Radiocarbon Flux Measurements Provide Insight into Why a Pyroligneous Acid Product Stimulates Plant Growth.

Agriculture in the 21st century faces many formidable challenges with the growing global population. Increasing demands on the planet's natural resources already tax existing agricultural practices. Today, many farmers are using biochemical treatments to improve their yields.

Radiocarbon Flux Measurements Reveal Mechanistic Insight into Heat-Stress Induction of Nicotine Biosynthesis in .

The effect of high-temperature (HT) stress on nicotine biosynthesis in was examined. Nicotine content was measured in mature leaves, young sink leaves, and in roots from well-watered plants grown at 25 °C as controls and from plants exposed to 38 °C and 43 °C temperatures applied for 24, 48, 72, and 96 h duration. At 38 °C, all leaf nicotine levels were significantly less than control plants for up to 72 h exposure but rose sharply thereafter to levels significantly greater than controls with 96 h exposure.

Studies Using Mutant Strains of Reveal That Atmospheric Nitrogen Fixation and Auxin Production Are Light Dependent Processes.

As the use of microbial inoculants in agriculture rises, it becomes important to understand how the environment may influence microbial ability to promote plant growth. This work examines whether there are light dependencies in the biological functions of , a commercialized prolific grass-root colonizer. Though classically defined as non-phototrophic, possesses photoreceptors that could perceive light conducted through its host's roots.

Plants Utilize Suberin Biopolymers as a Vector for Transmitting Visible Light through Their Roots.

Plants conduct light from their aboveground tissues belowground to their root system. This phenomenon may influence root growth and perhaps serve to stimulate natural biological functions of the microorganisms associating with them. Here we show that light transmission in maize roots largely occurs within the endodermis, a region rich in suberin polyester biopolymers.

Treatments with Liquid Smoke and Certain Chemical Constituents Prevalent in Smoke Reduce Phloem Vascular Sectoriality in the Sunflower with Improvement to Growth.

Many higher plants possess a physiological organization that is based upon the carbon economy of their parts. While photosynthates are partitioned according to the relative strength of the plant's sink tissues, in many species there is also a very close relationship between partitioning, phyllotaxy and vascular connectivity giving rise to sectorial patterns of allocation. Here, we examined the influence of smoke and certain chemical constituents prevalent in smoke including, catechol, resorcinol and hydroquinone on phloem vascular sectoriality in common sunflower ( L.

Bacteria Promotes Mn Uptake in Maize with Benefits to Leaf Photosynthesis.

is a prolific grass-root colonizing bacteria well-known for its ability to promote plant growth in several cereal crops. Here we show that one of the mechanisms of action in boosting plant performance is through increased assimilation of the micronutrient manganese by the host. Using radioactive Mn (t 5.

Examining effects of rhizobacteria in relieving abiotic crop stresses using carbon-11 radiotracing.

In agriculture, plant growth promoting bacteria (PGPB) are increasingly used for reducing environmental stress-related crop losses through mutualistic actions of these microorganisms, activating physiological and biochemical responses, building tolerances within their hosts. Here we report the use of radioactive carbon-11 (t 20.4 min) to examine the metabolic and physiological responses of Zea mays to Azospirillum brasilense (HM053) inoculation while plants were subjected to salinity and low nitrogen stresses.

Carbon-11 Radiotracing Reveals Physiological and Metabolic Responses of Maize Grown under Different Regimes of Boron Treatment.

In agriculture, boron is known to play a critical role in healthy plant growth. To dissect the role of boron in maize metabolism, radioactive carbon-11 (t 20.4 min) was used to examine the physiological and metabolic responses of 3-week-old B73 maize plants to different levels of boron spanning 0 mM, 0.

Examining the Effects of the Nitrogen Environment on Growth and N-Fixation of Endophytic in Maize Seedlings by Applying C Radiotracing.

as an endophyte and prolific root colonizer of numerous cereal crops, occupies an important ecological niche in agriculture because of its ability to promote plant growth and potentially improve crop yield. More importantly, there exists the untapped potential to harness its ability, as a diazotroph, to fix atmospheric N as an alternative nitrogen resource to synthetic fertilizers. While mechanisms for plant growth promotion remain controversial, especially in cereal crops, one irrefutable fact is these microorganisms rely heavily on plant-borne carbon as their main energy source in support of their own growth and biological functions.

Plant-Growth-Promoting Bacteria Can Impact Zinc Uptake in : An Examination of the Mechanisms of Action Using Functional Mutants of .

Among the PGPB, the genus -with an emphasis on -is likely the most studied microorganism for mitigation of plant stress. Here, we report the investigation of functional mutants HM053, and FP10 of to understand how the biological functions of these microorganisms can affect host Zn uptake. HM053 is a constitutively expressed strain that hyper-fixes N and produces high levels of the plant's relevant hormone auxin.

From the Outside in: An Overview of Positron Imaging of Plant and Soil Processes.

Positron-emitting nuclides have long been used as imaging agents in medical science to spatially trace processes non-invasively, allowing for real-time molecular imaging using low tracer concentrations. This ability to non-destructively visualize processes in real time also makes positron imaging uniquely suitable for probing various processes in plants and porous environmental media, such as soils and sediments. Here, we provide an overview of historical and current applications of positron imaging in environmental research.

Defense Priming in Accelerates and Amplifies 'New' C/N Fluxes in Key Amino Acid Biosynthetic Pathways.

In the struggle to survive herbivory by leaf-feeding insects, plants employ multiple strategies to defend themselves. One mechanism by which plants increase resistance is by intensifying their responsiveness in the production of certain defense agents to create a rapid response. Known as defense priming, this action can accelerate and amplify responses of metabolic pathways, providing plants with long-lasting resistance, especially when faced with waves of attack.

