HarpinPss, a proteinaceous elicitor from Pseudomonas syringae pv. syringae, is a glycine-rich, cysteine-lacking, heat-stable protein. It can elicit the hypersensitive response (HR) when delivered to the surface of plant cells. HRAP (hypersensitive response assisting protein) is an amphipathic protein purified from sweet pepper and could intensify harpinPss¡Vmediated HR in sweet pepper. In the previous research, harpinPss was present as monomer, dimer, trimer, tetramer, and ocatamer forms in neutral pH buffer. Only monomer and dimer forms of harpinPss induced hypersensitive response in nonhost plants. HRAP could cause multimeric forms of harpinPss dissociation into monomer forms. The interaction between HRAP and harpinPss is an important issue. HRAP contained three positively charged regions, a typical signal peptide and a cAMP-dependent phosphorylation site. In this study, these regions of HRAP would be truncated and identified whether these truncated HRAP fragments could promote harpinPss dissociation. Different combinations of truncated HRAP and harpinPss were used to identify the protein-interaction regions between two proteins. HarpinPss triggers HR via interaction with cAMP phosphorated region of HRAP and MAPK pathway transduction. When cAMP region of HRAP was truncated, harpinPss still triggers HR via polymerization and anchor on lipid bilayers to form an ion-conducting pore.

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In our investigation, fully expanded tobacco leaves were used to study the hypersensitive response caused by the inoculation of INF1 purified from E. coli strains DH5£\

Infection of fully expanded leaves of tobacco with INF1 causes the appearance of HR lesions within 12 h and progressive to all infection sites after 48 h treatment. Among the POD isozymes, the increase of cationic PODs and anionic PODs is correlated with the rise of lignin contents in INF1-treated leaves, especially cationic PODs (pI 9.5, pI 8.7, pI 8.3, pI 7.8, pI 7.4). It was suggested that the induction of POD activity resulted in part of H2O2 reduction. The increase of cationic (pI 9.5) and anionic (pI 4.4) POD transcripts was correlated with the increased cationic and anionic PODs activity in INF1-treated leaves. Therefore, the increased POD activity is due to the de novo synthesis of the cationic (pI 9.5) and anionic (pI 4.4) PODs in INF1-treated leaves. The increase in cationic pI 9.6 laccase transcript was also correlated with the increased cationic laccase activity in INF1-treated leaves. Our results suggest that laccase might play a major role on lignin biosynthesis at the early stage (6 h), and as the inoculation time was prolonged, peroxidases (especially cationic POD) and laccases will work together on lignin biosynthesis.

Harpinpss, a pathogenic protein, encoded by hrpZ in the hrp gene cluster from Pswudomonas syringae pv. syringae, can induce the hypersensitive response in tobacco (Nicotiana tabacum L. cv. Xanthi). The lesion area on the tobacco leaves was visible 6 h after inoculation with harpin, and was evident 12 h after inoculation. The lignin content in harpin-treated tobacco leaves was about 2.5-fold as compared with the controls 24 h after inoculation. There were six isozymes of POD (pI 9.5, pI 8.7, pI 5.3, pI 4.4, pI 3.7, and pI 3.5) and seven isozymes of laccase (pI 9.4, pI 8.6, pI 7.8, pI 5.4, pI 4.5, pI 3.8, and pI 3.6) identified by isoelectric point in extracts of harpin-inoculated tobacco leaves. POD isozymes (pI 4.4, pI 5.3 and pI 8.7) and laccase isozyme (pI 7.8) only appeared in harpin-inoculated tissues. The increased POD isozymes (pI 4.4, pI 8.7, pI 9.5) are correlated with the rise of transcripts of these enzymes confirmed by the method of reverse transcriptase-polymerase chain reaction (RT-PCR).

Plants defence responses are often associated with the development of the so-called hypersensitive response (HR), a form of PCD that confines the pathogen to the infection site. The sharp boundary of the HR suggests the existence of efficient mechanisms that control cell death and survival. The Arabidopsis transcription factor AtMYB30 positively regulates plant defence and HR responses by enhancing the synthesis of sphingolipid-containing Very Long Chain Fatty Acids (VLCFA) after bacterial infection. The activity of AtMYB30 is tightly controlled inside plant cells through protein-protein interactions and post-translational modifications. During my PhD, we identified a protease of the subtilase family (AtSBT5.2) as a AtMYB30-interacting partner. Interestingly, we have shown that the AtSBT5.2 transcript is alternatively spliced, leading to the production of two distinct gene products that encode either a secreted [AtSBT5.2(a)] or an intracellular [AtSBT5.2(b)] protein. The specific interaction between AtMYB30 and AtSBT5.2(b), but not AtSBT5.2(a), leads to AtMYB30 specific retention outside of the nucleus in small intracellular vesicles. atsbt5.2 Arabidopsis mutant plants, in which both AtSBT5.2(a) and AtSBT5.2(b) expression was abolished, displayed enhanced HR and defence responses. The fact that this phenotype is abolished in an atmyb30 mutant background suggests that AtSBT5.2 is a negative regulator of AtMYB30-mediated disease resistance. Importantly, overexpression of the AtSBT5.2(b), but not the AtSBT5.2(a), isoform in the atsbt5.2 mutant background reverts the phenotypes displayed by atsbt5.2 mutant plants, suggesting that AtSBT5.2(b) specifically represses AtMYB30-mediated defence.

