Molecular Interactions between the Specialist Herbivore Manduca sexta (Lepidoptera, Sphingidae) and Its Natural Host Nicotiana attenuata. VII. Changes in the Plant's Proteome

Abstract

-411 008 (M.S.), India (A.P.G.)When Manduca sexta attacks Nicotiana attenuata, fatty acid-amino acid conjugates (FACs) in the larvae's oral secretions (OS) are introduced into feeding wounds. These FACs trigger a transcriptional response that is similar to the response induced by insect damage. Using two-dimensional gel electrophoresis, matrix-assisted laser desorption ionization-time of flight, and liquid chromatography-tandem mass spectrometry, we characterized the proteins in phenolic extracts and in a nuclear fraction of leaves elicited by larval attack, and/or in leaves wounded and treated with OS, FAC-free OS, and synthetic FACs. Phenolic extracts yielded approximately 600 protein spots, many of which were altered by elicitation, whereas nuclear protein fractions yielded approximately 100 spots, most of which were unchanged by elicitation. Reproducible elicitor-induced changes in 90 spots were characterized. In general, proteins that increased were involved in primary metabolism, defense, and transcriptional and translational regulation; those that decreased were involved in photosynthesis. Like the transcriptional defense responses, proteomic changes were strongly elicited by the FACs in OS. A semiquantitative reverse transcription-PCR approach based on peptide sequences was used to compare transcript and protein accumulation patterns for 17 candidate proteins. In six cases the patterns of elicited transcript accumulation were consistent with those of elicited protein accumulation. Functional analysis of one of the identified proteins involved in photosynthesis, RuBPCase activase, was accomplished by virus-induced gene silencing. Plants with decreased levels of RuBPCase activase protein had reduced photosynthetic rates and RuBPCase activity, and less biomass, responses consistent with those of herbivore-attacked plants. We conclude that the response of the plant's proteome to herbivore elicitation is complex, and integrated transcriptome-proteome-metabolome analysis is required to fully understand this ubiquitous ecological interaction.The majority of studies examining the induced defense responses of plants after insect attack have focused on the dynamics of the specific genes, proteins, and metabolites that are thought to be responsible for changes in resistance elicited by attack. More recently, large-scale transcriptional analyses with microarrays have broadened the scope of the analysis and revealed coordinated changes in hundreds of transcripts, suggesting that large-scale shifts in metabolism accompany the activation of defense responses

Alteration of plant primary metabolism in response to insect herbivory

“…In most cases, the latter hypothesis, reduced photosynthesis in response to herbivory, is supported by actual measurements of changes in photosynthesis rate, photosynthesis-related gene expression, or production of proteins that are part of the photosynthetic apparatus (Reymond et al, 2004;Giri et al, 2006;Wei et al, 2009;Bilgin et al, 2010;Coppola et al, 2013;Appel et al, 2014). Reduced photosynthetic capacity can exceed what would be expected from the observed amount of foliar tissue that is removed (Zangerl et al, 2002).…”

Induced defence in lima bean plants exposed to the volatiles from two-spotted spider mite-infested conspecifics is independent of the major protein expression

“…In an interaction between wild tobacco plants (Nicotiana attenuata) and the tobacco hornworms (Manduca sexta), it is reported that ca. 15% of the proteins changed in the herbivory mimicking leaves with artificial damage and oral secretion of the tobacco hornworms (Giri et al 2006).…”

“…Giri et al (2006) reported that the amount of proteins involved in photosynthesis decreased in N. attenuata leaves when they were wounded and treated with oral secretions of M. sexta, which probably resulted in a reduced rate of photosynthesis. Such negative impacts from herbivory on photosynthetic activity have been reported (Zangerl et al 2002).…”

“…To understand the defensive response of volatileexposed plants in plantÁplant signaling, a comprehensive analysis that integrates transcriptome, proteome, and metabolome is essential (Giri et al 2006). For proteomic analysis, a targeted and more sensitive strategy through fractionation and concentration of proteins with post-translational modifications and/ or through isolation of proteins in a distinct localization in a cell is required.…”

An integrative statistical method to explore herbivory-specific responses in plants

“…Nicotiana attenuata is an annual fire-chasing plant native to the Great Basin Desert of the southwestern United States of America which has evolved a large number of specific induced responses against generalist and specialist herbivores. 14,15 Some of the essential nodes in the plant's transcriptome and metabolome responses to attack from larvae of the specialist lepidopteran herbivore, Manduca sexta, have been functionally characterized. 16 Feeding by this specialist herbivore or its simulation by the application of its oral secretions (OS) into puncture wounds produced by mechanical wounding activate rapid changes in the plant's metabolic and growth processes in order to facilitate de novo production of defense compounds.…”