Chitosan is a natural elicitor, used for stimulating plant growth and inducing plant defense. However, due to difficulty in monitoring root growth and activity, the effects of chitosan treatment on plant root systems have been less studied as compared to plant shoot parts that include leaves, seeds, and fruits. This results in an indefinite outcome of the benefits of chitosan on plant roots. Therefore, this review aims to evaluate the effects of chitosan treatment on root growth and defense responses based on current evidence. Interestingly, many studies have demonstrated that chitosan can induce plant root defense systems, yet conversely inhibiting root growth. The effects were most clearly observed from studies using liquid or solid media as substrates, while the results from the studies using soil were inconclusive and require additional investigation to observe the effects of environmental factors. In addition, root chitosan treatment showed variable effects on shoot growth, where low chitosan concentrations tend to promote shoot growth, but high chitosan concentrations may affect shoot development. Additionally, this review discusses the potential methods of chitosan application onto plant roots. Water insolubility of chitosan is likely a major issue for root treatment. Chitosan can be dissolved in acids, but this could induce acidity stress in plant roots. Modified versions of chitosan, such as chitosan nanoparticles, carboxylated chitosan, and graft chitosan copolymers have been developed to improve solubility and functionality. Chitosan nanoparticles can also be used to encapsulate other biocontrol agents to augment biological effects on plant defense. In conclusion, root chitosan treatment could help to promote plant defense and prevent root infections, abating the uses of chemical fungicides in agriculture. However, further research is required to monitor the impact of root chitosan treatment on long-term plant growth in order to gain multifaceted information to maximize the effectiveness of root chitosan application.

Purpose This study aims to uses biosocial gender theory to describe successful entrepreneurial behavior in conflict zones. Specifically, the authors investigate how the reliance on agentic (assertive, individual focused) behavior and communal (facilitative and friendly) behavior lead to differential outcomes depending on the physical gender of the entrepreneur exhibiting the behavior. Design/methodology/approach The authors developed a conceptual framework based on extant literature. To test the framework, the authors gathered survey data from Iraqi-Kurdish entrepreneurs who have been living in a state of war since the late 1980s and use a novel analytical method to deal with the limitations inherent in gathering survey data in conflict zones. Qualitative data is presented to generate a better understanding of the survey results. Findings The findings indicate females who are successful in taking on the traditional male role of entrepreneur in conflict zones engage in lower levels of agentic behavior compared to their male counterparts. Successful entrepreneurs (male and female) rely extensively on communal behavior in their ventures. When it comes to community development, male entrepreneurs engaging in agentic behavior, seem to mentor aspiring entrepreneurs more than females. Females relying on communal behavior engage in more mentoring of aspiring entrepreneurs than males. Originality/value An understanding of the unique gender dynamics underlying entrepreneurial behavior in conflict zones remains incomplete. The study introduces evidence that gender differences, as well as social factors, combine with the unique characteristics of conflict zones resulting in different behavioral paths to entrepreneurial success. The analytical method introduces some statistical tools to scholars attempting to understand the unique conflict zone context. As such, the study provides guidance for scholars working in this context, as well as NGO’s and other institutions seeking to train entrepreneurs and improve economic conditions in conflict zones.

Abstract Southern blight disease, caused by the fungal pathogen Athelia rolfsii, suppresses plant growth and reduces product yield in Cannabis sativa agriculture. Mechanisms of pathology of this soil‐borne disease remain poorly understood, with disease management strategies reliant upon broad‐spectrum antifungal use. Exposure to chitosan, a natural elicitor, has been proposed as an alternative method to control diverse fungal diseases in an eco‐friendly manner. In this study, C. sativa plants were grown in the Root‐TRAPR system, a transparent hydroponic growth device, where plant roots were primed with .2% colloidal chitosan prior to A. rolfsii inoculation. Both chitosan‐primed and unprimed inoculated plants displayed classical symptoms of wilting and yellowish leaves, indicating successful infection. Non‐primed infected plants showed increased shoot defense responses with doubling of peroxidase and chitinase activities. The levels of growth and defense hormones including auxin, cytokinin, and jasmonic acid were increased 2–5‐fold. In chitosan‐primed infected plants, shoot peroxidase activity and phytohormone levels were decreased 1.5–4‐fold relative to the unprimed infected plants. When compared with shoots, roots were less impacted by A. rolfsii infection, but the pathogen secreted cell wall‐degrading enzymes into the root‐growth solution. Chitosan priming inhibited root growth, with root lengths of chitosan‐primed plants approximately 65% shorter than the control, but activated root defense responses, with root peroxidase activity increased 2.7‐fold along with increased secretion of defense proteins. The results suggest that chitosan could be an alternative platform to manage southern blight disease in C. sativa cultivation; however, further optimization is required to maximize effectiveness of chitosan.

