MSc

Sweet potato (Ipomoea batatas (L.) Lam) is one of the major tuber crops
in Asian countries including India, yet the interrelationship and genetic variability
among the cultivar and its crop wild relatives remain unclear. The present study
utilised 12 simple sequence repeats (SSR) marker for analyse the degree of
genetic diversity and relationship within and between 20 sweet potato accessions,
23 wild Ipomoea species and two Merremia species.
The SSR primers produced 84 polymorphic alleles within the range of
105-393 bp. That showed an average polymorphism of 94.5%. The average PIC
value of 0.67 showed that all the primers were polymorphic in nature. Similarity
coefficient based dendrogram and PCA scatter plot clearly differentiated all the
cultivars and wild species. This dendrogram helped to identify the close
relationship of cultivars with I. triloba and I. trifida at a similarity index of 0.75.
The dendrogram based on the SSR molecular data shows high degree of
genetic variability within and between hexaploid sweet potato and diploid wild
species, whereas lower within the cultivars, which shows that there is a high level
of genetic diversity exist within the Ipomoea species.
The results supported the current taxonomical position of M. dissecta as
Merremia species whereas opposed the taxonomical position of M. vitifolia as
Merremia as this study revealed more similarity to Ipomoea than Merremia
species. The similarity coefficient varied from 0.37 to 0.96 indicating high
variability in the genotypes that were included for the present investigation.