Exploring plant tolerance to biotic and abiotic stresses

Plants are exposed to many stress factors, such as drought, high salinity or pathogens, which reduce the yield of the cultivated plants or affect the quality of the harvested products. Arabidopsis thaliana was used as a model plant to study the responses of plants to different sources of stress. With Agrobacterium T-DNA mediated promoter tagging, a novel di-/tripeptide transporter gene AtPTR3 was identified as a wound-induced gene. This gene was found to be induced by mechanical wounding, high salt concentrations, bacterial infection and senescence, and also in response to several plant hormones and signalling compounds, such as salicylic acid, jasmonic acid, ethylene and abscisic acid. Atptr3 mutants of two Arabidopsis ecotypes, C24 and Col-0, were impaired in germination on media containing a high salt concentration, which indicates that AtPTR3 is involved in seed germination under salt stress. Wounding caused local expression of the AtPTR3 gene, whereas inoculation with the plant pathogenic bacterium Erwinia carotovora subsp. carotovora caused both local and systemic expression of the gene. Atptr3 mutants showed increased susceptibility to infection caused by bacterial phytopathogens, E carotovora and Pseudomonas syringae pv. tomato, and the P. syringae type III secretion system was shown to be involved in suppression of the AtPTR3 expression in inoculated plants. Moreover, the Atptr3 mutation was found to reduce the expression of the marker gene for systemic acquired resistance, PR1 and the mutants accumulated reactive oxygen species (ROS) following the treatment of the plants with ROS generating substances. Overall results and observations suggest that the AtPTR3 is a novel and versatile stress responsive gene needed for defence reactions against many stresses. In a second part of the study, the yeast (Saccharomyces cerevisiae) trehalose-6-phosphate synthase gene (ScTPS1) was utilized to improve the drought tolerance of Arabidopsis. This gene codes for the first enzyme in the trehalose biosynthesis pathway of yeast, and expression in plants leads to improved drought tolerance but also growth aberrations. In this study, the ScTps1 protein was expressed in Arabidopsis using the constructs containing chloroplast targeting transit peptide sequence that facilitated the import of the ScTps1 into the chloroplast. The drought tolerance and growth phenotypes of Arabidopsis transgenics transformed with ScTPS1 with or without transit peptide, were characterized. The plants with cytosolic localization of the ScTps1 protein showed aberrant root phenotype, but the plants with the chloroplast targeted ScTps1 protein caused no aberration in root morphology. Even though both the transgenic lines showed enhanced drought tolerance, the relative water content of the lines was found to be similar to the wild type control. Moreover, both the transgenic lines showed slightly better water holding capacity or reduced water loss over time compared to wild type plants. The overall results indicated that the growth aberrations caused by cytosolic localization of ScTps1 could be uncoupled from the enhanced drought tolerance in the transgenic plants when the ScTps1 was targeted to chloroplast

Enhancing Data Security for Cloud Computing Applications through Distributed Blockchain-based SDN Architecture in IoT Networks

Blockchain (BC) and Software Defined Networking (SDN) are some of the most prominent emerging technologies in recent research. These technologies provide security, integrity, as well as confidentiality in their respective applications. Cloud computing has also been a popular comprehensive technology for several years. Confidential information is often shared with the cloud infrastructure to give customers access to remote resources, such as computation and storage operations. However, cloud computing also presents substantial security threats, issues, and challenges. Therefore, to overcome these difficulties, we propose integrating Blockchain and SDN in the cloud computing platform. In this research, we introduce the architecture to better secure clouds. Moreover, we leverage a distributed Blockchain approach to convey security, confidentiality, privacy, integrity, adaptability, and scalability in the proposed architecture. BC provides a distributed or decentralized and efficient environment for users. Also, we present an SDN approach to improving the reliability, stability, and load balancing capabilities of the cloud infrastructure. Finally, we provide an experimental evaluation of the performance of our SDN and BC-based implementation using different parameters, also monitoring some attacks in the system and proving its efficacy.Comment: 12 Pages 16 Figures 3 Table

