Enhanced Disease Susceptibility 1 and Salicylic Acid Act Redundantly to Regulate Resistance Gene-Mediated Signaling

Resistance (R) protein–associated pathways are well known to participate in defense against a variety of microbial pathogens. Salicylic acid (SA) and its associated proteinaceous signaling components, including enhanced disease susceptibility 1 (EDS1), non–race-specific disease resistance 1 (NDR1), phytoalexin deficient 4 (PAD4), senescence associated gene 101 (SAG101), and EDS5, have been identified as components of resistance derived from many R proteins. Here, we show that EDS1 and SA fulfill redundant functions in defense signaling mediated by R proteins, which were thought to function independent of EDS1 and/or SA. Simultaneous mutations in EDS1 and the SA–synthesizing enzyme SID2 compromised hypersensitive response and/or resistance mediated by R proteins that contain coiled coil domains at their N-terminal ends. Furthermore, the expression of R genes and the associated defense signaling induced in response to a reduction in the level of oleic acid were also suppressed by compromising SA biosynthesis in the eds1 mutant background. The functional redundancy with SA was specific to EDS1. Results presented here redefine our understanding of the roles of EDS1 and SA in plant defense

SAG101 Forms a Ternary Complex with EDS1 and PAD4 and Is Required for Resistance Signaling against Turnip Crinkle Virus

EDS1, PAD4, and SAG101 are common regulators of plant immunity against many pathogens. EDS1 interacts with both PAD4 and SAG101 but direct interaction between PAD4 and SAG101 has not been detected, leading to the suggestion that the EDS1-PAD4 and EDS1-SAG101 complexes are distinct. We show that EDS1, PAD4, and SAG101 are present in a single complex in planta. While this complex is preferentially nuclear localized, it can be redirected to the cytoplasm in the presence of an extranuclear form of EDS1. PAD4 and SAG101 can in turn, regulate the subcellular localization of EDS1. We also show that the Arabidopsis genome encodes two functionally redundant isoforms of EDS1, either of which can form ternary complexes with PAD4 and SAG101. Simultaneous mutations in both EDS1 isoforms are essential to abrogate resistance (R) protein-mediated defense against turnip crinkle virus (TCV) as well as avrRps4 expressing Pseudomonas syringae. Interestingly, unlike its function as a PAD4 substitute in bacterial resistance, SAG101 is required for R-mediated resistance to TCV, thus implicating a role for the ternary complex in this defense response. However, only EDS1 is required for HRT-mediated HR to TCV, while only PAD4 is required for SA-dependent induction of HRT. Together, these results suggest that EDS1, PAD4 and SAG101 also perform independent functions in HRT-mediated resistance

Conservation status of the dhole Cuon alpinus in north-east India, with a focus on Dampa Tiger Reserve, Mizoram

Despite the efforts invested in their conservation, the status of many threatened carnivores in key conservation landscapes remains unknown. The dhole Cuon alpinus is an Endangered social carnivore whose geographical range has contracted by c. 80% since the early 20th century. North-east India is a critical link between South Asian and South-east Asian dhole populations. In this study we compiled presence records of dholes across north-east India, from multiple sources. We also conducted camera-trap surveys in one part of this region, Dampa Tiger Reserve in the state of Mizoram. We examined the influence of ecological and management factors on fine-scale site-use by dholes in Dampa Tiger Reserve, showing a positive association of dhole site-use with sambar Rusa unicolor encounters, distance to the forest boundary and presence of forest department personnel, underscoring the importance of prey and protection. Our findings also highlight the need for targeted, multi-scale assessments of dhole ecology across other sites in north-east India

Conservation status of the dhole Cuon alpinus in north-east India, with a focus on Dampa Tiger Reserve, Mizoram

Despite the efforts invested in their conservation, the status of many threatened carnivores in key conservation landscapes remains unknown. The dhole Cuon alpinus is an Endangered social carnivore whose geographical range has contracted by c. 80% since the early 20th century. North-east India is a critical link between South Asian and South-east Asian dhole populations. In this study we compiled presence records of dholes across north-east India, from multiple sources. We also conducted camera-trap surveys in one part of this region, Dampa Tiger Reserve in the state of Mizoram. We examined the influence of ecological and management factors on fine-scale site-use by dholes in Dampa Tiger Reserve, showing a positive association of dhole site-use with sambar Rusa unicolor encounters, distance to the forest boundary and presence of forest department personnel, underscoring the importance of prey and protection. Our findings also highlight the need for targeted, multi-scale assessments of dhole ecology across other sites in north-east India

Prediction of Creep Curves of High Temperature Alloys using θ -Projection Concept

