Project description:Saliva was collected from c.40,000 diet reared aphids, pooled and concentrated. Samples were coming from 2 aphid species: Metopolophium dirhodum and Sitobion avenae. Proteins were fractionated using SDS PAGE and visible bands were subjected to in gel digestion. Tryptic peptides were analysised on a Thermo LTQ-FT. Protein identification from the MS/MS data was performed using the TurboSEQUEST algorithm in BioWorks v. 3.2 (Thermo Fisher Scientific) to correlate the data against ACYPIproteins v2.1, the official protein set of the pea aphid genome assembly (33291 predicted protein models; accessed November 2011) available at http://www.aphidbase.com/aphidbase/downloads. The following search parameters were used: precursor-ion mass tolerance of 1.5 Da, fragment ion tolerance of 1.0 Da with methionine oxidation and cysteine carboxyamidomethylation specified as differential modifications and a maximum of two missed cleavage sites allowed. Two filters were applied: XCorr vs. charge state (1, 2, 3 and 4 = 1.50, 2.00, 2.50 and 3.00 respectively) and peptide probability (p<0.001). Matches with multiple unique peptides and a cumulative XCorr >20 are reported. PLoS One accepted: Proteomic profiling of cereal aphid saliva reveals ubiquitous and adaptative secreted proteins. Rao S.A.K., Carolan, J.C. and Wilkinson, T.L.W.
Project description:In the field, plants usually have to face combined effects of abiotic and biotic stresses. In our study, two spring wheat cultivars Septima and Quintus were subjected to three water regimes (70, 50, 40 % soil water capacity SWC), aphid (Metopolophium dirhodum) infestation or the combination of both stresses, i.e., drought (50, 40% SWC) and aphids. The study has a 2x3x2 factorial design with three biological replicates. Our previous study (Saska et al. 2022) investigated plant morphophysiological characteristics and aphid life table. In the present study, the results of proteomic analysis using 2D-DIGE followed by MALDI-TOF/TOF protein identification are presented. Drought, but also aphid infestation led to alterations in 113 protein spots including proteins assigned to a variety of biological processes ranging from signalling via energy metabolism, redox regulation, stress and defense responses to secondary metabolism indicating a long-term adaptation to adverse conditions. The absence of specific proteins involved in plant response to herbivorous insects indicates a loss of resistance to aphids in modern wheat cultivars during the breeding process. Septima revealed enhanced tolerance with respect to Quintus as indicated by higher values of morphophysiological characteristics (above-ground biomass, leaf length, osmotic potential per full water saturation) and rel. abundance of proteins involved in mitochondrial respiration and ATP biosynthesis.