Fungal pathogens pose a major threat to Cannabis sativa production, requiring safe and effective management procedures to control disease. Chitin and chitosan are natural molecules that elicit plant defense responses. Investigation of their effects on C. sativa will advance understanding of plant responses towards elicitors and provide a potential pathway to enhance plant resistance against diseases. Plants were grown in the in vitro Root-TRAPR system and treated with colloidal chitin and chitosan. Plant morphology was monitored, then plant tissues and exudates were collected for enzymatic activity assays, phytohormone quantification, qPCR analysis and proteomics profiling. Chitosan treatments showed increased total chitinase activity and expression of pathogenesis-related (PR) genes by 3-5 times in the root tissues. In the exudates, total peroxidase and chitinase activities and levels of defense proteins such as PR protein 1 and endochitinase 2 were increased. Shoot development was unaffected, but root development was inhibited after chitosan exposure. In contrast, chitin treatments had no significant impact on any defense parameters, including enzymatic activities, hormone quantities, gene expression levels and root secreted proteins. These results indicate that colloidal chitosan, significantly enhancing defense responses in C. sativa root system, could be used as a potential elicitor, particularly in hydroponic scenarios to manage crop diseases.

High temperatures inhibit plant growth. A proposed strategy for improving plant productivity under elevated temperatures is the use of plant growth-promoting rhizobacteria (PGPR). While the effects of PGPR on plant shoots have been extensively explored, roots—particularly their spatial and temporal dynamics—have been hard to study, due to their below-ground nature. Here, we characterized the time- and tissue-specific morphological changes in bacterized plants using a novel non-invasive high-resolution plant phenotyping and imaging platform—GrowScreen-Agar II. The platform uses custom-made agar plates, which allow air exchange to occur with the agar medium and enable the shoot to grow outside the compartment. The platform provides light protection to the roots, the exposure of it to the shoots, and the non-invasive phenotyping of both organs. Arabidopsis thaliana, co-cultivated with Paraburkholderia phytofirmans PsJN at elevated and ambient temperatures, showed increased lengths, growth rates, and numbers of roots. However, the magnitude and direction of the growth promotion varied depending on root type, timing, and temperature. The root length and distribution per depth and according to time was also influenced by bacterization and the temperature. The shoot biomass increased at the later stages under ambient temperature in the bacterized plants. The study offers insights into the timing of the tissue-specific, PsJN-induced morphological changes and should facilitate future molecular and biochemical studies on plant–microbe–environment interactions.

Examine 9-year trends in mortality and readmission following atrial fibrillation (AF) hospitalisation in metropolitan and regional Australian settings.

