Transcriptomic responses of Solanum dulcamara to natural and simulated herbivory

Abstract

Plants are attacked by diverse herbivores and respond with manifold defence responses. To study transcriptional and other early regulation events of these plant responses, herbivory is often simulated to standardize the temporal and spatial dynamics that vary tremendously for natural herbivory. Yet, to what extent such simulations of herbivory are able to elicit the same plant response as real herbivory remains largely undetermined. We examined the transcriptional response of a wild model plant to herbivory by lepidopteran larvae and to a commonly used herbivory simulation by applying the larvae's oral secretions to standardized wounds. We designed a microarray for Solanum dulcamara and showed that the transcriptional responses to real and to simulated herbivory by Spodoptera exigua overlapped moderately by about 40%. Interestingly, certain responses were mimicked better than others; 60% of the genes upregulated but not even a quarter of the genes downregulated by herbivory were similarly affected by application of oral secretions to wounds. While the regulation of genes involved in signalling, defence and water stress was mimicked well by the simulated herbivory, most of the genes related to photosynthesis, carbohydrate-and lipid metabolism were exclusively regulated by real herbivory. Thus, wounding and application of oral secretions decently mimics herbivory-induced defence responses but likely not the reallocation of primary metabolites induced by real herbivory.caterpillar oral secretions, elicitation, induced plant defence, microarray, photosynthesis, phytohormone signalling, plant-insect interactions, simulated herbivory

Insect egg deposition renders plant defence against hatching larvae more effective in a salicylic acid‐dependent manner

“…Larval feeding resulted in transcriptional changes of 1,129 genes in egg‐free leaves (Figure a and Appendix S1, T vs. C) and of 1,266 genes in previously egg‐carrying leaves (Figure a and Appendix S1, PT vs. C). The feeding‐induced genes map to “biological process” GO terms that reflect a characteristic transcriptional plant response to chewing herbivory, for example, “response to wounding,” “response to jasmonic acid,” or “secondary metabolite biosynthetic process” (Appel et al, ; Lortzing et al, ; Reymond et al, ), and also to GO terms that are associated with SA‐mediated plant defence responses like “response to salicylic acid” or “systemic acquired resistance” (Appendix S2, T vs. C and PT vs. C). Transcripts that were downregulated by feeding are especially overrepresented in GO terms associated with auxin‐mediated signalling (Appendix S2, T vs. C and PT vs. C).…”

Moth oviposition shapes the species-specific transcriptional and phytohormonal response of Nicotiana attenuata to larval feeding

“…However, S. exigua feeding altered more than 2000 genes more than M. sexta feeding. Although, this was more pronounced for down-regulated genes, defence-related genes and signalling pathways were often stronger induced in response to the generalist (Figs 2 – 7 ) and the majority of genes down-regulated after herbivory are usually related to primary plant metabolism 48 . N. attenuata effectively defends itself against S. exigua 11 , 46 , 49 , whereas M. sexta is relatively tolerant to many of its direct defences 47 , 50 .…”

Solanum dulcamara's response to eggs of an insect herbivore comprises ovicidal hydrogen peroxide production

“…) containing 32 157 contigs and that was validated and described in detail elsewhere (Lortzing et al . ). After the microarray was washed twice, the fluorescence signals were detected by the SureScan Microarray Scanner (Agilent Technologies) at a resolution of 3 μ m per pixel.…”

“…Fluorescent cRNA was generated by using the Low Input QuickAmp Labelling Kit (Agilent Technologies) using oligo-dT primer following the manufacture's protocol. Of the cyanine 3-CTP-labelled cRNA, 600 ng was hybridized by using the Agilent Gene Expression Hybridization Kit (Agilent Technologies) following the manufacturer's protocol at 65°C for 17 h on an 8 × 60 K Agilent custom microarray that was based on a S. dulcamara transcriptome assembly (D'Agostino et al 2013) containing 32 157 contigs and that was validated and described in detail elsewhere (Lortzing et al 2017). After the microarray was washed twice, the fluorescence signals were detected by the SureScan Microarray Scanner (Agilent Technologies) at a resolution of 3 μm per pixel.…”