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› 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

MATER

IALS

AN

D M

ETH

OD

S 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 IHarvested at the green pea stage (estimated maturity as no tenderometer available)

Experiment IIHarvest green pea stage using same days after flowering for all accessions (in progress)

MATER

IALS

AN

D M

ETH

OD

S II

Green pods were harvested and stored at -20 C until prepared for gas chromotography analysis

TechnicianSam Fuchs

SA

MPLIN

G T

HE A

CC

ES

SIO

NS

Pea seed removed from pod

Uniform seed selectedNote: Ekvall et al 2003

Three subsamples of 1 gram each of uniform color and size pea

Samples ground with a Terex Grinder

ETH

AN

OL E

XTR

AC

TIO

N

Samples dried down

CA

RB

OH

YD

RATES

D

ER

IVATIZ

ED

Seed extracts were taken to dryness under reducedpressure.

Derivatized with a mixture of trimethylsilyl imidazole:pyridine(1:1, v/v).

GA

S C

HR

OM

OTO

GR

APH

Y

Soluble carbohydrates were converted into trimethylsilylderivatives 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).

Results from Experiment I

#574510-USA

#411143-New Zealand

#356974-India

#413684-Hungary

#164971-Turkey

#244150-Netherla

nds0.1

1

10

100

1000

10000

Fructose Glucose Sorbitol B-pheyl-Gluco. Sucrose Raffinose Stachyose Verbascose

USDA World Pea Gerplasm Analysis of Carbohydrates

Car

bo

hyd

rate

, u

g/g

(F

W),

Lo

g10

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….

Post-harvest chemist:Professor John Fellman