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The molecular markers had been developed as a powerful tool for
the studies in plant genetics and breeding. There are two
types of molecular markers : one is restriction fragment length
polymorphism (RFLP) marker, and the other is random amplified
polymorphic DNA (RAPD) marker. In order to obtain the RFLP
markers, it should take a long time and spend much resources to
construct and screen a genetic library. However, since the
polymerase chain reaction (PCR) technique was developed, it
has revolutionized the RAPD marker production. RAPD markers
are polymorphic DNA segments separated by gel electrophoresis
after PCR amplification using random primers. Genetic analysis
with RAPD markers is fast and involves no radioactivity and
hybridization. For our current sorghum RFLP map construction,
we had screened the informative probes from a PstI and a HpaII
genomic libraries. In this study, we exploited the
availability of using polymorphic DNA segments appeared in RAPD
analysis as probes in RFLPs. Two sorghum parents, V-3 and
V-160, were used as sources of DNA. We had screened out 192
amplified segments in 221 arbitrary 10-mer primers. And 142 of
them had been used in RFLP analysis. Most of them were with a
fragment size larger than 1.0 kb and shown to be multiple
copies. There were 54 segments shown to be suitable as RFLP
probes in these 142 segments. To explore the features of RFLP
in sorghum, the relationship between the probability that a
given enzyme detected polymorphism with a given probe in this
study and the number of other enzymes detecting polymorphism
with the same probe was plotted for regression. The result of
regression suggested that insertion/ deletion was the major
mechanism for generating RFLPs in the sorghum genome, however,
the base replacement was not excluded.
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