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Lin PA, Kansman J, Chuang WP, Robert C, Erb M, Felton GW. Water availability and plant-herbivore interactions. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:2811-2828. [PMID: 36477789 DOI: 10.1093/jxb/erac481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 12/04/2022] [Indexed: 06/06/2023]
Abstract
Water is essential to plant growth and drives plant evolution and interactions with other organisms such as herbivores. However, water availability fluctuates, and these fluctuations are intensified by climate change. How plant water availability influences plant-herbivore interactions in the future is an important question in basic and applied ecology. Here we summarize and synthesize the recent discoveries on the impact of water availability on plant antiherbivore defense ecology and the underlying physiological processes. Water deficit tends to enhance plant resistance and escape traits (i.e. early phenology) against herbivory but negatively affects other defense strategies, including indirect defense and tolerance. However, exceptions are sometimes observed in specific plant-herbivore species pairs. We discuss the effect of water availability on species interactions associated with plants and herbivores from individual to community levels and how these interactions drive plant evolution. Although water stress and many other abiotic stresses are predicted to increase in intensity and frequency due to climate change, we identify a significant lack of study on the interactive impact of additional abiotic stressors on water-plant-herbivore interactions. This review summarizes critical knowledge gaps and informs possible future research directions in water-plant-herbivore interactions.
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Affiliation(s)
- Po-An Lin
- Department of Entomology, National Taiwan University, Taipei, Taiwan
| | - Jessica Kansman
- Department of Entomology, the Pennsylvania State University, University Park, PA, USA
| | - Wen-Po Chuang
- Department of Agronomy, National Taiwan University, Taipei, Taiwan
| | | | - Matthias Erb
- Institute of Plant Science, University of Bern, Bern, Switzerland
| | - Gary W Felton
- Department of Entomology, the Pennsylvania State University, University Park, PA, USA
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Suresh BV, Choudhary P, Aggarwal PR, Rana S, Singh RK, Ravikesavan R, Prasad M, Muthamilarasan M. De novo transcriptome analysis identifies key genes involved in dehydration stress response in kodo millet (Paspalum scrobiculatum L.). Genomics 2022; 114:110347. [PMID: 35337948 DOI: 10.1016/j.ygeno.2022.110347] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 02/08/2022] [Accepted: 03/18/2022] [Indexed: 01/14/2023]
Abstract
Kodo millet (Paspalum scrobiculatum L.) is a small millet species known for its excellent nutritional and climate-resilient traits. To understand the genes and pathways underlying dehydration stress tolerance of kodo millet, the transcriptome of cultivar 'CO3' subjected to dehydration stress (0 h, 3 h, and 6 h) was sequenced. The study generated 239.1 million clean reads that identified 9201, 9814, and 2346 differentially expressed genes (DEGs) in 0 h vs. 3 h, 0 h vs. 6 h, and 3 h vs. 6 h libraries, respectively. The DEGs were found to be associated with vital molecular pathways, including hormone metabolism and signaling, antioxidant scavenging, photosynthesis, and cellular metabolism, and were validated using qRT-PCR. Also, a higher abundance of uncharacterized genes expressed during stress warrants further studies to characterize this class of genes to understand their role in dehydration stress response. Altogether, the study provides insights into the transcriptomic response of kodo millet during dehydration stress.
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Affiliation(s)
- Bonthala Venkata Suresh
- Quantitative Genetics and Genomics of Plants, Heinrich Heine University, Düsseldorf 40225, Germany.
| | - Pooja Choudhary
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - Pooja Rani Aggarwal
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - Sumi Rana
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
| | | | - Rajasekaran Ravikesavan
- Department of Millets, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
| | - Manoj Prasad
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India; National Institute of Plant Genome Research, New Delhi 110067, India.
