Ram Chandra Jena

Evaluation of genetic diversity among commercial cultivars, hybrids and local mango (Mangifera indica L.) genotypes of India using cumulative RAPD and ISSR markers

An assessment of genetic diversity studies was undertaken to understand the level and pattern of diversity in 65 mango (Mangifera indica L.) genotypes of India including 20 commercial cultivars, 18 hybrids, 25 local genotypes and two exotic cultivars based on qualitative and quantitative fruit characters as well as RAPD and ISSR profiles. A considerable variation was observed in respect of three important qualitative characters namely table quality, fruit attractiveness and storage life of ripe fruits and potentially superior genotypes for the above traits were identified. A wide variation was noticeable regarding metabolite composition of pulp of ripe mango fruit with respect to total soluble solids, total sugar, reducing sugar, acidity, sugar:acid ratio, ascorbic acid and phenolic content. Fifteen RAPD primers yielded 27 monomorphic and 129 polymorphic bands with percent polymorphism averaging 82.7%. Of a total 70 ISSR bands generated from eight ISSR primers, 60 bands (85.71%) were found to be polymorphic. Cumulative band data from these two methods precisely arranged accessions into eight clusters which correspond well with their pedigree relationship. UPGMA dendrograms drawn using RAPD, ISSR and cumulative data showed highly similar grouping of genotypes on the basis of their parental origin. No clear-cut geographical separation was revealed among East, West, North and South Indian mango cultivars by neither of these molecular markers nor their combinations. This supports the common gene pool origin of mango as well as operation of similar selection pressure as the cultivar preferences in these areas are largely similar.

Genetic Diversity Among Some Promising Indian Local Selections and Hybrids of Cashew Nut Based on Morphometric and Molecular Markers

ABSTRACT The present investigation reports an elucidation of genetic diversity among 12 promising Indian cashew nut cultivars, including 9 local selections and 3 hybrids on the basis of morphometric and yield parameters as well as random amplified polymorphic DNA (RAPD) markers. Dice dissimilarity coefficient was used to discriminate cultivars with respect to gross phenotypic characters such as plant growth, flowering, fruit, and nut characters. DNA from these cultivars were subjected to polymerase chain reaction (PCR) using 35 decamer oligonucleotide primers of which 15 primers were able to generate informative polymorphism (average 79.187%). The unweighted pair group method using arithmetic average (UPGMA) dendrogram segregated the cashew cultivars into two main clusters at 0.53 Jaccard’s similarity coefficient. Five different primers were identified with the ability to discriminate eight cultivars based on a unique band pattern. Although both morphometric descriptors and RAPD markers proved their effectiveness for distinguishing the different cultivars in cashew germplasm of India, the superiority of the latter was explicit being more informative as to genotypic discrimination and establishing genetic relationships.