Chemoproteomics Reveals the Pan-HER Kinase Inhibitor Neratinib To Target an Epoxide Hydrolase Related to Phytohormone Signaling.

Plant phytohormone pathways are regulated by an intricate network of signaling components and modulators, many of which still remain unknown. Here, we report a forward chemical genetics approach for the identification of functional SA agonists in that revealed Neratinib (), a covalent pan-HER kinase inhibitor drug in humans, as a modulator of SA signaling. Instead of a protein kinase, chemoproteomics unveiled that covalently modifies a surface-exposed cysteine residue of epoxide hydrolase isoform 7 (AtEH7), thereby triggering its allosteric inhibition.

Inhibition of jasmonate-mediated plant defences by the fungal metabolite higginsianin B.

Infection of Arabidopsis thaliana by the ascomycete fungus Colletotrichum higginsianum is characterized by an early symptomless biotrophic phase followed by a destructive necrotrophic phase. The fungal genome contains 77 secondary metabolism-related biosynthetic gene clusters, whose expression during the infection process is tightly regulated. Deleting CclA, a chromatin regulator involved in the repression of some biosynthetic gene clusters through H3K4 trimethylation, allowed overproduction of three families of terpenoids and isolation of 12 different molecules.

Plant chemical genetics reveals colistin sulphate as a SA and NPR1-independent PR1 inducer functioning via a p38-like kinase pathway.

In plants, low-dose of exogenous bacterial cyclic lipopeptides (CLPs) trigger transient membrane changes leading to activation of early and late defence responses. Here, a forward chemical genetics approach identifies colistin sulphate (CS) CLP as a novel plant defence inducer. CS uniquely triggers activation of the PATHOGENESIS-RELATED 1 (PR1) gene and resistance against Pseudomonas syringae pv.

Identification of the Natural Product Rotihibin A as a TOR Kinase Signaling Inhibitor by Unbiased Transcriptional Profiling.

Bioactive natural products are important starting points for developing chemical tools for biological research. For elucidating their bioactivity profile, biological systems with concise complexity such as cell culture systems are frequently used, whereas unbiased investigations in more complex multicellular systems are only rarely explored. Here, we demonstrate with the natural product Rotihibin A and the plant research model system Arabidopsis thaliana that unbiased transcriptional profiling enables a rapid, label-free, and compound economic evaluation of a natural product's bioactivity profile in a complex multicellular organism.

Chemical Activation of EDS1/PAD4 Signaling Leading to Pathogen Resistance in Arabidopsis.

In a chemical screen we identified thaxtomin A (TXA), a phytotoxin from plant pathogenic Streptomyces scabies, as a selective and potent activator of FLAVIN-DEPENDENT MONOOXYGENASE1 (FMO1) expression in Arabidopsis (Arabidopsis thaliana). TXA induction of FMO1 was unrelated to the production of reactive oxygen species (ROS), plant cell death or its known inhibition of cellulose synthesis. TXA-stimulated FMO1 expression was strictly dependent on ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4) but independent of salicylic acid (SA) synthesis via ISOCHORISMATE SYNTHASE1 (ICS1).

High-Throughput Screening of Chemical Compound Libraries for Modulators of Salicylic Acid Signaling by In Situ Monitoring of Glucuronidase-Based Reporter Gene Expression.

Salicylic acid (SA) is a vital phytohormone that is intimately involved in coordination of the complex plant defense response to pathogen attack. Many aspects of SA signaling have been unraveled by classical genetic and biochemical methods using the model plant Arabidopsis thaliana, but many details remain unknown, owing to the inherent limitations of these methods. In recent years, chemical genetics has emerged as an alternative scientific strategy to complement classical genetics by virtue of identifying bioactive chemicals or probes that act selectively on their protein targets causing either activation or inhibition.

The Root Growth-Regulating Brevicompanine Natural Products Modulate the Plant Circadian Clock.

Plant growth regulating properties of brevicompanines (Brvs), natural products of the fungus Penicillium brevicompactum, have been known for several years, but further investigations into the molecular mechanism of their bioactivity have not been performed. Following chemical synthesis of brevicompanine derivatives, we studied their activity in the model plant Arabidopsis by a combination of plant growth assays, transcriptional profiling, and numerous additional bioassays. These studies demonstrated that brevicompanines cause transcriptional misregulation of core components of the circadian clock, whereas other biological read-outs were not affected.

Colletotrichum higginsianum extracellular LysM proteins play dual roles in appressorial function and suppression of chitin-triggered plant immunity.

The genome of the hemibiotrophic anthracnose fungus, Colletotrichum higginsianum, encodes a large repertoire of candidate-secreted effectors containing LysM domains, but the role of such proteins in the pathogenicity of any Colletotrichum species is unknown. Here, we characterized the function of two effectors, ChELP1 and ChELP2, which are transcriptionally activated during the initial intracellular biotrophic phase of infection. Using immunocytochemistry, we found that ChELP2 is concentrated on the surface of bulbous biotrophic hyphae at the interface with living host cells but is absent from filamentous necrotrophic hyphae.

Facile high-throughput forward chemical genetic screening by in situ monitoring of glucuronidase-based reporter gene expression in Arabidopsis thaliana.

The use of biologically active small molecules to perturb biological functions holds enormous potential for investigating complex signaling networks. However, in contrast to animal systems, the search for and application of chemical tools for basic discovery in the plant sciences, generally referred to as "chemical genetics," has only recently gained momentum. In addition to cultured cells, the well-characterized, small-sized model plant Arabidopsis thaliana is suitable for cultivation in microplates, which allows employing diverse cell- or phenotype-based chemical screens.