Biology subjects

Hammerl, R.

Publications and source records attributed to Hammerl, R..

3 recordsLinked to original sources

bioRxiv2021

Intraspecific diversity observed in the wild tomato species Solanum chilense in initial immune responses towards a glucan elicitor.

Natural plant populations are polymorphic and show intraspecific variation in resistance properties against pathogens. The activation of the underlying defence responses can depend on variation in perception of pathogen-associated molecular patterns or elicitors. To dissect such variation, we evaluated the responses induced by laminarin, (a glucan, representing an elicitor from oomycetes) in the wild tomato species Solanum chilense and correlated this to observed infection frequencies of Phytophthora infestans. We measured reactive oxygen species burst and levels of diverse phytohormones upon elicitation in 83 plants originating from nine populations. We found high diversity in basal and elicitor-induced levels of each component. Further we generated linear models to explain the observed infection frequency of P. infestans. The effect of individual components differed dependent on the geographical origin of the plants. We found that the resistance in the southern coastal region, but not in the other regions is directly correlated to ethylene responses and confirmed this positive correlation using ethylene inhibition assays. Our findings reveal high diversity in the strength of defence responses within a species and the involvement of different components with a quantitatively different contribution of individual components to resistance in geographically separated populations of a wild plant species. HighlightLarge-scale screenings reveal geographically distinct intraspecific differences in the dominant physiological pathogen defence responses upon glucan elicitor treatment in a wild tomato species.

plant biology↗

bioRxiv2021

Local jasmonic acid cues drive systemic acquired resistance signal generation

The phytohormones salicylic acid (SA) and jasmonic acid (JA) promote two, mutually antagonistic immune pathways respectively protecting plants from biotrophic pathogens and necrotrophic pathogens or insects. This trade-off largely precludes the exploitation of SA and JA immune components for crop protection, raising the interest in immune signalling components that disrupt SA-JA antagonism. A local pathogen infection primes SA-dependent immunity in systemic tissues. This so-called systemic acquired resistance (SAR) ensures a long-lasting, broad-spectrum disease resistance that is not subject to SA-JA antagonism. Here, we show that two sequence-related LEGUME LECTIN-LIKE PROTEINs (LLPs) promote SAR through spatially separated functions with JA promoting local SAR signal generation through LLP3. In concert with LLP1, which is important for systemic recognition and propagation of SAR signals, LLP3 promotes both SA-dependent SAR and JA-mediated immunity. Thus, exploitation of LLP-associated signalling cues might allow application of plant innate immune signals to promote (crop) plant health.

plant biology↗

bioRxiv2019

The Arabidopsis receptor kinase STRUBBELIG regulates the response to cellulose deficiency

Plant cells are encased in a semi-rigid cell wall of complex build. As a consequence, cell wall remodeling is essential for the control of growth and development as well as the regulation of abiotic and biotic stress responses. Plant cells actively sense physico-chemical changes in the cell wall and initiate corresponding cellular responses. However, the underlying cell wall monitoring mechanisms remain poorly understood. In Arabidopsis the atypical receptor kinase STRUBBELIG (SUB) mediates tissue morphogenesis. Here, we show that SUB-mediated signal transduction also regulates the cellular response to a reduction in the biosynthesis of cellulose, a central carbohydrate component of the cell wall. SUB signaling affects early increase of intracellular reactive oxygen species, stress gene induction as well as ectopic lignin and callose accumulation upon exogenous application of the cellulose biosynthesis inhibitor isoxaben. Moreover, our data reveal that SUB signaling is required for maintaining cell size and shape of root epidermal cells and the recovery of root growth after transient exposure to isoxaben. SUB is also required for root growth arrest in mutants with defective cellulose biosynthesis. Genetic data further indicate that SUB controls the isoxaben-induced cell wall stress response independently from other known receptor kinase genes mediating this response, such as THESEUS1 or MIK2. We propose that SUB functions in a least two distinct biological processes: the control of tissue morphogenesis and the response to cell wall damage. Taken together, our results reveal a novel signal transduction pathway that contributes to the molecular framework underlying cell wall integrity signaling.\n\nAuthor SummaryPlant cells are encapsulated by a semi-rigid and biochemically complex cell wall. This particular feature has consequences for multiple biologically important processes, such as cell and organ growth or various stress responses. For a plant cell to grow the cell wall has to be modified to allow cell expansion, which is driven by outward-directed turgor pressure generated inside the cell. In return, changes in cell wall architecture need to be monitored by individual cells, and to be coordinated across cells in a growing tissue, for an organ to attain its regular size and shape. Cell wall surveillance also comes also into play in the reaction against certain stresses, including for example infection by plant pathogens, many of which break through the cell wall during infection, thereby generating wall-derived factors that can induce defense responses. There is only limited knowledge regarding the molecular system that monitors the composition and status of the cell wall. Here we provide further insight into the mechanism. We show that the cell surface receptor STRUBBELIG, previously known to control organ development in Arabidopsis, also promotes the cells response to reduced amounts of cellulose, a main component of the cell wall.

plant biology↗