Comparative proteomic analysis of genetically modified maize grown under different agroecosystems conditions in Brazil

Abstract

Background: Profiling technologies allow the simultaneous measurement and comparison of thousands of cell components without prior knowledge of their identity. In the present study, we used two-dimensional gel electrophoresis combined with mass spectrometry to evaluate protein expression of Brazilian genetically modified maize hybrid grown under different agroecosystems conditions. To this effect, leaf samples were subjected to comparative analysis using the near-isogenic non-GM hybrid as the comparator.

Results: In the first stage of the analysis, the main sources of variation in the dataset were identified by using Principal Components Analysis which correlated most of the variation to the different agroecosystems conditions. Comparative analysis within each field revealed a total of thirty two differentially expressed proteins between GM and non-GM samples that were identified and their molecular functions were mainly assigned to carbohydrate and energy metabolism, genetic information processing and stress response.

Conclusions: To the best of our knowledge this study represents the first evidence of protein identities with differentially expressed isoforms in Brazilian MON810 genetic background hybrid grown under field conditions. As global databases on outputs from "omics" analysis become available, these could provide a highly desirable benchmark for safety assessments.

Figure 1

PCA score plots of genetically modified and non-genetically modified near isogenic maize hybrids grown at Campos Novos (Brazil) (a) and Chapecó (b), Brazil.

Figure 2

PCA score plots of genetically modified (a) and non-genetically modified near isogenic maize hybrids (b) across location (grown at Campos Novos and Chapecó, Brazil).

Figure 3

PCA score plots of genetically modified and non-genetically modified near isogenic maize hybrids across both location (grown at Campos Novos and Chapecó, Brazil). All gels from the experiment dataset were analyzed together.

Figure 4

Representative two-dimensional gel electrophoresis (2-DE) maps of the proteome of genetically modified maize plants (MON810 event) and non-modified maize grown in Campos Novos (4a and 4b respectively) and Chapecó (4c and 4d respectively) between pH 4 and 7.Linear isoelectric focusing pH 4–7 for the first dimension and 12% SDS–PAGE gels in the second dimension were used. Molecular masses range from 10 to 250 kDa are given on the left side. The top-left corners of the yellow boxes point to differentially expressed protein spots selected for mass spectrometry identification. ID of identified proteins from Table 2 are indicated in yellow boxes.