Assessment of Variability in Sweet Potato (Ipomoea batatas (L.) Lam.) Germplasm Using Morphological and ISSR Markers

Abstract

Fifty two accessions of sweet potato collected from eastern states of India and maintained in the National Active Germplasm Site at ICAR-CTCRI, along with two wild species Ipomoea triloba L. and Ipomoea aquatica Forssk. were evaluated using eighteen vegetative morphological and eleven Inter Simple Sequence Repeats (ISSR) markers. The dendrogram obtained using phenotypic characters separated the genotypes into two major clusters and an outlier at a Euclidean distance of 1.20. The first three principal components of data accounted for 67.50% of the total variance among accessions. Traits like predominant vine colour, leaf lobes type were found to be of great importance in distinguishing the accessions. The cluster diagram based on morphological data revealed that the accessions exhibited greater degree of genetic variation for the 18 different morphological traits observed. According to the morphological data, there were no duplicate accessions and S1439 and S1442 were found to be highly similar among the accessions studied. The hierarchical clustering using on ISSR profile based on Jaccard’s similarity coefficient separated the accessions into three principal clusters at a similarity coefficient of 0.56. The first principal cluster consisted of 37 accessions with many sub-clusters showing high intra-clusteral variability indicating the variability in the sweet potato accessions selected for the study. Accessions collected from the same geographical area were grouped together in a single cluster. The second principal cluster comprised of 15 accessions with one set of two accessions showing 89% similarity, both collected from Bihar. This grouping was similar to that obtained with morphological data. I. triloba L. and I. aquatica Forssk. were grouped as a third cluster showing their species specificity. Mantel test indicated significant correlation between morphological and molecular marker information.