Background Plant growth devices, for example, rhizoponics, rhizoboxes, and ecosystem fabrication (EcoFAB), have been developed to facilitate studies of plant root morphology and plant-microbe interactions in controlled laboratory settings. However, several of these designs are suitable only for studying small model plants such as Arabidopsis thaliana and Brachypodium distachyon and therefore require modification to be extended to larger plant species like crop plants. In addition, specific tools and technical skills needed for fabricating these devices may not be available to researchers. Hence, this study aimed to establish an alternative protocol to generate a larger, modular and reusable plant growth device based on different available resources. Results Root-TRAPR (Root-Transparent, Reusable, Affordable three-dimensional Printed Rhizo-hydroponic) system was successfully developed. It consists of two main parts, an internal root growth chamber and an external structural frame. The internal root growth chamber comprises a polydimethylsiloxane (PDMS) gasket, microscope slide and acrylic sheet, while the external frame is printed from a three-dimensional (3D) printer and secured with nylon screws. To test the efficiency and applicability of the system, industrial hemp ( Cannabis sativa ) was grown with or without exposure to chitosan, a well-known plant elicitor used for stimulating plant defense. Plant root morphology was detected in the system, and plant tissues were easily collected and processed to examine plant biological responses. Upon chitosan treatment, chitinase and peroxidase activities increased in root tissues (1.7- and 2.3-fold, respectively) and exudates (7.2- and 21.6-fold, respectively). In addition, root to shoot ratio of phytohormone contents were increased in response to chitosan. Within 2 weeks of observation, hemp plants exhibited dwarf growth in the Root-TRAPR system, easing plant handling and allowing increased replication under limited growing space. Conclusion The Root-TRAPR system facilitates the exploration of root morphology and root exudate of C. sativa under controlled conditions and at a smaller scale. The device is easy to fabricate and applicable for investigating plant responses toward elicitor challenge. In addition, this fabrication protocol is adaptable to study other plants and can be applied to investigate plant physiology in different biological contexts, such as plant responses against biotic and abiotic stresses.

Microorganisms have evolved several mechanisms to mobilize and mineralize occluded and insoluble phosphorus (P), thereby promoting plant growth in terrestrial ecosystems. However, the linkages between microbial P-solubilization traits and the preponderance of insoluble P in natural ecosystems are not well known. We tested the P solubilization traits of hundreds of culturable bacteria representative of the rhizosphere from a natural gradient where P concentration and bioavailability decline as soil becomes progressively more weathered. Aluminum, iron phosphate and organic P (phytate) were expected to dominate in more weathered soils. A defined cultivation medium with these chemical forms of P was used for isolation. A combination of soil chemical, spectroscopic analyses and 16S rRNA gene sequencing were used to understand the in situ ability for solubilization of these predominant forms of P. Locations with more occluded and organic P harbored the greatest abundance of P-mobilizing microorganisms, especially Burkholderiaceae ( Caballeronia and Paraburkholderia spp.). Nearly all bacteria utilized aluminum phosphate, however fewer could subsist on iron phosphate (FePO 4 ) or phytate. Microorganisms isolated from phytic acid were also most effective at solubilizing FePO 4 , suggesting that phytate solubilization may be linked to the ability to solubilize Fe. Significantly, we observed Fe to be co-located with P in organic patches in soil. Siderophore addition in lab experiments reinstated phytase mediated P-solubilization from Fe-phytate complexes. Taken together, these results indicate that metal-organic-P complex formation may limit enzymatic P solubilization from phytate in soil. Additionally, the linked traits of phytase and siderophore production were mostly restricted to specific clades within the Burkholderiaceae . We propose that Fe complexation of organic P (e.g., phytate) represents a major constraint on P turnover and availability in acidic soils, as only a limited subset of bacteria appear to possess the traits required to access this persistent pool of soil P.

Endophytic nitrogen-fixing (diazotrophic) bacteria are essential members of the microbiome of switchgrass (Panicum virgatum), considered to be an important commodity crop in bioenergy production. While endophytic diazotrophs are known to provide fixed atmospheric nitrogen to their host plant, there are many other plant growth-promoting (PGP) capabilities of these organisms to be demonstrated. The diversity of PGP traits across different taxa of switchgrass-colonizing endophytes is understudied, yet critical for understanding endophytic function and improving cultivation methods of important commodity crops. Here, we present the isolation and characterization of three diazotrophic endophytes: Azospirillum agricola R1C, Klebsiella variicola F10Cl, and Raoultella terrigena R1Gly. Strains R1C and F10Cl were isolated from switchgrass and strain R1Gly, while isolated from tobacco, is demonstrated herein to colonize switchgrass. Each strain exhibited highly diverse genomic and phenotypic PGP capabilities. Strain F10Cl and R1Gly demonstrated the highest functional similarity, suggesting that, while endophyte community structure may vary widely based on host species, differences in functional diversity are not a clearly delineated. The results of this study advance our understanding of diazotrophic endophyte diversity, which will allow us to design robust strategies to improve cultivation methods of many economically important commodity crops.