Multidrug-resistant non-typhoidal Salmonella of public health significance recovered from migratory birds in Bangladesh

Non-typhoidal Salmonella provides an exemplar for the One Health approach as it encompasses public and animal health, food safety, and environmental considerations. The contribution of environmental aspects is currently less well-defined. The purpose of this study was to determine the carriage occurrence of non-typhoidal Salmonella in migratory birds in Bangladesh and assess the potential significance to public and animal health. Cloacal swabs (N = 453) were collected in the years 2018-2020 from Tanguar and Hakaluki Haors, important wetland ecosystems in Northeastern Bangladesh. The prevalence of Salmonella was 13.5% (61 positive swabs). Classical serotyping identified six serovars: Salmonella enterica subsp. enterica serovars Perth, Kentucky, Albany, Infantis, Weltevreden, and Brancaster. Resistance towards 14 antimicrobials was assessed by broth microdilution minimum inhibitory concentration determination and the antimicrobial resistance (AMR) genotype established by whole-genome sequencing. S. Perth and S. Weltevreden isolates were susceptible and harbored no acquired AMR genes. Isolates from the remaining serovars were multidrug resistant, commonly possessing resistance to tetracycline, ampicillin, chloramphenicol, sulfamethoxazole, trimethoprim, and ciprofloxacin. Salmonella resistant to ciprofloxacin meets WHO criteria for priority pathogens. There was excellent concordance between resistance phenotype and the presence of corresponding AMR genes, many of which reside on Salmonella Genomic Islands. High-level ciprofloxacin resistance correlated with the presence of mutations in the chromosomal gyrB and/or parC genes. The S. Kentucky isolates were ST198, a widely distributed multidrug-resistant lineage reported in humans and animals, and constituting an ongoing risk to public health worldwide. We have demonstrated that multidrug-resistant non-typhoidal Salmonella of public health significance can be recovered from migratory birds. A potential for risk can manifest through direct interaction, transmission to food-producing livestock on farms, and dissemination via the long range migratory movements of birds. Risks can be mitigated by measures including continued surveillance and implementation of good farm biosecurity practices

Coping strategies and health-related quality of life in children and adolescents with type 1 diabetes

The aim of this study was to identify relationships between coping strategies and different aspects of health-related quality of life in children with type 1 diabetes measured with the Croatian translation of the PedsQL 4.0 Generic Core Scales and PedsQL Diabetes Module. The sample consisted of 199 schoolchildren: 47 patients with type 1 diabetes and 152 healthy children. Children health problems were rated with PedsQL 4.0 Generic Core Scale and with PedsQL Diabetes Module. Coping strategies were measured with The Coping Strategies Inventory for Children and Adolescents. The results showed that all subscales of the PedsQL 4.0 Generic Core Scales and the PedsQL Diabetes Module have satisfactory reliability with the majority of scales exceeding a Cronbach α of 0,70. Significant correlations were found between coping strategies and different aspects of health-related quality of life and those correlations were higher in girls than in boys. The findings of the present study suggest that child psychologists and clinicians treating children and adolescents suffering diabetes should address coping strategies related to specific health-related problems and assist them in developing more effective ways of coping

Endogenous indole-3-acetamide levels contribute to the crosstalk between auxin and abscisic acid, and trigger plant stress responses in Arabidopsis

