The ability to recognize and respond to environmental signals is essential for plants. In response to environmental changes, the status of a plant is transmitted to other plants in the form of ...signals such as volatiles. Root-associated bacteria trigger the release of plant volatile organic compounds (VOCs). However, the impact of VOCs on the rhizosphere microbial community of neighbouring plants is not well understood. Here, we investigated the effect of VOCs on the rhizosphere microbial community of tomato plants inoculated with a plant growth-promoting rhizobacterium Bacillus amyloliquefaciens strain GB03 and that of their neighbouring plants. Interestingly, high similarity (up to 69%) was detected in the rhizosphere microbial communities of the inoculated and neighbouring plants. Leaves of the tomato plant treated with strain GB03-released β-caryophyllene as a signature VOC, which elicited the release of a large amount of salicylic acid (SA) in the root exudates of a neighbouring tomato seedling. The exposure of tomato leaves to β-caryophyllene resulted in the secretion of SA from the root. Our results demonstrate for the first time that the composition of the rhizosphere microbiota in surrounding plants is synchronized through aerial signals from plants.
Upon sensing attack by pathogens and insect herbivores, plants release complex mixtures of volatile compounds. Here, we show that the infection of lima bean (Phaseolus lunatus L.) plants with the ...non‐host bacterial pathogen Pseudomonas syringae pv. tomato led to the production of microbe‐induced plant volatiles (MIPVs). Surprisingly, the bacterial type III secretion system, which injects effector proteins directly into the plant cytosol to subvert host functions, was found to prime both intra‐ and inter‐specific defense responses in neighbouring wild tobacco (Nicotiana benthamiana) plants. Screening of each of 16 effectors using the Pseudomonas fluorescens effector‐to‐host analyser revealed that an effector, HopP1, was responsible for immune activation in receiver tobacco plants. Further study demonstrated that 1‐octen‐3‐ol, 3‐octanone and 3‐octanol are novel MIPVs emitted by the lima bean plant in a HopP1‐dependent manner. Exposure to synthetic 1‐octen‐3‐ol activated immunity in tobacco plants against a virulent pathogen Pseudomonas syringae pv. tabaci. Our results show for the first time that a bacterial type III effector can trigger the emission of C8 plant volatiles that mediate defense priming via plant–plant interactions. These results provide novel insights into the role of airborne chemicals in bacterial pathogen‐induced inter‐specific plant–plant interactions.
Our results demonstrated two significant progresses on microbe‐induced plant volatile (MIPV). First, out of intensive screening to identify bacterial determinant(s) that induce plant volatiles to increase bacterial immunity on neighbouring plant, we newly identified a bacterial type III effector HopP1 from Pseudomonas syringae pv. tomato corresponding to MIPV. Secondly, the bacterial type III effector HopP1 induces the production of C8 volatile organic compounds, 1‐octen‐3‐ol, 3‐octanone and 3‐octanol on lima bean that in turn interspecifically prime plant defense against virulent bacterial pathogen P. syrinage pv. tabaci on neighbouring plant Nicotiana benthamiana. To our best knowledge, this is the first studies that type III secretion system–dependent bacterial effectors induce plant volatiles.
Summary
Underground roots normally reside in darkness. However, they are often exposed to ambient light that penetrates through cracks in the soil layers which can occur due to wind, heavy rain or ...temperature extremes. In response to light exposure, roots produce reactive oxygen species (ROS) which promote root growth. It is known that ROS‐induced growth promotion facilitates rapid escape of the roots from non‐natural light. Meanwhile, long‐term exposure of the roots to light elicits a ROS burst, which causes oxidative damage to cellular components, necessitating that cellular levels of ROS should be tightly regulated in the roots. Here we demonstrate that the red/far‐red light photoreceptor phytochrome B (phyB) stimulates the biosynthesis of abscisic acid (ABA) in the shoots, and notably the shoot‐derived ABA signals induce a peroxidase‐mediated ROS detoxification reaction in the roots. Accordingly, while ROS accumulate in the roots of the phyb mutant that exhibits reduced primary root growth in the light, such an accumulation of ROS did not occur in the dark‐grown phyb roots that exhibited normal growth. These observations indicate that mobile shoot‐to‐root ABA signaling links shoot phyB‐mediated light perception with root ROS homeostasis to help roots adapt to unfavorable light exposure. We propose that ABA‐mediated shoot‐to‐root phyB signaling contributes to the synchronization of shoot and root growth for optimal propagation and performance in plants.
