Assessment of molecular diversity in Elite Sweet Orange (Citrus sinensis L. Osback) accessions using RAPD markers

Random amplified polymorphic DNA (RAPD) markers were used to estimate the genetic diversity among 27 elite sweet orange accessions maintained at the Citrus Research Station (AICRP on citrus), Tirupati. The 52 decamer primers generated 469 randomly amplified DNA fragments, of which 292 were polymorphic (62.26%). The similarity indices measured based on Jaccard similarity coefficient ranged from 0.52 to 0.80, which showed the presence of low to moderate diversity among 27 sweet orange accessions. Based on UPGMA cluster analysis, these accessions grouped into two main clusters. All 26 sweet orange accessions formed a major cluster. HS-3 accession having its clear genetic identity formed another cluster with the rest of the sweet orange accessions. The sweet orange accessions with great economic importance viz., Jaffa, Blood Red Malta, Mediterranean Sweet, Hamlin Sweet, Valencia Late, Pineapple and Kodur Sathgudi showed complete genetic similarity. RAPD analysis showed that most of the accessions of sweet orange were closely clustered, with relatively high genetic similarity (0.75), suggesting that the genetic base of domesticated sweet orange is quite narrow.