Randomly primed improved PCR approach for genetic characterization and identification of Cymbopogon germplasms

Among monocots forming the grass family (Poaceae), Cymbopogon is one of the most important aromatic essential oil yielding genera. Genetic characterization is very important for proper utilization and improvement of the oil grasses. An improved random amplified polymorphic DNA (RAPD) analysis where touchdown polymerase chain reaction with prolonged RAMP time has been used to characterize the genetic variation in ten Indian elite cultivars of Cymbopogon aromatic grasses of essential oil trade types of Citronella, Palmarosa and Lemongrass. The total of 203 amplification products was scored using 23 RAPD primers, exhibiting an overall 92.61% polymorphism. Polymorphic information content (PIC), effective multiplex ratio (EMR), marker index (MI) and resolving power (RP) averaged 0.374, 7.69, 2.92 and 5.15 per primer, respectively, showing the high efficiency and reliability of the markers used. Also, RAPDs of diagnostic and curatorial importance were discerned as 'stand alone' molecular descriptors for cultivar and species (biotype) identification. The order of the average value of Jaccard's coefficient of similarity was found to be C. winterianus (0.890) > C. flexuosus (0.657) > C. martinii (0.425). The present study confirms the significance of the improved RAPD method in genetic characterization of Cymbopogon sp. and can be employed for efficient identification, conservation and utilization of germplasm resources for plant improvement through conventional as well as molecular breeding approaches.