Significance Statement
The phyB‐mediated light signals promote ABA biosynthesis in the shoots, and the shoot‐to‐root ABA signaling triggers peroxidase‐mediated ROS detoxification to ensure primary root growth under conditions when the roots are unfavorably exposed to light, possibly providing an adaptation strategy by which plants achieve a synchronized growth of the shoot and roots.
In plants, necrotic lesions occur at the site of pathogen infection through the hypersensitive response, which is followed by induction of systemic acquired resistance (SAR) in distal tissues. ...Salicylic acid (SA) induces SAR by activating NONEXPRESSER OF PATHOGENESIS-RELATED GENES1 (NPR1) through an oligomer-to-monomer reaction. However, SA biosynthesis is elevated only slightly in distal tissues during SAR, implying that SA-mediated induction of SAR requires additional factors. Here, we demonstrated that SA-independent systemic signals induce a gene encoding SNF1-RELATED PROTEIN KINASE 2.8 (SnRK2.8), which phosphorylates NPR1 during SAR. The SnRK2.8-mediated phosphorylation of NPR1 is necessary for its nuclear import. Notably, although SnRK2.8 transcription and SnRK2.8 activation are independent of SA signaling, the SnRK2.8-mediated induction of SAR requires SA. Together with the SA-mediated monomerization of NPR1, these observations indicate that SA signals and SnRK2.8-mediated phosphorylation coordinately function to activate NPR1 via a dual-step process in developing systemic immunity in Arabidopsis thaliana.
Thermal ablation using radiofrequency is a new, minimally invasive modality employed as an alternative to surgery in patients with benign thyroid nodules and recurrent thyroid cancers. The Task Force ...Committee of the Korean Society of Thyroid Radiology (KSThR) developed recommendations for the optimal use of radiofrequency ablation for thyroid tumors in 2012. As new meaningful evidences have accumulated, KSThR decided to revise the guidelines. The revised guideline is based on a comprehensive analysis of the current literature and expert consensus.
Incidental thyroid nodules are commonly detected on ultrasonography (US). This has contributed to the rapidly rising incidence of low-risk papillary thyroid carcinoma over the last 20 years. The ...appropriate diagnosis and management of these patients is based on the risk factors related to the patients as well as the thyroid nodules. The Korean Society of Thyroid Radiology (KSThR) published consensus recommendations for US-based management of thyroid nodules in 2011 and revised them in 2016. These guidelines have been used as the standard guidelines in Korea. However, recent advances in the diagnosis and management of thyroid nodules have necessitated the revision of the original recommendations. The task force of the KSThR has revised the Korean Thyroid Imaging Reporting and Data System and recommendations for US lexicon, biopsy criteria, US criteria of extrathyroidal extension, optimal thyroid computed tomography protocol, and US follow-up of thyroid nodules before and after biopsy. The biopsy criteria were revised to reduce unnecessary biopsies for benign nodules while maintaining an appropriate sensitivity for the detection of malignant tumors in small (1-2 cm) thyroid nodules. The goal of these recommendations is to provide the optimal scientific evidence and expert opinion consensus regarding US-based diagnosis and management of thyroid nodules.
Abstract
Bacteria emit volatile compounds that modulate plant growth. Previous studies reported the impacts of bacterial volatile compounds on plant growth; however, the results varied depending on ...bacterial nutrient availability. We investigated whether the effects of plant growth–inhibiting volatiles (PGIVs) and plant growth–promoting volatiles (PGPVs) depended on the perceived dose by evaluating the growth of Arabidopsis thaliana seedlings placed at 7, 14, and 21 cm away from Bacillus amyloliquefaciens GB03 colonies growing in rich medium. A large bacterial colony (500 μl inoculum) inhibited plant growth at 7 cm and promoted growth at 21 cm, whereas a small bacterial colony (100 μl inoculum) induced the opposite pattern of response. We identified pyrazine and 2,5-dimethylpyrazine as candidate PGIVs that significantly reduced plant growth at a distance of 7 cm. PGIV effects were validated by exposing plants to synthetic 2,5-dimethylpyrazine and bacteria emitting PGPVs, which showed that PGIVs overwhelm PGPVs to rapidly increase salicylic acid content and related gene expression. This is referred to as the defence-growth trade-off. Our results indicate that high PGIV concentrations suppress plant growth and promote immunity, whereas low PGPV concentrations promote growth. This study provides novel insights into the complex effects of bacterial volatile mixtures and fine-tuning of bacteria-plant interactions.
