Charakterisierung und Nutzung von bakteriellen Quorum Sensing Molekülen für die Weiterentwicklung eines umweltgerechten Pflanzenbaus

Die Aktivierung und Stärkung des pflanzlichen Immunsystems ist eine vielversprechende Alternative im Pflanzenschutz. Das Konzept umfasst eine Sensibilisierung (priming) der Kulturpflanzen gegenüber Pathogenen, die einen hohen Ernteertrag auch unter Pathogendruck gewährleistet. Bakterielle quorum sensing Moleküle haben die Eigenschaft, Pflanzen zu sensibilisieren und sind deshalb eine mögliche Ergänzung zum Einsatz von Pflanzenschutzmaßnahmen. Das Ziel dieses Vorhabens war es, Immunantwort und physiologische Veränderungen in wichtigen Kulturpflanzen, wie Gerste, Weizen, Tomaten und Luzerne nach einer Sensibilisierung mit QS Molekülen zu analysieren. Eingesetzt wurden einerseits langkettige Acyl-Homoserinlaktone, wie das oxo-C14-HSL, und andererseits nützliche, nicht-pathogene oxo-C14-HSL-produzierende Rhizobakterium, wie Sinorhizobium meliloti und Rhizobium radiobacter F4 (RrF4), das aus dem nützlichen Pilz Piriformospora indica isoliert wurde. Wir konnten eine oxo-C14-HSL-induzierte Resistenz von Arabidopsis Pflanzen demonstrieren und zeigen, dass diese Resistenzinduktion auf der Basis eines Salicylsäure/Oxylipin-abhängigen systemischen Signal generiert wird. Darüber hinaus bewirkt eine oxo-C14-HSL Behandlung bei Gerste und Weizen eine verstärkte Produktion von reaktiven Sauerstoffspezies und eine transkriptionelle Regulation verteidigungsrelevanter Genen. Die oxo-C14-HSL-induzierte Sensibilisierung bewirkt eine Verstärkung der Pflanzenzellwand und eine Abwehrreaktion in den Stomata, wodurch ein Eindringen von bakteriellen und pilzlichen Krankheitserregern und deren Proliferation in der Pflanze stark gehemmt werden. Zudem wurde überraschenderweise gefunden, dass oxo-C14-HSL auch die Vermehrung des humanpathogenen Erregers Salmonella enterica serovar Thyphimurium in Arabidopsis verhindert. Dieser Effekt war starker ausgeprägt bei direkter Behandlung mit oxo-C14-HSL, während eine Behandlung mit oxo-C14-HSL-produzierendem S. meliloti keine gute Wirkung gegen Salmonellen zeigte. Unsere Ergebnisse verdeutlichen, das bakterielle quorum sensing Moleküle eine positive Wirkung auf Pflanzen haben. Die hier beschriebene Acyl-Homoserinlakton-induzierte Resistenz (AIR) ist ein neues Modell zur pflanzlichen „Sensibilisierung“ für schnellere und stärkere Abwehrreaktionen auf künftige Stresssituationen und bahnt somit einen vielversprechenden Weg im modernen Pflanzenschutz

LNCS

Generalized Selective Decryption (GSD), introduced by Panjwani [TCC’07], is a game for a symmetric encryption scheme Enc that captures the difficulty of proving adaptive security of certain protocols, most notably the Logical Key Hierarchy (LKH) multicast encryption protocol. In the GSD game there are n keys k1,..., kn, which the adversary may adaptively corrupt (learn); moreover, it can ask for encryptions Encki (kj) of keys under other keys. The adversary’s task is to distinguish keys (which it cannot trivially compute) from random. Proving the hardness of GSD assuming only IND-CPA security of Enc is surprisingly hard. Using “complexity leveraging” loses a factor exponential in n, which makes the proof practically meaningless. We can think of the GSD game as building a graph on n vertices, where we add an edge i → j when the adversary asks for an encryption of kj under ki. If restricted to graphs of depth ℓ, Panjwani gave a reduction that loses only a factor exponential in ℓ (not n). To date, this is the only non-trivial result known for GSD. In this paper we give almost-polynomial reductions for large classes of graphs. Most importantly, we prove the security of the GSD game restricted to trees losing only a quasi-polynomial factor n3 log n+5. Trees are an important special case capturing real-world protocols like the LKH protocol. Our new bound improves upon Panjwani’s on some LKH variants proposed in the literature where the underlying tree is not balanced. Our proof builds on ideas from the “nested hybrids” technique recently introduced by Fuchsbauer et al. [Asiacrypt’14] for proving the adaptive security of constrained PRFs

