TITLE:
Genetic Analysis of Selected Mutants of Cowpea (Vigna unguiculata [L.] Walp) Using Simple Sequence Repeat and rcbL Markers
AUTHORS:
Festus Olakunle Olasupo, Christopher Olumuyiwa Ilori, Esther Adekemi Stanley, Temitope Esther Owoeye, David Okeh Igwe
KEYWORDS:
Cowpea Mutants, Genetic Diversity, rbcL Gene, Sequence Analysis, InDels, Point Mutation
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.9 No.13,
December
26,
2018
ABSTRACT: Genetic diversity
evaluation of mutant lines is essential to facilitate their conservation and
utility in breeding programs. Characterization of plant genotypes using
morphological markers has limitations which make the procedure inefficient.
Application of molecular tools for characterization and diversity assessment
has been found useful to complement phenotypic evaluation of plant population.
Therefore genetic diversity of some cowpea mutant lines was studied using
simple sequence repeats (SSR) markers. DNA barcoding marker,
ribulose-1,5-bisphosphate carboxylase(rbcL) of the chloroplast DNA (cpDNA) was also used for
characterization and identification of the mutants to species level. The mean
polymorphic information content (0.51) obtained from the microsatellites showed
high polymorphism in accessing wide genetic diversity among the mutants and
their parents. Dendrogram generated revealed 8 groups with most mutants
clustered separately from their parents. Sequence analysis revealed
insertions/deletions (InDels)
and base substitutions as the two main classes of mutations induced in the
plastid DNA of the mutants studied. The nucleotide frequencies were 26.95% (A),
34.43% (T), 24.09% (C) and 14.53% (G). A total of 61.38% AT rich region was
identified, while GC rich region was found to be 38.62%. Highest rate of
mutations were observed in region 3 - 4 indicating that the region is less conserved in
cowpea rbcL gene. The present study proved that SSR markers
are useful for the genetic diversity assessment of cowpea mutants. It also
proved the efficiency of rbcL markers in mutants’ identification. The results
indicate that the mutants are valuable genetic resources that have been developed to
widen cowpea genetic base.