Accumulation of p-hydroxybenzoic acid (PHBA) in soil causes autotoxicity stress in cucumber. When the stress is mitigated by PHBA-degrading bacteria, plant metabolites have not been detected. To explore mechanisms underlining the mitigation, plant metabolites have not been combined with rhizospheric microbes, antioxidant and soil enzymes. In this study, a strain P620 of Klebsiella decomposed PHBA to acetyl CoA. Cucumber was sown into soil supplemented with P620 and/or PHBA. After addition with P620, P620 colonization and the enriched bacterial genera were observed in rhizosphere. Compared to PHBA stress alone, the combination of P620 application and PHBA stress improved plant growth, decreased PHBA concentration in soil, and increased the activities of five soil enzymes and eight antioxidant enzymes in leaves. Metabolomic and transcriptomic analysis highlighted that P620 application decreased the intensities of MAG(18:3) isomer 4, MAG(18:3) isomer 2, lysoPC 18:3 (2n isomer), 2'-deoxyadenosine-5'-monophosphate, pyridoxine, and glucarate O-phosphoric acid in PHBA-stressed leaves and down-regulated the expression of genes related to these metabolites. We propose a mechanism that P620 application alters microbial communities in PHBA-contaminated soil. Thus, the application reduces PHBA concentration in soil, activates antioxidant and soil enzymes, and also influences metabolites in leaves by affecting plant transcriptome, mitigating PHBA stress in cucumber.

Algae can efficiently take up excess nutrients from waterways, making them a valuable resource potentially capable of replacing synthesized and mined fertilizers for agriculture. The capacity of algae to fertilize crops has been quantified, but it is not known how the algae-derived nutrients become available to plants. We aimed to address this question: what are the temporal dynamics of plant growth responses to algal biomass? to better propose mechanisms by which plants acquire nutrients from algal biomass and thereby study and promote those processes in future agricultural applications. Data from various sources were transformed and used to reconstruct the nutrient release from the algae Chlorella vulgaris and subsequent uptake by wheat (Triticum aestivum L.) (as reported in Schreiber et al., 2018). Plants had received 0.1x or 1x dried algae or wet algae, or zero, 0.1x or 1x mineral fertilizer calculated from agricultural practices for P application and grown to 55 days in three soils. Contents of P and other nutrients acquired from algae were as high as from mineral fertilizer, but varied based on moisture content and amount of algae applied to soils (by 55 days after sowing plants with 1x mineral fertilizer and 1x dried algae had 5.6 mg P g DWshoot; 2.2-fold more than those with 0 or 0.1x mineral fertilizer, 0.1x dried algae and wet algae, and 1x wet algae). Absolute and relative leaf area growth and estimated P uptake rates showed similar dynamics, indicating that wheat acquires P from algae quickly. A model proposes that algal fertilizer promotes wheat growth after rapid transformation in soil to inorganic nutrients. We conclude theoretically that phosphorus from algal biomass is available to wheat seedlings upon its application and is released gradually over time with minor differences related to moisture content on application. The growth and P uptake kinetics hint at nutrient forms, including N, and biomass stimulation worthy of research to further exploit algae in sustainable agriculture practices. Temporal resolved phenotype analyses in combination with a mass-balance approach is helpful for understanding resource uptake from recycled and biofertilizer sources by plants.

