Diversity in seed storage protein profile of oilseed crop Plukenetia volubilis from Peruvian Amazon

Abstract

Sacha inchi (Plukenetia volubilis L.) is a plant native to the Peruvian Amazon and produces seeds rich in some nutraceutical compounds with a high protein content. The present work aimed to characterize P. volubilis seed proteins and compare their proteomic profile between different P. volubilis populations. Crude protein content in the seeds was detected at a mean level of 22.56% with the major proportion of albumins and globulins (16.37%), followed by glutelins (5.87%) and a very low content of prolamins (0.33%). Sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) gel electrophoresis of both total seed flour and Osborne's protein fractions of different populations showed that proteins were concentrated in the 8-75 kDa range. Differences in abundance of proteins between Sacha inchi populations were detected by SDS-PAGE and two-dimensional (2-DE) gel electrophoresis. Gel protein bands and spots of interest were excised, digested with trypsin and analyzed by nano-liquid chromatography/tandem mass spectrometry (nLC-MS/MS). This is the first direct identification of these proteins in actual Sacha inchi seeds. Three proteins (Oleosin 2, Oleosin 3 and elongation factor 1-alpha) directly from P. volubilis and peptides with a sequence identical to 56 proteins from the Euphorbiaceae family were detected. This characterization of seed storage protein, their variability within populations and identification of important proteins provide a basis for further investigations for the food industry and bioengineering.