| | - Mehanathan Muthamilarasan
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
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Garcia A, Martinez M, Diaz I, Santamaria ME. The Price of the Induced Defense Against Pests: A Meta-Analysis. FRONTIERS IN PLANT SCIENCE 2021; 11:615122. [PMID: 33552106 PMCID: PMC7859116 DOI: 10.3389/fpls.2020.615122] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/23/2020] [Indexed: 05/21/2023]
Abstract
Plants and phytophagous arthropods have co-evolved for millions of years. During this long coexistence, plants have developed defense mechanisms including constitutive and inducible defenses. In an effort to survive upon herbivore attack, plants suffer a resource reallocation to facilitate the prioritization of defense toward growth. These rearrangements usually end up with a penalty in plant growth, development or reproduction directly linked to crop losses. Achieving the balance to maximize crop yield requires a fine tune regulation specific for each host-arthropod combination, which remains to be fully elucidated. The purpose of this work is to evaluate the effects of induced plant defenses produced upon pest feeding on plant fitness and surrogate parameters. The majority of the studies are focused on specific plant-pest interactions based on artificial herbivory damage or simulated defoliation on specific plant hosts. In this meta-analysis, the relevance of the variables mediating plant-pest interactions has been studied. The importance of plant and pest species, the infestation conditions (plant age, length/magnitude of infestation) and the parameters measured to estimate fitness (carbohydrate content, growth, photosynthesis and reproduction) in the final cost have been analyzed through a meta-analysis of 209 effects sizes from 46 different studies. Herbivore infestation reduced growth, photosynthesis and reproduction but not carbohydrate content. When focusing on the analyses of the variables modulating plant-pest interactions, new conclusions arise. Differences on the effect on plant growth and photosynthesis were observed among different feeding guilds or plant hosts, suggesting that these variables are key players in the final effects. Regarding the ontogenetic stage of a plant, negative effects were reported only in infestations during the vegetative stage of the plant, while no effect was observed during the reproductive stage. In addition, a direct relation was found between the durability and magnitude of the infestation, and the final negative effect on plant fitness. Among the parameters used to estimate the cost, growth and photosynthesis revealed more differences among subgroups than reproduction parameters. Altogether, this information on defense-growth trade-offs should be of great help for the scientific community to design pest management strategies reducing costs.
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Affiliation(s)
- Alejandro Garcia
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y Alimentación, Madrid, Spain
| | - Manuel Martinez
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y Alimentación, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Isabel Diaz
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y Alimentación, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - M. Estrella Santamaria
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y Alimentación, Madrid, Spain
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Gomez-Sanchez A, Gonzalez-Melendi P, Santamaria ME, Arbona V, Lopez-Gonzalvez A, Garcia A, Hensel G, Kumlehn J, Martinez M, Diaz I. Repression of drought-induced cysteine-protease genes alters barley leaf structure and responses to abiotic and biotic stresses. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2143-2155. [PMID: 30452688 DOI: 10.1093/jxb/ery410] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 11/08/2018] [Indexed: 05/23/2023]
Abstract
To survive under water deficiency, plants alter gene expression patterns, make structural and physiological adjustments, and optimize the use of water. Rapid degradation and turnover of proteins is required for effective nutrient recycling. Here, we examined the transcriptional responses of the C1A cysteine protease family to drought in barley and found that four genes were up-regulated in stressed plants. Knock-down lines for the protease-encoding genes HvPap-1 and HvPap-19 showed unexpected changes in leaf cuticle thickness and stomatal pore area. The efficiency of photosystem II and the total amount of proteins were almost unaltered in stressed transgenic plants while both parameters decreased in stressed wild-type plants. Although the patterns of proteolytic activities in the knock-down lines did not change, the amino acid accumulation increased in response to drought, concomitant with a higher ABA content. Whilst jasmonic acid (JA) and JA-Ile concentrations increased in stressed leaves of the wild-type and the HvPap-1 knock-down lines, their levels were lower in the HvPap-19 knock-down lines, suggesting the involvement of a specific hormone interaction in the process. Our data indicate that the changes in leaf cuticle thickness and stomatal pore area had advantageous effects on leaf defense against fungal infection and mite feeding mediated by Magnaporthe oryzae and Tetranychus urticae, respectively.
