Assessing genetic diversity of indigenous turmeric (Curcuma longa L.) through inter-simple sequence repeat (ISSR) markers

Turmeric (Curcuma longa L.), native to Southeast Asia, is renowned for its therapeutic properties, primarily due to its rhizomes containing various secondary metabolites, including the prominent compound curcumin. This study aimed to evaluate the genetic diversity among 35 turmeric genotypes from different geographical regions using Inter-Simple Sequence Repeat (ISSR) markers. Out of 116 amplified products, 110 (94.82%) were polymorphic, indicating significant genetic variation, while 6 (5.17%) products were monomorphic. The ISSR primer pairs generated between 8 to 11 bands each, averaging 9.67 bands per pair. Seven markers exhibited the highest polymorphism (100%), while UBC 850 showed the lowest (81.82%). Polymorphism Information Content (PIC) ranged from 0.18 to 0.46, averaging 0.33. Resolving Power (RP) varied from 5.66 to 11.49, averaging 8.20. Effective Multiplex Ratio (EMR) values ranged from 8.44 to 25.45, with an average of 18.15. Marker index values ranged from 2.88 to 7.44, averaging 5.92, demonstrating the primers' effectiveness in genetic diversity research. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis based on ISSR primers grouped the 35 turmeric genotypes into four main clusters. Cluster I, sourced from Kerala, includes 15 accessions divided into four subclusters. Cluster II has three accessions: CIM-Pithambar and ACC Pratibha in one subcluster, and Suguna in another. Cluster III consists of Suvarna and Ladaw in one group, and Lasein and Lakadong in another, with three accessions from the northeastern region and one from Kerala. Cluster IV, the second-largest, includes 13 accessions from Karnataka, Kerala, Uttar Pradesh, Assam, and Maharashtra. These clusters highlight the genetic diversity and geographical distribution of turmeric accessions.