MAP Kinase-Mediated Negative Regulation of Symbiotic Nodule Formation in Medicago truncatula

Mitogen-activated protein kinase (MAPK) signaling cascades play critical roles in various cellular events in plants, including stress responses, innate immunity, hormone signaling, and cell specificity. MAPK-mediated stress signaling is also known to negatively regulate nitrogen-fixing symbiotic interactions, but the molecular mechanism of the MAPK signaling cascades underlying the symbiotic nodule development remains largely unknown. We show that the MtMKK5-MtMPK3/6 signaling module negatively regulates the early symbiotic nodule formation, probably upstream of ERN1 (ERF Required for Nodulation 1) and NSP1 (Nod factor Signaling Pathway 1) in Medicago truncatula. The overexpression of MtMKK5 stimulated stress and defense signaling pathways but also reduced nodule formation in M. truncatula roots. Conversely, a MAPK specific inhibitor, U0126, enhanced nodule formation and the expression of an early nodulation marker gene, MtNIN. We found that MtMKK5 directly activates MtMPK3/6 by phosphorylating the TEY motif within the activation loop and that the MtMPK3/6 proteins physically interact with the early nodulation-related transcription factors ERN1 and NSP1. These data suggest that the stress signaling-mediated MtMKK5/MtMPK3/6 module suppresses symbiotic nodule development via the action of early nodulation transcription factors.

Stimuli-responsive magneto-/electro-chromatic color-tunable hydrophobic surface modified Fe3O4@SiO2 core–shell nanoparticles for reflective display approaches

Magneto-/electro-chromatic reflective color tunability is confirmed using hydrophobic surface modified magnetite nanoparticles. The optical reflective color spectra and color gamut demonstrate the promising applications in reflective displays.

Applications of molecular markers in the discrimination of Panax species and Korean ginseng cultivars (Panax ginseng)

The development of molecular markers is one of the most useful methods for molecular breeding and marker-based molecular associated selections. Even though there is less information on the reference genome, molecular markers are indispensable tools for determination of genetic variation and identification of species with high levels of accuracy and reproducibility. The demand for molecular approaches for marker-based breeding and genetic discriminations in Panax species has greatly increased in recent times and has been successfully applied for various purposes. However, owing to the existence of diverse molecular techniques and differences in their principles and applications, there should be careful consideration while selecting appropriate marker types. In this review, we outline the recent status of different molecular marker applications in ginseng research and industrial fields. In addition, we discuss the basic principles, requirements, and advantages and disadvantages of the most widely used molecular markers, including restriction fragment length polymorphism, random amplified polymorphic DNA, sequence tag sites, simple sequence repeats, and single nucleotide polymorphisms.

Whole genome de novo sequencing and genome annotation of the world popular cultivated edible mushroom, Lentinula edodes

Lentinula edodes, the popular shiitake mushroom, is one of the most important cultivated edible mushrooms. It is used as a food and for medicinal purposes. Here, we present the 46.1 Mb draft genome of L. edodes, comprising 13,028 predicted gene models. The genome assembly consists of 31 scaffolds. Gene annotation provides key information about various signaling pathways and secondary metabolites. This genomic information should help establish the molecular genetic markers for MAS/MAB and increase our understanding of the genome structure and function.

Induction of systemic resistance in Panax ginseng against Phytophthora cactorum by native Bacillus amyloliquefaciens HK34

BACKGROUND

Korean ginseng (Panax ginseng Meyer) is a perennial herb prone to various root diseases, with Phytophthora cactorum being considered one of the most dreaded pathogens. P. cactorum causes foliar blight and root rot. Although chemical pesticides are available for disease control, attention has been shifted to viable, eco-friendly, and cost-effective biological means such as plant growth-promoting rhizobacteria (PGPR) for control of diseases.