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Affiliation(s)
- Andrea Gomez-Sanchez
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA). Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA). Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
| | - Pablo Gonzalez-Melendi
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA). Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA). Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología y Biología Vegetal - Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Avda. Complutense, Madrid, Spain
| | - M Estrella Santamaria
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA). Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA). Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología y Biología Vegetal - Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Avda. Complutense, Madrid, Spain
| | - Vicente Arbona
- Ecofisiologia i Biotecnologia, Dpt. Ciències Agràries i del Medi Natural, Universitat Jaume I - Campus Riu Sec, Castelló de la Plana, Spain
| | - Angeles Lopez-Gonzalvez
- Centre for Metabolomics and Bioanalysis, Facultad de Farmacia, Universidad CEU San Pablo, Campus Monteprincipe, Boadilla del Monte, Madrid, Spain
| | - Antonia Garcia
- Centre for Metabolomics and Bioanalysis, Facultad de Farmacia, Universidad CEU San Pablo, Campus Monteprincipe, Boadilla del Monte, Madrid, Spain
| | - Goetz Hensel
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Gatersleben, Germany
| | - Jochen Kumlehn
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Gatersleben, Germany
| | - Manuel Martinez
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA). Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA). Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología y Biología Vegetal - Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Avda. Complutense, Madrid, Spain
| | - Isabel Diaz
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA). Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA). Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología y Biología Vegetal - Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Avda. Complutense, Madrid, Spain
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Santamaría ME, Martínez M, Arnaiz A, Rioja C, Burow M, Grbic V, Díaz I. An Arabidopsis TIR-Lectin Two-Domain Protein Confers Defense Properties against Tetranychus urticae. PLANT PHYSIOLOGY 2019; 179:1298-1314. [PMID: 30765478 PMCID: PMC6446783 DOI: 10.1104/pp.18.00951] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 02/04/2019] [Indexed: 05/13/2023]
Abstract
Plant immunity depends on fast and specific transcriptional reprogramming triggered by the perception of biotic stresses. Numerous studies have been conducted to better understand the response of plants to the generalist herbivore two-spotted spider mite (Tetranychus urticae). However, how plants perceive mites and how this perception is translated into changes in gene expression are largely unknown. In this work, we identified a gene induced in Arabidopsis (Arabidopsis thaliana) upon spider mite attack that encodes a two-domain protein containing predicted lectin and Toll/Interleukin-1 receptor domains. The gene, previously named PP2-A5, belongs to the Phloem Protein2 family. Biotic assays showed that PP2-A5 confers tolerance to T. urticae Overexpression or knockout of PP2-A5 leads to transcriptional reprogramming that alters the balance of hormone accumulation and corresponding signaling pathways. The nucleocytoplasmic location of this protein supports a direct interaction with regulators of gene transcription, suggesting that the combination of two putative signaling domains in a single protein may provide a novel mechanism for regulating gene expression. Together, our results suggest that PP2-A5 improves the ability to defend against T. urticae by participating in the tight regulation of hormonal cross talk upon mite feeding. Further research is needed to determine the mechanism by which this two-domain protein functions and to clarify its molecular role in signaling following a spider mite attack.
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Affiliation(s)
- M Estrella Santamaría
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223 Madrid, Spain
- Departamento de Biotecnología y Biología Vegetal-Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, 28040 Madrid, Spain
| | - Manuel Martínez
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223 Madrid, Spain
- Departamento de Biotecnología y Biología Vegetal-Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, 28040 Madrid, Spain
| | - Ana Arnaiz
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223 Madrid, Spain
| | - Cristina Rioja
- DynaMo Center, Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Meike Burow
- DynaMo Center, Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Vojislava Grbic
- Department of Biology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Isabel Díaz
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223 Madrid, Spain
- Departamento de Biotecnología y Biología Vegetal-Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, 28040 Madrid, Spain
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de Lillo E, Pozzebon A, Valenzano D, Duso C. An Intimate Relationship Between Eriophyoid Mites and Their Host Plants - A Review. FRONTIERS IN PLANT SCIENCE 2018; 9:1786. [PMID: 30564261 PMCID: PMC6288765 DOI: 10.3389/fpls.2018.01786] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 11/16/2018] [Indexed: 05/20/2023]
Abstract
Eriophyoid mites (Acari Eriophyoidea) are phytophagous arthropods forming intimate relationships with their host plants. These mites are associated with annual and perennial plants including ferns, and are highly specialized with a dominant monophagy. They can be classified in different ecological classes, i.e., vagrant, gall-making and refuge-seeking species. Many of them are major pests and some of them are vectors of plant pathogens. This paper critically reviews the knowledge on eriophyoids of agricultural importance with emphasis on sources for host plant resistance to these mites. The role of species belonging to the family Eriophyidae as vectors of plant viruses is discussed. Eriophyoid-host plant interactions, the susceptibility within selected crops and main host plant tolerance/resistance mechanisms are discussed. Fundamental concepts, subjects, and problems emerged in this review are pointed out and studies are suggested to clarify some controversial points.
