Intraspecific variations in cardamom (Elettaria cardamomum Maton): assessment of genomic diversity by flow cytometry, cytological studies and ISSR analysis

BACKGROUND: The main goal of the work was to analyse intraspecific variation in Elettaria cardamomum Maton (cardamom) using genome size, cytological studies and molecular marker data. Nuclear DNA content and molecular marker details furnish data on genome size and genetic diversity respectively among the studied accessions and both complement each other for evolutionary and taxonomic studies. RESULTS: The relative 2C genome size and total number of base pairs of cardamom was determined through flow cytometric analysis using propidium iodide staining. The nuclear DNA content was estimated in various sections of the species representing individuals from wild and cultivar genotypes following Zea mays L. CE-777 (2C = 5.43 pg) as internal reference standard. Chromosome number from growing root tip was examined following standard protocols. Twenty-six ISSR primers that generated polymorphic bands were used for genetic diversity analysis of the thirty accessions of cardamom. Estimated nuclear 2C DNA content ranged from 2.57 to 3.22 pg demonstrating 1.25-fold variation. The mean amount of 2C nuclear DNA of the cardamom was calculated as 2.87 pg which is equivalent of 2806 Mbp as the diploid genome size. The chromosome number was found to be 2n = 48. Among the thirty accessions of cardamom studied using ISSR markers, C53 (feral from Bonacaud) showed a very prominent level of genetic diversity and was lowest for C96 (Avinash-I, a released variety from Indian Institute of Spices Research, Kozhikode). CONCLUSION: These analyses revealed the existence of genetic variability within the studied cardamom accessions. The plant specimens also differed significantly in their genome size. However, the genetic variability parameters did not show any correlation with genome size.