METHODS

Native Bacillus amyloliquefaciens strain HK34 was isolated from wild ginseng and assessed as a biological control agent for ginseng. Leaves from plants treated with HK34 were analyzed for induced systemic resistance (ISR) against P. cactorum in square plate assay. Treated plants were verified for differential expression of defense-related marker genes using quantitative reverse transcription polymerase chain reaction.

RESULTS

A total of 78 native rhizosphere bacilli from wild P. ginseng were isolated. One of the root-associated bacteria identified as B. amyloliquefaciens strain HK34 effectively induced resistance against P. cactorum when applied as soil drench once (99.1% disease control) and as a priming treatment two times in the early stages (83.9% disease control). A similar result was observed in the leaf samples of plants under field conditions, where the percentage of disease control was 85.6%. Significant upregulation of the genes PgPR10, PgPR5, and PgCAT in the leaves of plants treated with HK34 was observed against P. cactorum compared with untreated controls and only pathogen-treated plants.

CONCLUSION

The results of this study indicate HK34 as a potential biocontrol agent eliciting ISR in ginseng against P. cactorum.

Therapeutic targeting of epigenetic components in amyotrophic lateral sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease characterized by degeneration of motor neuron and glial activation followed by the progressive muscle loss and paralysis. Numerous distinct therapeutic interventions have been examined but currently ALS does not have a cure or an efficacious treatment for the disorder. Glutamate- induced excitotoxicity, inflammation, mitochondrial dysfunction, oxidative stress, protein aggregation, transcription deregulation, and epigenetic modifications are associated with the pathogenesis of ALS and known to be therapeutic targets in ALS. In this review, we discuss translational pharmacological studies targeting epigenetic components to ameliorate ALS. Understanding of the epigenetic mechanisms will provide novel insights that will further identify potential biological markers and therapeutic approaches for treating ALS. A combination of treatments that modulate epigenetic components and multiple targets may prove to be the most effective therapy for ALS.

A Large National Cohort Study of the Association between Bisphosphonates and Osteonecrosis of the Jaw in Patients with Osteoporosis

The purpose of this study was to examine the association between bisphosphonate exposure and osteonecrosis of the jaw (ONJ) in Korean patients with osteoporosis. A nested case-control study was performed using the claims database during 2002 to 2010 provided by the National Health Insurance Service. We identified a cohort of individuals with diagnosis of osteoporosis during 2002 to 2010. Cases and controls were identified during 2004 to 2010, and the date of potential cases of ONJ was defined as the index date. Bisphosphonate exposure was evaluated during 2 y prior to the index date. The association between bisphosphonate exposure and ONJ was tested by performing a conditional logistic regression analysis for matched data, and odds ratios (ORs) with 95% confidence intervals (CIs) were presented. Subjects were classified as nonuser, recent user, past user, or continuous user, depending on the prescription of bisphosphonates in 2 periods (1 to 2 y and 0 to 1 y prior to the index date). Continuous users were defined as patients who were exposed to bisphosphonate in both periods. We also examined the impact of bisphosphonate medication compliance by measuring the cumulative duration of exposure (CDE) on the risk of ONJ. A total of 212 cases with ONJ and 2,120 controls matched by sex, age, income level, and insurance type were identified among 109,787 patients with osteoporosis out of 1,025,340 enrollees in the sample cohort. The odds of having ONJ after adjusting for patient comorbidities significantly increased in continuous users of bisphosphonates (OR, 3.9; 95% CI, 2.4 to 6.2) compared to nonusers. Increased odds of ONJ were observed as CDE increased. The adjusted OR in patients with 1.5 y < CDE ≤ 2 y prior to the index date was 7.8 (95% CI, 4.0 to 15.5) versus nonusers. Our study results support significantly increased occurrences of potential ONJ in patients with osteoporosis who were exposed to bisphosphonates compared to those without exposure.

Why do wild bonobos not use tools like chimpanzees do?