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Affiliation(s)
- Enrico de Lillo
- Department of Soil, Plant and Food Sciences, Entomological and Zoological Section, University of Bari Aldo Moro, Bari, Italy
| | - Alberto Pozzebon
- Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Padova, Italy
| | - Domenico Valenzano
- Department of Soil, Plant and Food Sciences, Entomological and Zoological Section, University of Bari Aldo Moro, Bari, Italy
| | - Carlo Duso
- Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Padova, Italy
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Schimmel BCJ, Alba JM, Wybouw N, Glas JJ, Meijer TT, Schuurink RC, Kant MR. Distinct Signatures of Host Defense Suppression by Plant-Feeding Mites. Int J Mol Sci 2018; 19:E3265. [PMID: 30347842 PMCID: PMC6214137 DOI: 10.3390/ijms19103265] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/12/2018] [Accepted: 10/14/2018] [Indexed: 01/09/2023] Open
Abstract
Tomato plants are attacked by diverse herbivorous arthropods, including by cell-content-feeding mites, such as the extreme generalist Tetranychus urticae and specialists like Tetranychus evansi and Aculops lycopersici. Mite feeding induces plant defense responses that reduce mite performance. However, T. evansi and A. lycopersici suppress plant defenses via poorly understood mechanisms and, consequently, maintain a high performance on tomato. On a shared host, T. urticae can be facilitated by either of the specialist mites, likely due to the suppression of plant defenses. To better understand defense suppression and indirect plant-mediated interactions between herbivorous mites, we used gene-expression microarrays to analyze the transcriptomic changes in tomato after attack by either a single mite species (T. urticae, T. evansi, A. lycopersici) or two species simultaneously (T. urticae plus T. evansi or T. urticae plus A. lycopersici). Additionally, we assessed mite-induced changes in defense-associated phytohormones using LC-MS/MS. Compared to non-infested controls, jasmonates (JAs) and salicylate (SA) accumulated to higher amounts upon all mite-infestation treatments, but the response was attenuated after single infestations with defense-suppressors. Strikingly, whereas 8 to 10% of tomato genes were differentially expressed upon single infestations with T. urticae or A. lycopersici, respectively, only 0.1% was altered in T. evansi-infested plants. Transcriptome analysis of dual-infested leaves revealed that A. lycopersici primarily suppressed T. urticae-induced JA defenses, while T. evansi dampened T. urticae-triggered host responses on a transcriptome-wide scale. The latter suggests that T. evansi not solely down-regulates plant gene expression, but rather directs it back towards housekeeping levels. Our results provide valuable new insights into the mechanisms underlying host defense suppression and the plant-mediated facilitation of competing herbivores.
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Affiliation(s)
- Bernardus C J Schimmel
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
| | - Juan M Alba
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
| | - Nicky Wybouw
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium.
| | - Joris J Glas
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
| | - Tomas T Meijer
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
| | - Robert C Schuurink
- Department of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, P.O. Box 94215, 1090 GE Amsterdam, The Netherlands.
| | - Merijn R Kant
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
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Bui H, Greenhalgh R, Ruckert A, Gill GS, Lee S, Ramirez RA, Clark RM. Generalist and Specialist Mite Herbivores Induce Similar Defense Responses in Maize and Barley but Differ in Susceptibility to Benzoxazinoids. FRONTIERS IN PLANT SCIENCE 2018; 9:1222. [PMID: 30186298 PMCID: PMC6110934 DOI: 10.3389/fpls.2018.01222] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 07/31/2018] [Indexed: 05/20/2023]
Abstract
While substantial progress has been made in understanding defense responses of cereals to insect herbivores, comparatively little is known about responses to feeding by spider mites. Nevertheless, several spider mite species, including the generalist Tetranychus urticae and the grass specialist Oligonychus pratensis, cause damage on cereals such as maize and wheat, especially during drought stress. To understand defense responses of cereals to spider mites, we characterized the transcriptomic responses of maize and barley to herbivory by both mite species, and included a wounding control against which modulation of defenses could be tested. T. urticae and O. pratensis induced highly correlated changes in gene expression on both maize and barley. Within 2 h, hundreds of genes were upregulated, and thousands of genes were up- or downregulated after 24 h. In general, expression changes were similar to those induced by wounding, including for genes associated with jasmonic acid biosynthesis and signaling. Many genes encoding proteins involved in direct defenses, or those required for herbivore-induced plant volatiles, were strongly upregulated in response to mite herbivory. Further, biosynthesis genes for benzoxazinoids, which are specialized compounds of Poaceae with known roles in deterring insect herbivores, were induced in maize. Compared to chewing insects, spider mites are cell content feeders and cause grossly different patterns of tissue damage. Nonetheless, the gene expression responses of maize to both mite herbivores, including for phytohormone signaling pathways and for the synthesis of the benzoxazinoid 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside, a known defensive metabolite against caterpillars, resembled those reported for a generalist chewing insect, Spodoptera exigua. On maize plants harboring mutations in several benzoxazinoid biosynthesis genes, T. urticae performance dramatically increased compared to wild-type plants. In contrast, no difference in performance was observed between mutant and wild-type plants for the specialist O. pratensis. Collectively, our data provide little evidence that maize and barley defense responses differentiate herbivory between T. urticae and O. pratensis. Further, our work suggests that the likely route to specialization for O. pratensis involved the evolution of a robust mechanism to cope with the benzoxazinoid defenses of its cereal hosts.
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Affiliation(s)
- Huyen Bui
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States
| | - Robert Greenhalgh
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States
| | - Alice Ruckert
- Department of Biology, Utah State University, Logan, UT, United States
| | | | - Sarah Lee
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States
| | | | - Richard M. Clark
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, United States
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