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Why is it that we humans have a tendency to construct transcendental entities? That is one of the big questions the scientific discipline Cognitive Science of Religion is trying to answer. In order to gain validation for the concepts used by this discipline neural correlates are needed. The aim of the present work is to investigate the concepts Hypersensitive Agency Detection Device ((H)ADD) and Theory of Mind (ToM) both in psychological, cognitive and neural aspects to see if those concepts are enough to explain the human tendencies to construct transcendental entities. This work is developed as philosophical a literature study and uses literature from the scientific disciplines of cognitive neuroscience, cognitive science of religion, cognitive science, neurotheology, psychology of religion and philosophy of religion. This means that the present work is interdisciplinary and stands on a bridge between the theoretical and empirical sciences. A word of caution: Regardless the findings this work presents, the explanatory value is limited as it is a theoretical study in an empirical scientific field. It is when the findings in this work are tested empirically that the findings sustainability are decided.              What this work shows is that neural correlates for ToM already exist in the form of the Mirror Neuron-Theory (MNT), but it is problematic because it can not show how higher orders of representations are possible. No scientific data about neural correlates to (H)ADD has been found for this study, but here the amygdala may play a prominent role. Furthermore this work shows that (H)ADD and ToM is not enough to explain why humans have a tendency to construct transcendental entities. We are in need of peripheral cognitive mechanisms such as intuitive knowledge modules, ontological categories, teleological thinking, our drive to seek causal connections and our ability for pattern recognition.

Infection of the resistant Arabidopsis ecotype Di-17 with Turnip Crinkle Virus (TCV) elicits hypersensitive response (HR), accompanied by increased expression of defense genes. HR to TCV is conferred by HRT, which encodes a coiled-coil (CC)-nucleotide-binding site (NBS)-leucine-rich repeat (LRR) class of resistance (R) protein. In contrast to HR, resistance requires HRT and a recessive locus designated rrt. Unlike most CC-NBS-LRR R proteins, HRT-mediated resistance is dependent on EDS1 and independent of NDR1. Resistance is also dependent on salicylic acid (SA) pathway and light. A dark treatment, immediately following TCV inoculation, suppresses HR, resistance and activation of a majority of the TCV-induced genes. To determine the genetic, molecular and biochemical basis of light-dependent defense pathway, we studied the role of various photoreceptors in HRT-mediated resistance to TCV, HRT protein levels and its localization. Interestingly, mutation in blue-light photoreceptors led to degradation of HRT via a proteasome-dependent pathway and resulted in susceptibility to TCV. Exogenous application of SA induced transcription of HRT, which restored HRT levels in some, but not all, mutant backgrounds. These results show that different photoreceptors function distinctly in maintaining post-transcriptional stability of HRT. In addition to photoreceptors, HRT also forms a complex with several other proteins, many of which participate in the RNA silencing pathway and are required for HRT-mediated resistance. Together, our results suggest that HRT forms a multi-protein complex and that HRT-mediated signaling involves reconstitution of this complex.

Master of Science / Genetics Interdepartmental Program - Plant Pathology / Frank F. White / Sanzhen Liu / Plants and bacterial pathogens are in constant co-evolution to survive and sustain the next generation. Plants have two well-characterized levels of active defense -pathogens-associated molecular patterns (PAMPs)-triggered immunity (PTI) and effectors-triggered immunity (ETI). Some plants that are hosts for bacterial pathogens employing type three secretion system transcription activator-like (TAL) effectors have evolved a unique form of ETI, namely TAL effector-mediated ETI. TAL effectors induce expression of specific disease susceptibility (S) genes. Rice and pepper have evolved resistance genes termed terminator (T) genes, which have promoters that bind TAL effectors and, upon expression of the T gene, elicit a hypersensitive reaction (HR) and cell death. Only five T genes have been cloned, and the origin of most T genes is unknown. To determine the presence of candidate T genes in other plants species, a bioinformatics-based mining was designed. The basic approach utilized three structural features common to four terminator genes: a short trans-membrane domain, a secretion signal domain, and a length of <200 amino acid residues. Soybean was chosen as the test plant species, and 161 genes were retrieved that fulfilled the three parameters using R and Perl software programs. Further, functional annotation of candidate genes was conducted by comparisons to genes in public databases. Major classes of proteins found included unique and hypothetical, defense/stress/oxidative stress associated, DNA-binding, kinases, transferases, hydrolases, effector-related tRNA splicing, and F- box domain proteins. The potential T genes will serve as candidates for experimental validation and new resources for durable resistance strategies in crop species.