Relative quantitation of ricin in Ricinus communis seeds by image processing

Quantitative and qualitative assays for specific seed proteins could be used as a screening tool in breeding for improved seed characteristics. These assays could be especially useful for selection of castor seeds for altered expression of the toxin ricin. The technique described here includes extraction of water soluble proteins from partial seed samples so that the remaining seed is viable and can be used for genetic evaluation. Individual proteins are resolved by SDS-PAGE and identified by MALDI-TOF/TOF mass spectrometry. Once toxin proteins are correlated with bands in stained SDS-PAGE gels, image processing is used to estimate the relative quantities of these proteins in extracts from individual seeds. The results indicate that this method can serve as a relatively inexpensive and reliable assay for ricin content in castor endosperm tissues and this approach could facilitate the selection of low ricin castor varieties.