Salinization of soil with sodium chloride ions inhibits plant functions, causing reduction of yield of crops. Salt tolerant microorganisms have been studied to enhance crop growth under salinity. This review describes the performance of endophytic fungi applied to crops as a supplement to plant genetics or soil management to alleviate salt stress in crops. This is achieved via inducing systemic resistance, increasing the levels of beneficial metabolites, activating antioxidant systems to scavenge ROS, and modulating plant growth phytohormones. Colonization by endophytic fungi improves nutrient uptake and maintains ionic homeostasis by modulating ion accumulation, thereby restricting the transport of Na + to leaves and ensuring a low cytosolic Na + :K + ratio in plants. Participating endophytic fungi enhance transcripts of genes encoding the high Affinity Potassium Transporter 1 (HKT1) and the inward-rectifying K + channels KAT1 and KAT2, which play key roles in regulating Na + and K + homeostasis. Endophytic-induced interplay of strigolactones play regulatory roles in salt tolerance by interacting with phytohormones. Future research requires further attention on the biochemical, molecular and genetic mechanisms crucial for salt stress resistance requires further attention for future research. Furthermore, to design strategies for sustained plant health with endophytic fungi, a new wave of exploration of plant-endophyte responses to combinations of stresses is mandatory.

Continuous-cropping leads to obstacles in crop productivity by the accumulation of p-hydroxybenzoic acid (PHBA) and ferulic acid (FA). In this study, a strain CFA of Pseudomonas was shown to have a higher PHBA- and FA-degrading ability in media and soil and the mechanisms underlying this were explored. Optimal conditions for PHBA and FA degradation by CFA were 0.2 g/l of PHBA and FA, 37°C, and pH 6.56. Using transcriptome analysis, complete pathways that converted PHBA and FA to acetyl coenzyme A were proposed in CFA. When CFA was provided with PHBA and FA, we observed upregulation of genes in the pathways and detected intermediate metabolites including vanillin, vanillic acid, and protocatechuic acid. Moreover, 4-hydroxybenzoate 3-monooxygenase and vanillate O-demethylase were rate-limiting enzymes by gene overexpression. Knockouts of small non-coding RNA (sRNA) genes, including sRNA 11, sRNA 14, sRNA 20, and sRNA 60, improved the degradation of PHBA and FA. When applied to cucumber-planted soil supplemented with PHBA and FA, CFA decreased PHBA and FA in soil. Furthermore, a reduction of superoxide radical, hydrogen peroxide, and malondialdehyde in cucumber was observed by activating superoxide dismutase, catalase, glutathione peroxidase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase in seedlings, increasing the reduced glutathione and ascorbate in leaves, and inducing catalase, urease, and phosphatase in the rhizosphere. CFA has potential to mitigate PHBA and FA stresses in cucumber and alleviate continuous-cropping obstacles.

A non-invasive plant phenotyping platform, GrowScreen-PaGe, was used to resolve the dynamics of shoot and root growth of the model cereal Brachypodium (Brachypodium distachyon Bd21-3) in response to the plant growth promoting (PGP) bacteria Azospirillum (Azospirillum brasilense Sp245). Inoculated Brachypodium plants had greater early vigor and higher P use efficiency than non-inoculated Brachypodium at low P and low temperature conditions. Root systems were imaged non-invasively at eight time points and data combined with leaf area, shoot biomass and nutrient content from destructive subsamples at 7, 14 and 21 days after inoculation (DAI). Azospirillum colonisation of roots improved Brachypodium shoot and, to a greater degree, root growth in three independent experiments. Inoculation promoted P use efficiency in shoots but not P concentration or uptake, despite increased total root length. Longer roots in inoculated plants arose from twofold faster branch root growth but slower axile root growth, detected at 11 DAI. Analysis of the spatio-temporal phenotypes indicated that the effects of Azospirillum inoculation increased as shoot P concentration declined, but the magnitude depended on the time after inoculation and growth rate of branch roots compared to axile roots. High throughput plant phenotyping platforms allow the details of plant-microorganism symbioses to be resolved, offering insights into the timing of changes in different tissues to allow molecular mechanisms to be determined.

As agriculture and food security face unprecedented challenges, emerging agricultural innovations and existing practices require ongoing examination in the context of sustainability. In this review, we focus on the use of probiotic microorganisms for improved plant production. As plants are enormously diverse, emphasis is placed on the fundamental sites of plant-microbe interactions regarding benefits and challenges encountered when altering the microbiome of these locations. The soil, the external plant epidermis, and internal plant tissue are considered in discussion regarding the type of plant probiotic application. Plant probiotics range from broader soil beneficial microorganisms (such as Trichoderma spp.) through to specialised epiphytes and endophytes (such as root nodule bacteria). As each site of interaction affects plant growth differently, potential outcomes from the introduction of these exogenous microorganisms are discussed with regard to plant productivity. Finally, recommendations regarding regulation and future use of plant probiotics are points of consideration throughout this review.