AbstractA computer program based on “MATLAB” was developed to predict creep curves of two high temperature alloys viz. a near α titanium alloy and Fe-Ni-Cr-Al alloy using θ-projection concept. Experimental creep curves generated at 600°C at different stress levels were used. This technique involves fitting of experimental creep curves according to eq εc=εt−ε0=θ1(1−e−θ2t)+θ3(eθ4t−1) to obtain θi parameters for different stress levels. Different θ-values obtained from fitting are then fitted according to eq logθi=ai+biσ+ciT+diσT and experimental strain to fracture values are fitted according to eq logεf=a+bσ+cT+dσT to obtain a set of twenty material constants (ai, bi, ci, dit), and εi), which are further used along with eq εc=εt=ε0=θ1(1−e−θ2t)+θ3(eθ4t−1) to determine four θ-values and fracture strain for each desired combination of stress and temperature in order to generate new creep strain curve. The predicted creep curves for both the alloys have been validated by generating experimental curves. Further, in order to simulate creep behaviour of components of complex geometry such as gas turbine blades and vanes this user defined material model i.e, θ-projection concept has been interfaced with ANSYS. Simulations have been carried-out and validation of the simulation results will be presented in this paper

Role of Salicylic Acid and Fatty Acid Desaturation Pathways in ssi2-Mediated Signaling

Stearoyl-acyl carrier protein desaturase-mediated conversion of stearic acid to oleic acid (18:1) is the key step that regulates the levels of unsaturated fatty acids (FAs) in cells. Our previous work with the Arabidopsis (Arabidopsis thaliana) ssi2/fab2 mutant and its suppressors demonstrated that a balance between glycerol-3-phosphate (G3P) and 18:1 levels is critical for the regulation of salicylic acid (SA)- and jasmonic acid-mediated defense signaling in the plant. In this study, we have evaluated the role of various genes that have an impact on SA, resistance gene-mediated, or FA desaturation (FAD) pathways on ssi2-mediated signaling. We show that ssi2-triggered resistance is dependent on EDS1, PAD4, EDS5, SID2, and FAD7 FAD8 genes. However, ssi2-triggered defects in the jasmonic acid pathway, morphology, and cell death phenotypes are independent of the EDS1, EDS5, PAD4, NDR1, SID2, FAD3, FAD4, FAD5, DGD1, FAD7, and FAD7 FAD8 genes. Furthermore, the act1-mediated rescue of ssi2 phenotypes is also independent of the FAD2, FAD3, FAD4, FAD5, FAD7, and DGD1 genes. Since exogenous application of glycerol converts wild-type plants into ssi2 mimics, we also studied the effect of exogenous application of glycerol on mutants impaired in resistance-gene signaling, SA, or fad pathways. Glycerol increased SA levels and induced pathogenesis-related gene expression in all but sid2, nahG, fad7, and fad7 fad8 plants. Furthermore, glycerol-induced phenotypes in various mutant lines correlate with a concomitant reduction in 18:1 levels. Inability to convert glycerol into G3P due to a mutation in the nho1-encoded glycerol kinase renders plants tolerant to glycerol and unable to induce the SA-dependent pathway. A reduction in the NHO1-derived G3P pool also results in a partial age-dependent rescue of the ssi2 morphological and cell death phenotypes in the ssi2 nho1 plants. The glycerol-mediated induction of defense was not associated with any major changes in the lipid profile and/or levels of phosphatidic acid. Taken together, our results suggest that glycerol application and the ssi2 mutation in various mutant backgrounds produce similar effects and that restoration of ssi2 phenotypes is not associated with the further desaturation of 18:1 to linoleic or linolenic acids in plastidal or extraplastidal lipids

Methodological approaches for estimating populations of the endangered dhole <i>Cuon alpinus</i>

Large carnivores are important for maintaining ecosystem integrity and attract much research and conservation interest. For most carnivore species, estimating population density or abundance is challenging because they do not have unique markings for individual identification. This hinders status assessments for many threatened species, and calls for testing new methodological approaches. We examined past efforts to assess the population status of the endangered dhole (Cuon alpinus), and explored the application of a suite of recently developed models for estimating their populations using camera-trap data from India’s Western Ghats. We compared the performance of Site-Based Abundance (SBA), Space-to-Event (STE), and Time-to-Event (TTE) models against current knowledge of their population size in the area. We also applied two of these models (TTE and STE) to the co-occurring leopard (Panthera pardus), for which density estimates were available from Spatially Explicit Capture–Recapture (SECR) models, so as to simultaneously validate the accuracy of estimates for one marked and one unmarked species. Our review of literature (n = 38) showed that most assessments of dhole populations involved crude indices (relative abundance index; RAI) or estimates of occupancy and area of suitable habitat; very few studies attempted to estimate populations. Based on empirical data from our field surveys, the TTE and SBA models overestimated dhole population size beyond ecologically plausible limits, but the STE model produced reliable estimates for both the species. Our findings suggest that it is difficult to estimate population sizes of unmarked species when model assumptions are not fully met and data are sparse, which are commonplace for most ecological surveys in the tropics. Based on our assessment, we propose that practitioners who have access to photo-encounter data on dholes across Asia test old and new analytical approaches to increase the overall knowledge-base on the species, and contribute towards conservation monitoring of this endangered carnivore