Electrophoretic and immunological analyses of almond (Prunus dulcis L.) genotypes and hybrids

Aqueous extracts from sixty almond samples representing various genotypes a nd interspecies hybrids of almond, including almond-peach, were analyzed fo r protein and peptide content using electrophoresis, Western immunoblotting , and enzyme-linked immunosorbent assay (ELISA). Nondenaturing nondissociat ing polyacrylamide gel electrophoresis (NDND-PAGE) of the aqueous extracts indicated that a single major storage protein (almond major protein - AMP o r amandin) dominated the total soluble protein composition. Denaturing SDS- PAGE analyses of the aqueous extracts revealed that the AMP was mainly comp osed of two sets of polypeptides with estimated molecular masses in the ran ges of 38-41 kDa and 20-22 kDa, regardless of the source; however, distinct variations in the intensity and electrophoretic mobility of some bands wer e noted between samples. In addition to AMP, several minor polypeptides wer e also present in all the genotypes, and variations were seen in these as w ell. Regardless of the genotype, AMP was recognized in Western blots by rab bit polyclonal anti-AMP antibodies, mouse monoclonal anti-AMP antibodies (m Abs), and serum IgE from patients displaying strong serum anti-almond IgE r eactivity. As with protein staining results, antibody reactivity also revea led common patterns but displayed some variation between samples. An anti-A MP inhibition ELISA was used to quantify and compare aqueous extracts for v arious samples. All samples (n = 60) reacted in this assay with a mean +/- standard deviation tan) = 0.82 +/- 0.18 when compared to reference aqueous extract from Nonpareil designated as 1.0.