Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: LINKAGES BETWEEN RFLP, RAPD, ISOZYME, DISEASE-RESISTANCE, AND
MORPHOLOGICAL TRAITS IN NARROW AND WIDE CROSSES OF CUCUMBER
LINKAGES BETWEEN RFLP, RAPD, ISOZYME, DISEASE-RESISTANCE, AND
MORPHOLOGICAL TRAITS IN NARROW AND WIDE CROSSES OF CUCUMBER.
Kennard, W., Poetter, K., Dijkhuizen, A., Meglic, V., L, Staub,
J., Havey, M. USDA, ARS, University of Wisconsin, Madison, WI
53706.
A 58 point genetic map was constructed using RFLP, RAPD,
isozyme, morphological and disease resistance markers spanning
766 cM on ten linkage groups for a wide cross (Gyl4 x PI432860)
within cultivated cucumber, Cucumis sativus var. sativus.
Relatively few DNA polymorphisms were detected (around 10% of
probes and primers screened resulted RFLP or RAPD polymorphisms
with 91% and 60%, respectively, segregating in expected ratios at
P < 0.05), agreeing with previous studies documenting a narrow
genetic base for cucumber. A second linkage map was constructed
using RFLP, isozyme, morphological and disease resistance markers
spanning 480 cM on ten linkage groups for a wide cross between
cultivated cucumber and the wild Cucumis sativus var. hardwickii
(Gyl4 x P1183967). Unlinked markers and more linkage groups than
chromosome pairs indicated that both maps are not saturated.
Twenty-one markers segregated in both mapping populations and
regions of colinearity were identified. A 100 point map is under
construction using primarily RAPD markers for two more closely
related cultivated cucumber lines (6421 x H19). The data from
the three maps will be merged using a set of 50 sequence
characterized amplified regions markers (SCARs). Genes
controlling plant height (de), sex expression (F,M), and QTLs for
multiple branching, sequential fruiting and late flowering are
being identified and mapped in the G421 x H19 cross using a
combination of near isogenic lines and bulk segregant analysis.
Markers linked to target traits will be used for marker assisted
selection of potentially high yielding cucumber lines suitable
for once-over mechanical harvesting (i.e., lines with stable
female sex expression, determinate plant architecture, multiple
lateral and sequential fruiting habits, as well as other
horticulturally desirable traits).
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