One of the most conspicuous behavioural differences among great apes is the paucity of tool use among wild bonobos (Pan paniscus) in comparison to chimpanzees (Pan troglodytes) who are one of the most prolific and skilled tool users in the animal kingdom. This is in spite of the fact that bonobo tool use repertories are as large and diverse as chimpanzees’ in captive settings. In this study, we compared tool using behaviours and potential drivers of these behaviours in the Wamba bonobo population located in central Democratic Republic of Congo with the Goualougo chimpanzee population of northern Republic of Congo. The tool use repertoire of wild bonobos was comprised of only 13 behaviours, compared to 42 for chimpanzees. However, the number of tool behaviours observed in each study site was similar between bonobos and chimpanzees, and many types of tool use for social, self-grooming/stimulation, and comfort/protection functions were commonly used by both species. A marked difference is that 25 of 42 tool behaviours exhibited by chimpanzees are performed for feeding, in contrast to a single report of bonobos using a leaf sponge to drink water. We examined whether the differences in tool use repertoires can be explained by the necessity, opportunity, relative profitability, or invention hypotheses. We found that habitat composition and fluctuation of fruit production at these two sites were similar, particularly when compared with variation observed between sites within each species. Thus it was unlikely that the necessity hypothesis explains the lack of tool use for feeding in bonobos. Though further study at Wamba is needed, we did not identify any obvious differences in prey availability that would indicate differences in tool using opportunities between the sites. This study could not test the relative profitability hypothesis, and further research is needed on whether tool use is the most efficient means of calorie or protein intake for wild apes. Bonobos at Wamba formed much larger and stable parties than chimpanzees at Goualougo, which was contrary to the prediction by the invention hypothesis. Another explanation is that differences in tool use behaviour between bonobos and chimpanzees might not be explained by the current ecological or social conditions, but rather by circumstances during the Pleistocene Epoch. The observed species differences might also reflect divergent behavioural predispositions, rather than actual differences in cognitive abilities.

CR6-interacting factor 1 is a key regulator in Aβ-induced mitochondrial disruption and pathogenesis of Alzheimer's disease

Mitochondrial dysfunction, often characterized by massive fission and other morphological abnormalities, is a well-known risk factor for Alzheimer's disease (AD). One causative mechanism underlying AD-associated mitochondrial dysfunction is thought to be amyloid-β (Aβ), yet the pathways between Aβ and mitochondrial dysfunction remain elusive. In this study, we report that CR6-interacting factor 1 (Crif1), a mitochondrial inner membrane protein, is a key player in Aβ-induced mitochondrial dysfunction. Specifically, we found that Crif1 levels were downregulated in the pathological regions of Tg6799 mice brains, wherein overexpressed Aβ undergoes self-aggregation. Downregulation of Crif1 was similarly observed in human AD brains as well as in SH-SY5Y cells treated with Aβ. In addition, knockdown of Crif1, using RNA interference, induced mitochondrial dysfunction with phenotypes similar to those observed in Aβ-treated cells. Conversely, Crif1 overexpression prevented Aβ-induced mitochondrial dysfunction and cell death. Finally, we show that Aβ-induced downregulation of Crif1 is mediated by enhanced reactive oxygen species (ROS) and ROS-dependent sumoylation of the transcription factor specificity protein 1 (Sp1). These results identify the ROS-Sp1-Crif1 pathway to be a new mechanism underlying Aβ-induced mitochondrial dysfunction and suggest that ROS-mediated downregulation of Crif1 is a crucial event in AD pathology. We propose that Crif1 may serve as a novel therapeutic target in the treatment of AD.

Control of early seedling development by BES1/TPL/HDA19-mediated epigenetic regulation of ABI3

Seed germination and young seedling establishment should be tightly regulated to maximize plant survival and thereby enable successful propagation. Plants have evolved developmental signalling networks to integrate environmental cues for proper control of these critical processes, in which brassinosteroids are known to attenuate ABA-mediated arrest of early seedling development; however, the underlying regulatory mechanism remains elusive. Here we reveal that a BES1/TPL/HDA19 repressor complex mediates the inhibitory action of brassinosteroids on ABA responses during early seedling development. BR-activated BES1 forms a transcriptional repressor complex with TPL-HDA19, which directly facilitates the histone deacetylation of ABI3 chromatin. This event leads to the transcriptional repression of ABI3 and consequently ABI5, major ABA signalling regulators in early seedling development. Our data reveal that the BR-activated BES1-TPL-HDA19 repressor complex controls epigenetic silencing of ABI3 and thereby suppresses the ABA signalling output during early seedling development.