Bacillus amyloliquefaciens GB03 emits volatile pyrazines, which exhibit plant growth inhibitory activity at shorter distances between plants and the volatile source.
Abstract
Background
The present study aimed to investigate the association between oral health literacy and oral health behaviors among North Korean defectors.
Methods
This study involved the ...collection of self-reported questionnaires from 123 North Korean defectors visited a dental clinic that offered complimentary services, to receive dental treatment in a metropolitan area of South Korea from December 2017 to April 2018. Oral health literacy was measured with the Test of Korean Functional Health Literacy in Dentistry (TOKFHLiD), which consists of 30 items concerning verbal oral health literacy and 42 items concerning functional oral health literacy (28 items for reading comprehension and 14 items for numeracy). In addition, the questionnaire contains 15 and 14 items related to demographic characteristics and oral health behaviors (interest, lifestyle, diet, prevention), respectively, for a total of 101 items.
Results
The mean oral health literacy score was 44 (out of a maximum possible score of 72). Oral health literacy and oral health behaviors were positively correlated (
r
= 0.526,
P
< 0.001), and oral health literacy also had a significant effect on oral health behaviors (Beta = 0.26, 95% CI: 0.04–0.33). However, although functional oral health literacy had a significant effect on oral health behaviors (Beta = 0.20, 95% CI: 0.01–0.43), verbal oral health literacy did not (Beta = 0.13, 95% CI: − 0.06-037).
Conclusions
Educational interventions are needed to improve oral health literacy, and thus oral health behaviors, as a part of the health promotion measures undertaken to facilitate the stable adjustment of North Korean defectors in South Korean society.
A multichannel/multicolor visible light communication (VLC) system using entirely organic components, including organic light emitting diodes (OLEDs) and organic photodiodes (OPDs), is developed to ...demonstrate indoor lighting applications where the integration of OLEDs and OPDs has significant potential. To achieve this, tricolor (Red/Green/Blue(R/G/B))‐selective OPD arrays for the receiver and tricolor OLED arrays for the emitter are developed. For (R/G/B)‐selective OPDs, a Fabry–Pérot electrode to enhance color selectivity and a thick junction structure to effectively accommodate a wide range of driving voltages are introduced. For tricolor OLEDs, fluorescent‐emitting materials are used to enhance the operating frequency in addition to introducing a cavity structure to achieve narrow emission. Utilizing these spectrally refined tricolor OPDs/OLEDs, a VLC system is designed for indoor lighting applications, and a systematic analysis of their signal‐to‐interference ratio dependence on the distance or angle between the transmitter and receiver is performed. The study's findings indicate the importance of emission angle‐dependent wavelength shift of the OLED and the luminosity function, which varies with wavelength, in the R/G/B mixed‐white‐light‐based VLC systems. Finally, the feasibility of VLC using tricolor OPDs/OLEDs in the real‐life context of indoor white‐color lighting is demonstrated, showing that the transmitted data patterns well‐matched the received data patterns.
A visible light communication platform using (R/G/B)‐selective organic photodiode arrays as receivers and (R/G/B) organic light‐emitting diodes as emitters is developed and analyzed to study how the geometry effect of each organic receiver and emitter affects data transmission. Based on this, the first organic material‐based white‐light optical communication system is demonstrated.
The phytohormone abscisic acid (ABA) plays crucial roles in various physiological processes, including responses to abiotic stresses, in plants. Recently, multiple ABA transporters were identified. ...The loss-of-function and gain-of-function mutants of these transporters show altered ABA sensitivity and stomata regulation, highlighting the importance of ABA transporters in ABA-mediated processes. However, how the activity of these transporters is regulated remains elusive. Here, we show that spatial regulation of ATP BINDING CASETTE G25 (ABCG25), an ABA exporter, is an important mechanism controlling its activity. ABCG25, as a soluble green fluorescent protein (sGFP) fusion, was subject to posttranslational regulation via clathrin-dependent and adaptor protein complex-2-dependent endocytosis followed by trafficking to the vacuole. The levels of sGFP:ABCG25 at the plasma membrane (PM) were regulated by abiotic stresses and exogenously applied ABA; PM-localized sGFP:ABCG25 decreased under abiotic stress conditions via activation of endocytosis in an ABA-independent manner, but increased upon application of exogenous ABA via activation of recycling from early endosomes in an ABA-dependent manner. Based on these findings, we propose that the spatial regulation of ABCG25 is an important component of the mechanism by which plants fine-tune cellular ABA levels according to cellular and environmental conditions.
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