Abstract
BackgroundVarious factors shape the response of plants to herbivorous insects, including wounding patterns, specific chemical effectors and feeding habits of the attacking herbivore. Here we performed a comparative proteomic analysis of the plant's response to wounding and herbivory, using as a model potato plants (Solanum tuberosum L.) subjected to mechanical wounding, defoliation by the Colorado potato beetle Leptinotarsa decemlineata Say, or phloem sap feeding by the potato aphid Macrosiphum euphorbiae Thomas.ResultsOut of ~500 leaf proteins monitored by two-dimensional gel electrophoresis (2-DE), 31 were up- or downregulated by at least one stress treatment compared to healthy control plants. Of these proteins, 29 were regulated by beetle chewing, 8 by wounding and 8 by aphid feeding. Some proteins were up- or downregulated by two different treatments, while others showed diverging expression patterns in response to different treatments. A number of modulated proteins identified by mass spectrometry were typical defense proteins, including wound-inducible protease inhibitors and pathogenesis-related proteins. Proteins involved in photosynthesis were also modulated, notably by potato beetle feeding inducing a strong decrease of some photosystem I proteins. Quantitative RT PCR assays were performed with nucleotide primers for photosynthesis-related proteins to assess the impact of wounding and herbivory at the gene level. Whereas different, sometimes divergent, responses were observed at the proteome level in response to wounding and potato beetle feeding, downregulating effects were systematically observed for both treatments at the transcriptional level.ConclusionsThese observations illustrate the differential impacts of wounding and insect herbivory on defense- and photosynthesis-related components of the potato leaf proteome, likely associated with the perception of distinct physical and chemical cues in planta.
Highlights
Various factors shape the response of plants to herbivorous insects, including wounding patterns, specific chemical effectors and feeding habits of the attacking herbivore
Mithöfer et al [19] showed for instance that sustained mechanical wounding applied to lima bean leaves in such a way as to reproduce the leaf removal pattern observed with Spodoptora littoralis larvae is required to reproduce volatile emission patterns similar to those induced by the insect
MRNA transcripts for proteinase inhibitor II (Pin-II), a wound-inducible protein, were detected in leaf extracts of plants subjected to wounding or potato beetle chewing while remaining at lower levels in control and aphid-treated plants (Student's t-test; P = 0.0001)
Summary
Various factors shape the response of plants to herbivorous insects, including wounding patterns, specific chemical effectors and feeding habits of the attacking herbivore. Aphids establish a prolonged interaction with their host plant, from which they take large quantities of phloem sap [25]. Their specialized mouthparts, or stylets, allow them to reach sieve tubes via an intercellular route, without causing major damage to plant tissues [26,27]. This feeding behaviour minimizing tissue injury translates into a unique type of plant-insect interaction, where defense genes induced in planta are in part similar to those induced by pathogenic infection [28,29]
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