Publikationen - Molekulare Signalverarbeitung

Leaf epidermis pavement cells develop complex jigsaw puzzle-like shapes in many plant species, including the model plant Arabidopsis thaliana. Due to their complex morphology, pavement cells have become a popular model system to study shape formation and coordination of growth in the context of mechanically coupled cells at the tissue level. To facilitate robust assessment and analysis of pavement cell shape characteristics in a high-throughput fashion, we have developed PaCeQuant and a collection of supplemental tools. The ImageJ-based MiToBo plugin PaCeQuant supports fully automatic segmentation of cell contours from microscopy images and the extraction of 28 shape features for each detected cell. These features now also include the Largest Empty Circle criterion as a proxy for mechanical stress. In addition, PaCeQuant provides a set of eight features for individual lobes, including the categorization as type I and type II lobes at two- and three-cell junctions, respectively. The segmentation and feature extraction results of PaCeQuant depend on the quality of input images. To allow for corrections in case of local segmentation errors, the LabelImageEditor is provided for user-friendly manual postprocessing of segmentation results. For statistical analysis and visualization, PaCeQuant is supplemented with the R package PaCeQuantAna, which provides statistical analysis functions and supports the generation of publication-ready plots in ready-to-use R workflows. In addition, we recently released the FeatureColorMapper tool which overlays feature values over cell regions for user-friendly visual exploration of selected features in a set of analyzed cells.

Jasmonates are essential engineers of plant defense responses against many pests, including herbivorous insects. Herbivory induces the production of jasmonic acid (JA) and its bioactive conjugate jasmonoyl-l-isoleucine (JA-Ile), which then triggers a large transcriptional reprogramming to promote plant acclimation. The contribution of the JA pathway, including its components and regulators, to defense responses against insect herbivory can be evaluated by conducting bioassays with a wide range of host plants and insect pests. Here, we describe a detailed and reproducible protocol for testing feeding behavior of the generalist herbivore Spodoptera littoralis on the model plant Arabidopsis thaliana and hence infer the contribution of JA-mediated plant defense responses to a chewing insect.

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The definition of a plant hormone has not been clearly established, so the compounds classified as plant hormones often vary depending on which definition is considered. In this chapter, auxins, gibberellins (GAs), cytokinins, abscisic acid, brassinosteroids, jasmonic acid-related compounds, and ethylene are described as established plant hormones, while polyamines and phenolic compounds are not included. On the other hand, several peptides that have been proven to play a clear physiological role(s) in plant growth and development, similar to the established plant hormones, are referred. This chapter will focus primarily on the more recent discoveries of plant hormones and their impact on our current understanding of their biological role. In some cases, however, it is critical to place recent work in a proper historical context.

This chapter contains sections titled:IntroductionJA BiosynthesisJA MetabolismBound OPDA – ArabidopsidesMutants of JA Biosynthesis and SignalingCOI1–JAZ–JA‐Ile‐Mediated JA SignalingTranscription Factors Involved in JA SignalingJasmonates and Oxylipins in DevelopmentConclusionsAcknowledgmentsReferences

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