Genetic Diversity Assessment of Bixa orellana L., a Natural Seed Dye Species of the Tropics, using ISSR Markers

Bixa orellana .L is an important dye yielding tree. The bixin content in the seeds yields a red colour pigment in varying colours which is used as dye. The variation in bixin content could be attributed to both environmental and genetic changes. In this study a total of 24 genotypes of Bixa orellana .L were raised from FC&RI, Annatto gene bank of Mettupalayam, India and their genetic diversity were analysed using ISSR markers. Out of 33 primers used, 23 primers were effectively screened for amplification and their polymorphism ranged from 50–100% indicating high genetic diversity among the genotypes. The values of polymorphic information content (PIC) ranged from 0.50–0.60. The other marker traits viz., effective marker ratio, discriminating power and heterozygosity are in higher values revealing the effectiveness of the ISSR markers. The total number of bands varied from 6 to 13. Among all the bands generated, 22 unique bands were detected in eight genotypes, out of which TSMLGB18 produced maximum number of unique bands. The UPGMA clustering pattern revealed that 24 genotypes were divided into seven distinct clusters. The genetic relationship obtained through Jaccard’s similarity co-efficient ranged between 0.57 to 0.88. The result provided valid guidelines for collection, conservation and characterization of Bixa orellana genetic resources.