Plant growth-promoting rhizobacteria (PGPR) are known to improve plant performance by multiple mechanisms, such as the production of beneficial hormones, the enhancement of plant nutritional status, and the reduction of the stress-related damage.The interaction between plants and PGPR becomes of particular interest in environments that are characterized by suboptimal growing conditions, e.g., high or low temperatures, drought, soil salinity, and nutrient scarcity.The positive role of PGPR will become even more appealing in the future, as world agriculture is facing issues as climate change and soil degradation.This chapter aims to discuss the main mechanisms of the interaction between PGPR and plants and will focus of how PGPR can decrease abiotic stress damage in cereals, which are critical crops for human diet.

To measure the effect of veterans’ preference on U.S. federal workforce quality, researchers have assessed whether military veterans advance in their federal careers at a different rate than nonveterans. This research, however, has produced mixed results. In research concerning recent employee cohorts, nonveterans outpace veterans’ advancement, implying that veterans’ preference lessens employee quality. In older cohorts, veterans and nonveterans advance comparably. The latter research, however, controls for employees’ entry positions, whereas research concerning recent cohorts does not do so, thus inhibiting direct comparison of results. To facilitate such comparisons, we controlled for veterans’ and nonveterans’ entry positions in a study of career advancement among all white-collar, U.S. executive branch workers entering employment from 1992 to 2013. In these recent cohorts, we find roughly equivalent rates of career advancement among veterans and nonveterans when controlling for entry positions. This finding holds when using grade or pay increases as measures of advancement.

The management of the fuzzy front end (FFE) phase of innovation is crucial to the ultimate success of new product and process initiatives. A critical challenge that teams face at this stage is dealing with equivocality - the extent to which project participants grapple with multiple, and plausibly conflicting, meanings and interpretations of the information available to them (Daft and Lengel, 1986; Weick, 1979). While initially, a certain level of equivocality is beneficial for enhancing teams' creativity and preventing early closure, at some point it must be resolved in order for an idea to become a viable New Product Development (NPD) project. This study employs a social networks perspective to understand how different types of informal work-based relations and their structural properties affect equivocality on project teams in the FEL In particular, it examines the structural effects of two types of social relations and their associated networks-those of technical-advice and friendship ties. The findings suggest that while high density in projects' technical-advice network is likely to reduce equivocality, high density in projects' friendship network is likely to increase it. More interestingly, having multiple members on projects who are highly central in the lab's technical-advice network tends to increase equivocality unless it is balanced with members who occupy positions of high centrality in the lab's friendship network. In addition to contributing to the scholarship on NPD, FFE, and social networks, the results offer managerial insights for deploying social networks in order to assemble NPD teams and structure the flows of communication on projects so as to resolve equivocality in the FFE.

Hexavalent Chromium [Cr(VI)] is a widespread contaminant found in soil, sediment, and ground water in several DOE sites, including Hanford 100 H area. In order to stimulate microbially mediated reduction of Cr(VI) at this site, a poly-lactate hydrogen release compound was injected into the chromium contaminated aquifer. Targeted enrichment of dominant nitrate-reducing bacteria post injection resulted in the isolation of Pseudomonas stutzeri strain RCH2. P. stutzeri strain RCH2 was isolated using acetate as the electron donor and is a complete denitrifier. Experiments with anaerobic washed cell suspension of strain RCH2 revealed it could reduce Cr(VI) and Fe(III). The genome of strain RCH2 was sequenced using a combination of Illumina and 454 sequencing technologies and contained a circular chromosome of 4.6 Mb and three plasmids. Global genome comparisons of strain RCH2 with six other fully sequenced P. stutzeri strains revealed most genomic regions are conserved, however strain RCH2 has an additional 244 genes, some of which are involved in chemotaxis, Flp pilus biogenesis and pyruvate/2-oxogluturate complex formation.