Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 99pg1
MOLECULAR ANALYSIS OF A POLYMORPHIC DNA REGION TIGHTLY
LINKED TO THE SUPERNODULATION (NTS) LOCUS OF SOYBEAN.
Alexander Kolchinsky, Debbie Landau-Ellis, Sieglinde
Angermuller, Joanna Deckert, Roel Funke and Peter M. Gresshoff,
Plant Molecular Genetics and the Center for Legume Research, The
University of Tennessee, Knoxville, TN 37901-1071.
The cloned molecular marker pUTG-132a, known to be tightly
linked to the supernodulation (nts) locus of soybean
(Landau-Ellis et al, Mol. Gen. Genet. 228:221-226, 1991; Mol.
Plant-Microbe Inter., 1992, in press) was restriction mapped and
partially sequenced. PCR primers were designed to generate a
PCR-based polymorphism between G. max (nts) and G. soja (wild
type). PCR amplifications of heterozygotes revealed unexpected
bias towards the shorter PCR product. The cause of the RFLP
originally used to map the nts locus was a 0.8 kb deletion,
removing both an nternal DraI restriction site as well as one of
the PCR primer sequences. A genomic library of soybean DNA
(cultivar Bragg) in lambda phage was screened for clones
homologous to pUTG-132a. The same PCR primers were used to
screen the library. The restriction map of lambda UT-a confirms
the map deduced from hybridizations with genomic DNA. A large
segregating F2 population of an nts x wild type cross was
analyzed using a fast PCR test and no recombinants between pUTG-a
and the nts locus were found. Together with previous data, this
result puts the upper limit of the genetic distance between the
nts locus and pUTG-a marker at 0.3 centimorgans. Physical
mapping in the three-marker pA-36 cluster, ten centimorgans
distant from the nts locus, shows that one centimorgan in the
vicinity of these molecular markers equals 550 kb. Therefore,
the pUTG-a marker is a valuable starting point for
positional cloning of the nts locus.
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