Quantifying Plant-Borne Carbon Assimilation by Root-Associating Bacteria.

is a rhizobacteria that occupies a specialized ecological niche in agriculture. As an endophyte and prolific grass root colonizer it has the potential to promote plant growth, enhancing crop yield in many cereal crops. While the mechanisms for plant growth promotion are controversial, the one irrefutable fact is these microorganisms rely heavily on plant-borne carbon as their main energy source in support of their biological functions.

Assessment of a F-Phenylboronic Acid Radiotracer for Imaging Boron in Maize.

Boron (B) is an essential plant micronutrient. Deficiencies of B have drastic consequences on plant development leading to crop yield losses and reductions in root and shoot growth. Understanding the molecular and cellular consequences of B deficiency is challenging, partly because of the limited availability of B imaging techniques.

Detecting Rapid Changes in Carbon Transport and Partitioning with Carbon-11 (C).

Noninvasive techniques to measure phloem transport of carbon will be crucial to efforts to engineer improved crop yields, which are highly dependent on carbon partitioning. Phloem, which is buried in the interior of the plant, is highly sensitive to tissue damage. Here we describe nondestructive methods using carbon-11, fed to leaves as CO, as a tracer to track export of recently fixed carbon from leaves, transport speed through the phloem, and distribution or partitioning throughout the plant.

Synthesis of l-[4- C]Asparagine by Ring-Opening Nucleophilic C-Cyanation Reaction of a Chiral Cyclic Sulfamidate Precursor.

The development of a convenient and rapid method to synthesize radiolabeled, enantiomerically pure amino acids (AAs) as potential positron emission tomography (PET) imaging agents for mapping various biochemical transformations in living organisms remains a challenge. This is especially true for the synthesis of carbon-11-labeled AAs given the short half-life of carbon-11 ( C, t =20.4 min).

Diurnal cycling of rhizosphere bacterial communities is associated with shifts in carbon metabolism.

Background: The circadian clock regulates plant metabolic functions and is an important component in plant health and productivity. Rhizosphere bacteria play critical roles in plant growth, health, and development and are shaped primarily by soil communities. Using Illumina next-generation sequencing and high-resolution mass spectrometry, we characterized bacterial communities of wild-type (Col-0) Arabidopsis thaliana and an acyclic line (OX34) ectopically expressing the circadian clock-associated cca1 transcription factor, relative to a soil control, to determine how cycling dynamics affected the microbial community.

In vivo quantitative imaging of photoassimilate transport dynamics and allocation in large plants using a commercial positron emission tomography (PET) scanner.

Background: Although important aspects of whole-plant carbon allocation in crop plants (e.g., to grain) occur late in development when the plants are large, techniques to study carbon transport and allocation processes have not been adapted for large plants.

Robust biological nitrogen fixation in a model grass-bacterial association.

Nitrogen-fixing rhizobacteria can promote plant growth; however, it is controversial whether biological nitrogen fixation (BNF) from associative interaction contributes to growth promotion. The roots of Setaria viridis, a model C4 grass, were effectively colonized by bacterial inoculants resulting in a significant enhancement of growth. Nitrogen-13 tracer studies provided direct evidence for tracer uptake by the host plant and incorporation into protein.

The design and performance of a portable handheld (11)CO2 delivery system.

We constructed a hand-held device to efficiently trap [(11)C]CO2 from the cyclotron target, safely transport up to 3.7GBq (100mCi) doses to remote sites and release it without the need for a liquid cryogen. The system consists of a 180W furnace and a miniature molecular sieve trap (80-100mg; 80-100mesh 13×) placed inside a lead pig weighing 11.

Radiosynthesis of 3-indolyl[1-¹¹C]acetic acid for phyto-PET-imaging: an improved production procedure and formulation method.

An improved production procedure and formulation method for the carbon-11 radiolabeled phytohormone, 3-indolyl-[l-(11)C]acetic acid ([(11)C]IAA), was developed by modifying selected original reaction parameters. This updated procedure both doubled the yield (from 25.9±6.

Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms.

Upon attack by leaf herbivores, many plants reallocate photoassimilates below ground. However, little is known about how plants respond when the roots themselves come under attack. We investigated induced resource allocation in maize plants that are infested by the larvae Western corn rootworm Diabrotica virgifera virgifera.

Temporal changes in allocation and partitioning of new carbon as (11)C elicited by simulated herbivory suggest that roots shape aboveground responses in Arabidopsis.

Using the short-lived isotope (11)C (t(1/2) = 20.4 min) as (11)CO(2), we captured temporal changes in whole-plant carbon movement and partitioning of recently fixed carbon into primary and secondary metabolites in a time course (2, 6, and 24 h) following simulated herbivory with the well-known defense elicitor methyl jasmonate (MeJA) to young leaves of Arabidopsis (Arabidopsis thaliana). Both (11)CO(2) fixation and (11)C-photosynthate export from the labeled source leaf increased rapidly (2 h) following MeJA treatment relative to controls, with preferential allocation of radiolabeled resources belowground.

Novel application of 2-[(18)F]fluoro-2-deoxy-D-glucose to study plant defenses.

Introduction: Since its first use in humans in 1976, 2-[¹⁸F]fluoro-2-deoxy-d-glucose (¹⁸FDG) continues to serve as a tracer to measure tissue glucose metabolism in medical imaging. Here we demonstrate a novel use for this tracer to study glycoside biosynthesis in plants as a measure of plant response to defense induction.

Methods: Coupling autoradiography with radio high-performance liquid chromatography analysis of tissue extracts, we examined the combined effects of leaf wounding and treatment using the potent plant defense hormone, methyl jasmonate (MeJA), to measure tracer distribution and tracer use in secondary defense chemistry in Arabidopsis thaliana.