Publications by authors named "Merel Steenbergen"

5 Publications

  • Page 1 of 1

Bioassays to Evaluate the Resistance of Whole Plants to the Herbivorous Insect Thrips.

Methods Mol Biol 2020 ;2085:93-108

Plant-Microbe Interactions, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands.

Thrips are tiny, cell-content-feeding insects that are a major pest on crops and ornamentals. Besides causing direct feeding damage, thrips may also cause indirect damage by vectoring tospoviruses. Novel resistance mechanisms to thrips need to be discovered and validated. Induction of jasmonic acid-dependent defenses has been demonstrated to be essential for resistance to thrips, but underlying mechanisms still need to be discovered. For this, it is vital to use robust plant-thrips assays to analyze plant defense responses and thrips performance. In recently developed high-throughput phenotyping platforms, the feeding damage that is visible as silver spots, and the preference of thrips in a two-choice setup is assessed, using leaf discs. Here, we describe whole-plant thrips assays that are essential for (1) validation of findings obtained by the leaf disc assays, (2) assessment of longer-term effects on thrips feeding success and fecundity, (3) determination of spatial-temporal effects induced by primary thrips infestation on a secondary attack by thrips or other insects or pathogens, and (4) assessment of gene expression and metabolite changes. We present detailed methods and tips and tricks for (a) rearing and selection of thrips at different developmental stages, (b) treatment of the whole plant or an individual leaf with thrips, and (c) determination of feeding damage and visualization of thrips oviposition success in leaves.
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http://dx.doi.org/10.1007/978-1-0716-0142-6_7DOI Listing
December 2020

Bringing together Europe's young plant scientists.

New Phytol 2019 04;222(1):29-32

Plant Ecophysiology, Utrecht University, Padualaan 8, 3584CH Utrecht, the Netherlands.

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http://dx.doi.org/10.1111/nph.15691DOI Listing
April 2019

Thrips advisor: exploiting thrips-induced defences to combat pests on crops.

J Exp Bot 2018 04;69(8):1837-1848

Plant-Microbe Interactions, Department of Biology, Faculty of Science, Utrecht University, , TB Utrecht, The Netherlands.

Plants have developed diverse defence mechanisms to ward off herbivorous pests. However, agriculture still faces estimated crop yield losses ranging from 25% to 40% annually. These losses arise not only because of direct feeding damage, but also because many pests serve as vectors of plant viruses. Herbivorous thrips (Thysanoptera) are important pests of vegetable and ornamental crops worldwide, and encompass virtually all general problems of pests: they are highly polyphagous, hard to control because of their complex lifestyle, and they are vectors of destructive viruses. Currently, control management of thrips mainly relies on the use of chemical pesticides. However, thrips rapidly develop resistance to these pesticides. With the rising demand for more sustainable, safer, and healthier food production systems, we urgently need to pinpoint the gaps in knowledge of plant defences against thrips to enable the future development of novel control methods. In this review, we summarize the current, rather scarce, knowledge of thrips-induced plant responses and the role of phytohormonal signalling and chemical defences in these responses. We describe concrete opportunities for breeding resistance against pests such as thrips as a prototype approach for next-generation resistance breeding.
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http://dx.doi.org/10.1093/jxb/ery060DOI Listing
April 2018

Architecture and Dynamics of the Jasmonic Acid Gene Regulatory Network.

Plant Cell 2017 Sep 21;29(9):2086-2105. Epub 2017 Aug 21.

Plant-Microbe Interactions, Department of Biology, Utrecht University, 3508 TB, Utrecht, The Netherlands

Jasmonic acid (JA) is a critical hormonal regulator of plant growth and defense. To advance our understanding of the architecture and dynamic regulation of the JA gene regulatory network, we performed a high-resolution RNA-seq time series of methyl JA-treated at 15 time points over a 16-h period. Computational analysis showed that methyl JA (MeJA) induces a burst of transcriptional activity, generating diverse expression patterns over time that partition into distinct sectors of the JA response targeting specific biological processes. The presence of transcription factor (TF) DNA binding motifs correlated with specific TF activity during temporal MeJA-induced transcriptional reprogramming. Insight into the underlying dynamic transcriptional regulation mechanisms was captured in a chronological model of the JA gene regulatory network. Several TFs, including MYB59 and bHLH27, were uncovered as early network components with a role in pathogen and insect resistance. Analysis of subnetworks surrounding the TFs ORA47, RAP2.6L, MYB59, and ANAC055, using transcriptome profiling of overexpressors and mutants, provided insights into their regulatory role in defined modules of the JA network. Collectively, our work illuminates the complexity of the JA gene regulatory network, pinpoints and validates previously unknown regulators, and provides a valuable resource for functional studies on JA signaling components in plant defense and development.
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http://dx.doi.org/10.1105/tpc.16.00958DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5635973PMC
September 2017

VIH2 Regulates the Synthesis of Inositol Pyrophosphate InsP8 and Jasmonate-Dependent Defenses in Arabidopsis.

Plant Cell 2015 Apr 21;27(4):1082-97. Epub 2015 Apr 21.

Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany

Diphosphorylated inositol polyphosphates, also referred to as inositol pyrophosphates, are important signaling molecules that regulate critical cellular activities in many eukaryotic organisms, such as membrane trafficking, telomere maintenance, ribosome biogenesis, and apoptosis. In mammals and fungi, two distinct classes of inositol phosphate kinases mediate biosynthesis of inositol pyrophosphates: Kcs1/IP6K- and Vip1/PPIP5K-like proteins. Here, we report that PPIP5K homologs are widely distributed in plants and that Arabidopsis thaliana VIH1 and VIH2 are functional PPIP5K enzymes. We show a specific induction of inositol pyrophosphate InsP8 by jasmonate and demonstrate that steady state and jasmonate-induced pools of InsP8 in Arabidopsis seedlings depend on VIH2. We identify a role of VIH2 in regulating jasmonate perception and plant defenses against herbivorous insects and necrotrophic fungi. In silico docking experiments and radioligand binding-based reconstitution assays show high-affinity binding of inositol pyrophosphates to the F-box protein COI1-JAZ jasmonate coreceptor complex and suggest that coincidence detection of jasmonate and InsP8 by COI1-JAZ is a critical component in jasmonate-regulated defenses.
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http://dx.doi.org/10.1105/tpc.114.135160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4558690PMC
April 2015