Centro de Biotecnología y Genómica de Plantas (CBGP)The evolutionary success of plants relies to a large extent on their extraordinary ability to adapt to changes in their environment. These adaptations require that plants balance their growth with their stress responses. Plant hormones are crucial mediators orchestrating the underlying adaptive processes. However, whether and how the growth-related hormone auxin and the stress-related hormones jasmonic acid, salicylic acid, and abscisic acid (ABA) are coordinated remains largely elusive. Here, we analyse the physiological role of AMIDASE 1 (AMI1) in Arabidopsis plant growth and its possible connection to plant adaptations to abiotic stresses. AMI1 contributes to cellular auxin homeostasis by catalysing the conversion of indole-acetamide into the major plant auxin indole-3-acetic acid. Functional impairment of AMI1 increases the plant's stress status rendering mutant plants more susceptible to abiotic stresses. Transcriptomic analysis of ami1 mutants disclosed the reprogramming of a considerable number of stress-related genes, including jasmonic acid and ABA biosynthesis genes. The ami1 mutants exhibit only moderately repressed growth but an enhanced ABA accumulation, which suggests a role for AMI1 in the crosstalk between auxin and ABA. Altogether, our results suggest that AMI1 is involved in coordinating the trade-off between plant growth and stress responses, balancing auxin and ABA homeostasis.This research was supported by grants from the German Research Foundation (DFG, SFB480/A10) and the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, BFU2017-82826-R to SP and a grant from the Swedish Research Council (VR) to HA. JM was supported by the ‘Severo Ochoa Program for Centers of Excellence in R&D’ from the Agencia Estatal de Investigación of Spain, grant SEV-2016-0672 (2017-2021) to the CBGP.Peer reviewed17 Pág

Arabidopsis RabF1 (ARA6) Is Involved in Salt Stress and Dark-Induced Senescence (DIS)

Arabidopsis small GTPase RabF1 (ARA6) functions in endosomal vesicle transport and may play a crucial role in recycling and degradation of molecules, thus involved in stress responses. Here we have reported that complementary overexpression lines RabF1OE (overexpression), GTPase mutants RabF1Q93L (constitutively active) and RabF1S47N (dominant negative) lines show longer root growth than wild-type, rabF1 knockout and N-myristoylation deletion (Δ1−29, N-terminus) complementary overexpression mutant plants under salt induced stress, which indicates that N-myristoylation of RabF1 is indispensable for salt tolerance. Moreover, RabF1 is highly expressed during senescence and RabF1OE lines were more tolerant of dark-induced senescence (DIS) than wild-type and rabF1

Vesicle transport in chloroplasts with emphasis on Rab proteins

Chloroplasts perform photosynthesis using PSI and PSII during its light-dependent phase. Inside the chloroplast there is a membrane called thylakoid. The thylakoid membranes are an internal system of interconnected membranes that carry out the light reactions of photosynthesis. The thylakoid membranes do not produce their own lipids or proteins, so they are mainly transported from the envelope to the thylakoid for maintenance of e.g. the photosynthetic apparatus. An aqueous stroma made hinder between the envelope and thylakoid for the lipids to move between the two compartments. Vesicle transport is suggested to transport lipids to thylakoids supported by biochemical and ultra-structural data. Proteins could potentially also be transported by vesicles as cargo but this is not supported yet experimentally. However, proteins targeted to thylakoids are mediated by four pathways so far identified but it has been proposed that a vesicle transport could exist for proteins targeted to thylakoids as well similar to the cytosolic vesicle transport system. This thesis revealed similarity of vesicle transport inside the chloroplast to the cytosolic system. A novel Rab protein CPRabA5E (CP= chloroplast localized) was shown in Arabidopsis to be chloroplast localized and characterized to be important for thylakoid structure, plant development, and oxidative stress response. Moreover, CPRabA5e complemented the yeast homologues being involved in vesicle transport, and the cprabA5e mutants were affected for vesicle formation in the chloroplasts. Another Rab (CPRabF1) was also identified inside the chloroplast and could possibly play a role in vesicle transport. Interestingly, CPRabF1 has previously been characterized for its involvement in vesicle transport in the cytosol and thus its localization in chloroplasts might indicate dual targeting of CPRabF1. No phenotype was observed despite usage of several applied factors e.g. high light and osmotic stress. A previous bioinformatics study predicted several Rab related proteins inside chloroplasts linked to a suggested COPII vesicle transport system. We analyzed the gene expression for the Rab related genes at several developmental stages covering the life span of Arabidopsis e.g. from seedlings to senescence. The data indicated a rather homogenous expression pattern among the genes studied being around 20-60% expressed for all developmental stages except for senescence were the expression pattern was more discrete. At senescence chloroplast degradation occurs indicating less need for vesicle components. The idea of a COPII vesicle system inside chloroplast raised the question of a COPI or clathrin coated vesicle (CCV) system in chloroplasts. Through a bioinformatics approach we found several homologues of cytosolic COPI and CCV related vesicle transport components inside chloroplast. However, many of them already had a clear function other than vesicle transport or were having an unknown function. Moreover, many necessary subunits to build a functional COPI and CCV system were not even identified to be chloroplast localized and so we concluded that vesicle transport in chloroplast do not have strong similarities with a COPI or CCV system, rather being more linked to a COPII system as recently suggested

