Comparative Proteomics of Phytase-transgenic Maize Seeds Indicates Environmental Influence is More Important than that of Gene Insertion

Abstract

Proteomic differences were compared between phytase-transgenic (PT) maize seeds and nontransgenic (NT) maize seeds through two-dimensional electrophoresis (2-DE) with mass spectrometry (MS). When maize was grown under field conditions, 30 differentially accumulated proteins (DAPs) were successfully identified in PT seeds (PT/NT). Clusters of Orthologous Groups (COG) functional classification of these proteins showed that the largest group was associated with posttranslational modifications. To investigate the effects of environmental factors, we further compared the seed protein profiles of the same maize planted in a greenhouse or under field conditions. There were 76 DAPs between the greenhouse- and field-grown NT maize seeds and 77 DAPs between the greenhouse- and field-grown PT maize seeds However, under the same planting conditions, there were only 43 DAPs (planted in the greenhouse) or 37 DAPs (planted in the field) between PT and NT maize seeds. The results revealed that DAPs caused by environmental factors were more common than those caused by the insertion of exogenous genes, indicating that the environment has much more important effects on the seed protein profiles. Our maize seed proteomics results also indicated that the occurrence of unintended effects is not specific to genetically modified crops (GMCs); instead, such effects often occur in traditionally bred plants. Our data may be beneficial for biosafety assessments of GMCs at the protein profile level in the future.

Proteomic analysis of the seeds of transgenic rice lines and the corresponding nongenetically modified isogenic variety

“…These results are consistent with previously reported results for some other GM plants, such as transgenic maize, soybean and Arabidopsis 6, 30–33 . However, DAPs are not exclusively detected in GM crops but rather have also been observed during conventional plant breeding, 30, 34 hybridization 5, 24, 35 and even in different growth environments 36 …”

Plant breeding involving genetic engineering does not result in unacceptable unintended effects in rice relative to conventional cross‐breeding

“…We believe that rice is a good model plant for those investigations, as it is an important food crop and has been widely used in the past for plant biology studies, including omics analyses. Previous studies have suggested that environmental stresses brought more biological variation than transgenesis and genetic background in plants (Ouakfaoui and Miki, 2005;Batista et al, 2008;Montero et al, 2011;Asiago et al, 2012;Batista et al, 2017;Wang et al, 2018b;Tan et al, 2019). In the present study, the seeds of all 13 rice lines were prepared in the same way and were cultivated and managed under the same conditions in a greenhouse to minimize the effects of varying environmental conditions.…”

“…The advancements in omics‐based systems biology including genomics, transcriptomics, proteomics and metabolomics profiling have greatly enhanced the possibilities to analyze unintended changes in plants and these techniques have been shown to be powerful approaches for identifying changes in GE plants, as has been demonstrated for example for Arabidopsis, rice, maize, soybean, barley and pigeon pea (Kuiper et al ., 2001; Ouakfaoui and Miki, 2005; Ricroch et al ., 2011; Gong and Wang, 2013; Herman and Price, 2013; Wang et al ., 2018b; Tan et al ., 2019). However, in most study cases comparative analyses were restricted to one GE line and its closest non‐GE counterpart.…”

Comparative proteome analyses of rhizomania resistant transgenic sugar beets based on RNA silencing mechanism

“…41 A review of publications comparing the proteomes of transgenic versus non-transgenic plants showed a range of results. In many studies, the differences were minor, [42][43][44][45][46][47][48][49][50] while in some others the changes were substantial. [51][52][53] However, in most of these researches, no toxic or allergenic proteins were identified.…”

“…56 Furthermore, numerous studies have shown that the effects caused by environmental factors or conditions on protein profile are greater than or similar to the effects of single gene insertion. [45][46][47]49,52,53 To know whether the observed changes in protein expression in transgenic sugar beet events compared to the wild type are less than alterations due to environmental factors such as biotic and abiotic stresses, studies on protein profiles of sugar beet under stress conditions was reviewed. For instance, protein extracts of sugar beet genotypes resistant and susceptible to Fusarium oxysporum were compared with control samples in two and five days postinoculation by Larson and her colleagues.…”