Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 40pg1
RAPD ANALYSIS IN TETRAPLOID AND HEXAPLOID WHEATS.
C. P. Joshi and Henry T. Nguyen, Plant Molecular Genetics
Laboratory, Texas Tech University, Mail Stop 2122, Lubbock, TX
79409, USA.
Development of a high-density genetic linkage map of
cultivated wheats using conventional molecular markers has
substantially lagged behind the other major food crops due to the
limited levels of polymorphisms. Recently, RAPDs (Random
Amplified Polymorphic DNAs) have been shown to provide a powerful
alternative to alleviate these problems. For the construction of
a genetic linkage map in tetraploid wheats, we plan to use a
strategy of intersubspecific crosses between the most dissimilar
wild and cultivated tetraploid wheats which are easy to hybridize
and result in fertile progeny. An assessment of the level of
RAPDs among different accessions and varieties of wild and
cultivated tetraploid wheats is required to fulfill this
objective. We present here the data obtained using RAPD analysis
of 40 arbitrary primers in 20 accessions of wild tetraploid emmer
wheats (Triticum turgidum L. ssp. dicoccoides) and 10 genotypes
of cultivated tetraploid durum) wheats (Triticum turgidum L.
ssp. durum) selected from geographically diverse locations. We
have observed a higher level of polymorphism (88% of the
amplified fragments) among different accessions of wild emmer
wheat from Israel, Turkey and Jordan than the group of cultivated
American, Turkish and Syrian durum wheats which showed 68 % of
the amplified fragments polymorphic. These data have been used
to generate a dendrogram suggesting the genetic relationships
among these genotypes, and the most dissimilar genotypes are
identified for further work. The second objective of this study
was to assess the suitability of RAPD technique for the detection
of polymorphism among 15 varieties of common bread wheat
(Triticum aestivum L.). Out of 109 amplified fragments, 71 (65%)
were polymorphic in these wheat cultivars. These results allowed
development of a dendrogram suggesting genetic relationships
among these genotypes and in the identification of suitable
parents for the development of a mapping population in the
future. Moreover, spring and winter wheats were clustered
together in this dendrogram based on Jaccard's coefficients.
These results will be useful in the future for the development of
a genetic linkage map in wheat.
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