Monogalactosyldiacylglycerol Deficiency in Arabidopsis Affects Pigment Composition in the Prolamellar Body and Impairs Thylakoid Membrane Energization and Photoprotection in Leaves1[W][OA]

Monogalactosyldiacylglycerol (MGDG) is the major lipid constituent of chloroplast membranes and has been proposed to act directly in several important plastidic processes, particularly during photosynthesis. In this study, the effect of MGDG deficiency, as observed in the monogalactosyldiacylglycerol synthase1-1 (mgd1-1) mutant, on chloroplast protein targeting, phototransformation of pigments, and photosynthetic light reactions was analyzed. The targeting of plastid proteins into or across the envelope, or into the thylakoid membrane, was not different from wild-type in the mgd1 mutant, suggesting that the residual amount of MGDG in mgd1 was sufficient to maintain functional targeting mechanisms. In dark-grown plants, the ratio of bound protochlorophyllide (Pchlide, F656) to free Pchlide (F631) was increased in mgd1 compared to the wild type. Increased levels of the photoconvertible pigment-protein complex (F656), which is photoprotective and suppresses photooxidative damage caused by an excess of free Pchlide, may be an adaptive response to the mgd1 mutation. Leaves of mgd1 suffered from a massively impaired capacity for thermal dissipation of excess light due to an inefficient operation of the xanthophyll cycle; the mutant contained less zeaxanthin and more violaxanthin than wild type after 60 min of high-light exposure and suffered from increased photosystem II photoinhibition. This is attributable to an increased conductivity of the thylakoid membrane at high light intensities, so that the proton motive force is reduced and the thylakoid lumen is less acidic than in wild type. Thus, the pH-dependent activation of the violaxanthin de-epoxidase and of the PsbS protein is impaired

AtPTR3, a wound-induced peptide transporter needed for defence against virulent bacterial pathogens in Arabidopsis

Mutation in the wound-induced peptide transporter gene AtPTR3 (At5g46050) of Arabidopsis thaliana has been shown to affect germination on media containing a high salt concentration. The heterologous expression in yeast was utilized to verify that the AtPTR3 protein transports di-and tripeptides. The T-DNA insert in the Atptr3-1 mutant in the Arabidopsis ecotype C24 revealed two T-DNA copies, the whole vector sequence, and the gus marker gene inserted in the second intron of the AtPTR3 gene. An almost identical insertion site was found in the Atptr3-2 mutant of the Col-0 ecotype. The AtPTR3 expression was shown to be regulated by several signalling compounds, most clearly by salicylic acid (SA), but also methyl jasmonate (MeJA) and abscisic acid. Real-time PCR experiments suggested that the wound-induction of the AtPTR3 gene was abolished in the SA and JA signalling mutants. The Atptr3 mutant plants had increased susceptibility to virulent pathogenic bacteria Erwinia carotovora subsp. carotovora and Pseudomonas syringae pv. tomato, and produced more reactive oxygen species when grown on media containing paraquat or rose bengal. Public microarray data suggest that the AtPTR3 expression was induced by Pseudomonas elicitors and by avirulent P. syringae pathovars and type III secretion mutants. This was verified experimentally for the hrpA mutant with real-time PCR. These results suggest that AtPTR3 is one of the defence-related genes whose expression is reduced by virulent bacterium by type III dependent fashion. Our results suggest that AtPTR3 protects the plant against biotic and abiotic stresses