultures with charcoal filters. However, these growth chambers exhibited elevated CO2 and bioactive CO and NO headspace concentrations. Independently of charcoal filtration, VCs from both fungal phytopathogens promoted growth and distinct developmental changes. Plants cultured at CO2 levels observed in growth boxes containing fungal cultures were identical to those cultured at ambient CO2. Plants exposed to charcoal‐filtered fungal VCs, nonfiltered VCs, or superelevated CO2 levels exhibited transcriptional changes resembling those induced by increased irradiance. Thus, in the "box‐in‐box" system, (a) fungal VICs other than CO2 and/or VOCs not detected by our analytical systems strongly influence the plants' responses to fungal VCs, (b) different microorganisms release VCs with distinct action potentials, (c) transcriptional changes in VC‐exposed plants are mainly due to enhanced photosynthesis signaling, and (d) regulation of some plant responses to fungal VCs is primarily posttranscriptional. ; This work was partially supported by the Comisión Interministerial de Ciencia y Tecnología and Fondo Europeo de Desarrollo Regional (Spain; grants BIO2013‐49125‐C2‐1‐P and BIO2016‐78747‐P) and the Government of Navarra (refs. P1044 AGROESTI and P1004 PROMEBIO). ; Peer reviewed

Engieered Nanoparticles (ENPs) in Agricultural Revolution: An Enticing Domain to Move Carefully -- Nanotechnology: Advancement for Agricultural Sustainability -- Nanotechnology for sustainable crop production: recent development and strategies -- Interaction of Titanium dioxide nanoparticles with Plants in Agroecosystems -- Interaction of nano-TiO2 with plants: Preparation and translocation -- Plant physiological responses to engineered nanoparticles -- Engineered nanoparticles in agro-ecosystems: implications on the soil health -- Effect of engineered nanoparticles on soil attributes and potential in reclamation of degraded lands -- Advances of Engineered Nanofertilizers for Modern Agriculture -- Nano-fertilizers and Nano-pesticides as Promoters of Plant Growth in Agriculture -- Bio-nanosensors: Synthesis and their substantial role in agriculture.

1 Introduction -- 1A General remarks -- 1B Classification of organisms -- 1C Lipid nomenclature -- 2 Major Lipid Types in Plants and Micro-Organisms -- 2A Fatty acids -- 2B Acyl lipids -- 2C Terpenoids -- 2D Sterols -- 2E Other lipid types -- 2F Ether lipids -- 3 Distribution of Lipids -- 3A Lipid distributions in different organisms and their use in taxonomy -- 3B Subcellular distribution of lipids -- 3C Intramembrane lipid distribution -- 3D Subcellular fractionation and membrane isolation -- 3E Factors affecting the lipid composition of plants and microorganisms -- 4 Biosynthesis -- 4A Fatty acids -- 4B Acyl lipids -- 4C Terpenoids and steroids -- 4D Complex lipids -- 4E Ether lipids -- 5 Degradation -- 5A Degradation of acyl lipids -- 5B Oxidation of fatty acids -- 6 Lipid Functions -- 6A Membrane structure and function -- 6B Storage -- 6C Microbial lipids as virulence factors -- 6D Conclusion -- Further reading.

1.4 Changes in Vm, Ca2+ influx and reactive oxygen intermediate generation are early cellular events induced in plants by insect feeding1.5 Shared signal transduction components in microbe and insect elicitor perception; 1.6 Regulation of phytohormone accumulation and signalling during insect feeding; 1.6.1 Jasmonic acid; 1.6.2 Ethylene; 1.6.3 Salicylic acid; 1.7 Interconnection of the phytohormone system in plants; 1.8 Conclusions and perspectives; Acknowledgements; References; 2 Herbivore Oral Secretions are the First Line of Protection Against Plant-Induced Defences; 2.1 Introduction.