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Genetic diversity of Pisum sativum wrinkled seed collection for seed sugar composition and concentration . Clarice J. Coyne, Rebecca J. McGee, D. Scott Mattinson, Sam Fuchs, John Fellman. Objective. Genetic diversity of oligosaccharides in USDA pea germplasm
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Genetic diversity of Pisumsativum wrinkled seed collection for seed sugar composition and concentration Clarice J. Coyne, Rebecca J. McGee, D. Scott Mattinson, Sam Fuchs, John Fellman
Objective • Genetic diversity of oligosaccharides in USDA pea germplasm • Set I: wrinkled green pea germplasm • Harvested at green processing stage • Identify diversity for breeders • Soybean (Dierking & Bilyeu 2008)
Pea carbohydrates significance • Pea : inexpensive source of protein, carbohydrate, vitamins and minerals. • Probiotic: summary by Ekvall et al. 2006 Food Chemistry 94: 513–519. • Antinutritional factors • Frost tolerance • Desiccation protection • Carbohydrate transport in the phloem
Introduction to pea LMWC • Low molecular weight carbohydrates in pea seed include: • Sucrose • Fructose • Glucose • Sorbitol • Raffinose • Stachyose • Verbascose
Materials and Methods I Wrinkled pea from the USDA pea core collection and from the VIR collection Six plants per accession grown in potting mix under greenhouse conditions Experiment I Harvested at the green pea stage (estimated maturity as no tenderometer available) Experiment II Harvest green pea stage using same days after flowering for all accessions (in progress)
Materials and Methods II Green pods were harvested and stored at -20 C until prepared for gas chromotography analysis Technician Sam Fuchs
Sampling the accessions Pea seed removed from pod Uniform seed selected Note: Ekvall et al 2003 Three subsamples of 1 gram each of uniform color and size pea Samples ground with a Terex Grinder
Carbohydrates derivatized Seed extracts were taken to dryness under reduced pressure. Derivatized with a mixture of trimethylsilyl imidazole:pyridine (1:1, v/v).
Gas chromotography Soluble carbohydrates were converted into trimethylsilyl derivatives and separated by capillary gas chromatography as described previously (Peterbauer et al . 1998). For quantification, ratios of peak areas to that of the internal standard (phenyl b-D -glucopyranoside) were compared with those of external standards (Sigma).
Summary • Germplasm rich source of diversity in low molecular weight carbohydrates • Methods yield high quality data with on low standard errors • Experiment II: use DAP for uniform maturity (100 accessions) • Experiment III: dry pea accessions
Many thanks • USDA Pisum CGC Evaluation funding • Greenhouse helpers Landon Charlo, Alison Hitchcock, Nancy Nydegger-Paulitz • Collaborators Rebecca J. McGee, D. Scott Mattinson, Sam Fuchs, and….