Genetic diversity and population structure analysis in tamarind (Tamarindus indica L.) using SCoT and SRAP markers

Tamarind (Tamarindus indica L.) is a large and long-lived tropical tree. Although the distinctly acidic pulp of its fruit finds multiple applications in nutrition, medicine, and industry, the genetic diversity of tamarind and the identification of unique genotypes suitable for different applications have received little attention. To address this gap, molecular genetic diversity of 91 genotypes of tamarind from different regions in India was assessed using start-codon-targeted (SCoT) markers and sequence-related amplified polymorphism (SRAP) markers. Of the 46 markers tested, 10 SCoT and 10 SRAP markers were polymorphic, and the polymorphic information content values ranged from 0.38 to 0.45 with a mean of 0.40 for both the primers. Genetic relationships among the genotypes investigated using a neighbor-joining tree showed the 91 genotypes to be composed of four distinct clusters, and analysis of population structure showed them to be corresponding to four pure-population groups (the probability score was 0.80 or higher). Principal component analysis of the molecular variance showed it to be along three axes: axis 1 explained 31.83% of the variation; axis 2, 12.40%; and axis 3, 9.99%. The analysis of molecular variance indicated that 2% of the variance was observed among populations, and 10% of the variance was due to the differences among individual plants. Most (88%) of the variation was found within individuals. The study demonstrated significant genetic diversity among the genotypes of tamarind, which can help in targeted breeding not only for overall improvement of the crop but also for the enhancement of specific traits. The identified markers can serve as valuable genomic resources for the conservation and utilization of tamarind.