Biological control of Colletotrichum panacicola on Panax ginseng by Bacillus subtilis HK-CSM-1

Background

Biological control of plant pathogens using benign or beneficial microorganisms as antagonistic agents is currently considered to be an important component of integrated pest management in agricultural crops. In this study, we evaluated the potential of Bacillus subtilis strain HK-CSM-1 as a biological control agent against Colletotrichum panacicola.

Methods

The potential of B. subtilis HK-CSM-1 as a biological control agent for ginseng anthracnose was assessed. C. panacicola was inoculated to ginseng plants and the incidence and severity of disease was assessed to examine the efficacy of the bacterium as a biological control against C. panacicola.

Results

Inoculation of Panax ginseng plants with B. subtilis significantly suppressed the number of disease lesions of C. panacicola and was as effective as the chemical fungicide iminoctadine tris(albesilate). The antifungal activity of B. subtilis against C. panacicola was observed on a co-culture medium. Interestingly, treatment with B. subtilis did not significantly affect the diameter of the lesions, suggesting that the mechanism of protection was through the reduction in the incidence of infection related to the initial events of the infection cycle, including penetration and infection via spore germination and appressorium formation rather than by the inhibition of invasive growth after infection.

Conclusion

Our results suggest that B. subtilis HK-CSM-1 can be used as an effective and ecologically friendly biological control agent for anthracnose in P. ginseng.

Direct determination of exchange parameters in Cs2CuBr4 and Cs2CuCl4: high-field electron-spin-resonance studies

Spin-1/2 Heisenberg antiferromagnets Cs2CuCl4 and Cs2CuBr4 with distorted triangular-lattice structures are studied by means of electron spin resonance spectroscopy in magnetic fields up to the saturation field and above. In the magnetically saturated phase, quantum fluctuations are fully suppressed, and the spin dynamics is defined by ordinary magnons. This allows us to accurately describe the magnetic excitation spectra in both materials and, using the harmonic spin-wave theory, to determine their exchange parameters. The viability of the proposed method was proven by applying it to Cs2CuCl4, yielding J/kB=4.7(2)  K, J'/kB=1.42(7)  K, [J'/J≃0.30] and revealing good agreement with inelastic neutron-scattering results. For the isostructural Cs2CuBr4, we obtain J/kB=14.9(7)  K, J'/kB=6.1(3)  K, [J'/J≃0.41], providing exact and conclusive information on the exchange couplings in this frustrated spin system.

Insights into genomics of salt stress response in rice

Plants, as sessile organisms experience various abiotic stresses, which pose serious threat to crop production. Plants adapt to environmental stress by modulating their growth and development along with the various physiological and biochemical changes. This phenotypic plasticity is driven by the activation of specific genes encoding signal transduction, transcriptional regulation, ion transporters and metabolic pathways. Rice is an important staple food crop of nearly half of the world population and is well known to be a salt sensitive crop. The completion and enhanced annotations of rice genome sequence has provided the opportunity to study functional genomics of rice. Functional genomics aids in understanding the molecular and physiological basis to improve the salinity tolerance for sustainable rice production. Salt tolerant transgenic rice plants have been produced by incorporating various genes into rice. In this review we present the findings and investigations in the field of rice functional genomics that includes supporting genes and networks (ABA dependent and independent), osmoprotectants (proline, glycine betaine, trehalose, myo-inositol, and fructans), signaling molecules (Ca2+, abscisic acid, jasmonic acid, brassinosteroids) and transporters, regulating salt stress response in rice.