Tamper Detection and Continuous Non-Malleable Codes

We consider a public and keyless code (\Enc,\Dec) which is used to encode a message $m$ and derive a codeword c = \Enc(m). The codeword can be adversarially tampered via a function f \in \F from some tampering function family \F, resulting in a tampered value $c\u27 = f(c)$. We study the different types of security guarantees that can be achieved in this scenario for different families \F of tampering attacks. Firstly, we initiate the general study of tamper-detection codes, which must detect that tampering occurred and output \Dec(c\u27) = \bot. We show that such codes exist for any family of functions \F over $n$ bit codewords, as long as |\F| < 2^{2^n} is sufficiently smaller than the set of all possible functions, and the functions f \in \F are further restricted in two ways: (1) they can only have a few fixed points $x$ such that $f(x)=x$, (2) they must have high entropy of $f(x)$ over a random $x$. Such codes can also be made efficient when |\F| = 2^{\poly(n)}. For example, \F can be the family of all low-degree polynomials excluding constant and identity polynomials. Such tamper-detection codes generalize the algebraic manipulation detection (AMD) codes of Cramer et al. (EUROCRYPT \u2708). Next, we revisit non-malleable codes, which were introduced by Dziembowski, Pietrzak and Wichs (ICS \u2710) and require that \Dec(c\u27) either decodes to the original message $m$, or to some unrelated value (possibly $\bot$) that doesn\u27t provide any information about $m$. We give a modular construction of non-malleable codes by combining tamper-detection codes and leakage-resilient codes. This gives an alternate proof of the existence of non-malleable codes with optimal rate for any family \F of size |\F| < 2^{2^n}, as well as efficient constructions for families of size |\F| = 2^{\poly(n)}. Finally, we initiate the general study of continuous non-malleable codes, which provide a non-malleability guarantee against an attacker that can tamper a codeword multiple times. We define several variants of the problem depending on: (I) whether tampering is persistent and each successive attack modifies the codeword that has been modified by previous attacks, or whether tampering is non-persistent and is always applied to the original codeword, (II) whether we can self-destruct and stop the experiment if a tampered codeword is ever detected to be invalid or whether the attacker can always tamper more. In the case of persistent tampering and self-destruct (weakest case), we get a broad existence results, essentially matching what\u27s known for standard non-malleable codes. In the case of non-persistent tampering and no self-destruct (strongest case), we must further restrict the tampering functions to have few fixed points and high entropy. The two intermediate cases correspond to requiring only one of the above two restrictions. These results have applications in cryptography to related-key attack (RKA) security and to protecting devices against tampering attacks without requiring state or randomness

Alternative oxidase involvement in Daucus carota somatic embryogenesis

Plant alternative oxidase (AOX) is a mitochondrial inner membrane enzyme involved in alternative respiration.The critical importance of the enzyme during acclimation upon stress of plant cells is not fully understood and is still an issue of intensive research and discussion. Recently, a role of AOX was suggested for the ability of plant cells to change easily its fate upon stress. In order to get new insights about AOX involvement in cell reprogramming, quantitative real-time polymerase chain reaction (PCR) and inhibitor studies were performed during cell redifferentiation and developmental stages of Daucus carota L. somatic embryogenesis. Transcript level analysis shows that D. carota AOX genes (DcAOX1a and DcAOX2a) are differentially expressed during somatic embryogenesis. DcAOX1a shows lower expression levels, being mainly down- regulated, whereas DcAOX2a presented a large up-regulation during initiation of the realization phase of somatic embryogenesis. However, when globular embryos start to develop, both genes are down-regulated, being this state transient for DcAOX2a. In addition, parallel studies were performed using salicylhydroxamic acid (SHAM) in order to inhibit AOX activity during the realization phase of somatic embryogenesis. Embryogenic cells growing in the presence of the inhibitor were unable to develop embryogenic structures and its growth rate was diminished. This effect was reversible and concentration dependent. The results obtained contribute to the hypothesis that AOX activity supports metabolic reorganization as an essential part of cell reprogramming and, thus, enables restructuring and de novo cell differentiation

Analysis and purification of ssRNA and dsRNA molecules using asymmetrical flow field flow fractionation

Robust RNA purification and analysis methods are required to support the development of RNA vaccines and therapeutics as well as RNA interference-based crop protection solutions. Asymmetrical flow field -flow fractionation (AF4) is a gentle native purification method that applies liquid flows to separate sample components based on their hydrodynamic sizes. We recently showed that AF4 can be utilized to separate RNA molecules that are shorter than 110 nucleotides (nt), but the performance of AF4 in the analysis and purification of longer RNA molecules has not been previously evaluated. Here, we studied the perfor-mance of AF4 in separation of single-stranded (ss) and double-stranded (ds) RNA molecules in the size range of 75-6400 nt. In addition, we evaluated the power of AF4 coupling to different detectors, allow-ing separation to be combined with data collection on yield as well as molecular weight ( MW ) and size distribution. We show that AF4 method is applicable in RNA purification, quality control, and analytics, and results in good recoveries of ssRNA and dsRNA molecules. In addition, our results demonstrate the utility of AF4 multidetection platforms to study biophysical properties of long RNA molecules.(c) 2022 The Author(s). Published by Elsevier B.V.This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )Peer reviewe

The Relationship between Non-Financial Stakeholders and Capital Structure

In today's dynamic environment, both intellectual capital (IC), the main value added factor, and perceived environmental uncertainty (PEU), an unpredictable contingency factor, influence corporate performance (CP). Financial accounting literature highlights the importance of non-financial factors. Therefore, it is important for organizations to rely more on non-financial criteria than on financial factors to achieve higher competitive advantage. Identifying the most important non-financial factors that affect corporate performance and their relationship with capital structures (CS) is the main issue in today's dynamic conditions. This research examines the relationship between non-financial factors of IC and PEU and evaluates their influence on CS directly or indirectly by considering the mediation effects of corporate performance. Questionnaires were distributed to 339 public listed Iranian manufacturing companies selected based on census data. Data was analyzed using structural equation modeling. The main findings of this study are as follows: IC can enhance corporate performance, PEU is positively linked to corporate performance, and corporate performance is positively linked to capital structure. The results also indicated a full mediation effect of corporate performance in the relationship between PEU and capital structure. Also, we analyze intellectual capital relation with 1) traditional vs. secular-rational values and with 2) survival vs. self-expression values. In order to determine the most efficient versions of intellectual capital, an Intellectual Capital Multiple Criteria Decision Support (ICMCDS) system was developed, consisting of a database, database management system, model-base, model-base management system, and user interface. This study contributes to determining capital structure decision making by considering IC and PEU in the context of companies in Iran. Further in-depth research is needed to examine the links between non-financial factors and capital structure with different measurement and perspectives to develop a deeper understanding of their effect on capital structure