Poster: Late and Moved Abstracts

Abs # 1413: Quantification of natural variability in the seed proteome of Arabidopsis thaliana ecotypes

Presenter:	Ruebelt, Martin C, Martin.C.Ruebelt@monsanto.com
Authors	Ruebelt, Martin C (B) (C)  Leimgruber, Nancy  (A)   Lipp, Markus.  (A)   Jany, Klaus-Dieter  (B)   Engle, Karl-Heinz  (C)   Reynolds, Tracey L (A)   George, Cherian  (A)   Astwood, James D (A)
Affiliations:	(A): Monsanto (B): Technical University of Munich, Germany; (C): Federal Research Center for Nutrition, Germany;

Current tools used to assess the safety of biotech crops emphasize the investigation of unintended effects caused by the expression of transgenes or by pleiotropy. These tools include multi-site and multi-year agronomic testing, composition (biochemical) analyses, nutritional and toxicological evaluations. To complement these tools, we are investigating proteomics. 2-D electrophoresis was optimized to obtain well-resolved and reproducible patterns of seed proteins from 12 Arabidopsis thaliana ecotypes with different geographic origins. The method covers proteins with isoelectric points between 4 and 9 and molecular weights in the range of 6 to 120 kDa. The proteome patterns were analyzed by computer assisted image analysis. Approximately 600 protein spots were detected for each ecotype. The protein profiles were compared and were catalogued on the basis of presence, absence and intensity (volume). The total number of resolved protein spots found among the 12 ecotypes was 931. Significant natural variability in protein expression was observed. 597 of the 931 detected protein spots vary in presence/absence among ecotypes. 117 ecotype specific spots were detected among the ecotypes. Spot quantity variation of more than 3-fold was found for 25 % of the 334 spots detected in all ecotypes. A positive correlation was observed between ecotype phenotype and proteome complexity (i.e. uniqueness). In testing for unintended effects, we suggest that experimental designs must account for natural variability, which in the case of the proteome, can be substantial. An evaluation of the impact of genotype and the subsequent heritability of seed protein profiles should be viewed as a pre-requisite baseline database establishing a context for comparative analyses.