Soybean sprouts have been used as a food in the Orient since ancient times.
In this study, 92 restriction fragment length polymorphism (RFLP) loci and
two morphological markers (WI and T) were used to identify quantitative tr
ait loci (QTLs) associated with soybean sprout-related traits in 100 F-2-de
rived lines from the cross of 'Pureunkong' x 'Jinpumkong 2'. The genetic ma
p consisted of 76 loci which covered about 756 cM and converged into 20 lin
kage groups. Eighteen markers remained unlinked. Phenotypic data were colle
cted in 1996 and 1997 for hypocotyl length, percentage of abnormal seedling
s, and sprout yield 6 days after germination at 20 degreesC. Hypocotyl leng
th was determined as the average length from the point of initiation of the
first secondary root to the point of attachment of the cotyledons. The num
ber of decayed seeds and seedlings, plus the number of stunted seedlings (l
ess than 2-cm growth), was recorded a s abnormal seedlings. Seed weight was
determined based on the 50-seed sample. Sprout yield was recorded as the t
otal fresh weight of soybean sprouts produced from the 50-seed sample divid
ed by the dry weight of the 50-seed sample. Four QTLs were associated with
sprout yield in the combined analysis across 2 years. For the QTL linked to
L154 on the Linkage Group (LG) G the positive allele was derived from Pure
unkong (R-2 = 0.19), whereas at the other three QTLs (A089 on LG B1, A668n
on LG K and B046 on LG L) the positive alleles were from Jinpumkong 2. QTLs
conditioning seed weight were linked to markers A802n (LG B1), A069 (LG E)
, Cr321 (LG F) and A235 (LG G). At these four markers, the Jinpumkong allel
e increased seed weight. Markers KO I ln on LG B1, W1 on LG F and A757 on L
G L were linked to QTLs conditioning hypocotyl length; and Bng119, K455n an
d K418n to QTLs conditioning the abnormal seedlings. The QTLs conditioning
sprout yield were in the same genomic locations as the QTLs for seed weight
identified in this population or from previously published research, indic
ating that QTLs for sprout yield are genetically linked to seed-weight QTLs
or else that seed-weight QTLs pleiotropically condition sprout yield. Thes
e data demonstrate that effective marker-assisted selection may be feasible
for enhancing sprout yield in a soybean. The transgressive segregation of
sprout yield, as well as the existence of two QTLs conditioning greater tha
n 10% of the phenotypic variation in sprout yields provides an opportunity
to select for progeny lines with a greater sprout yield than currently pref
erred cultivars such as Pureunkong.