Determination of Genetic Diversity of Tamarind (Tamarindus indica) Accessions in Eastern Region of Kenya Using Inter Simple Sequence Repeat (ISSR) Markers

Abstract

There is scanty information on tamarind’s genetic diversity in Easter Kenya. The objective of this study was to determine the genetic diversity of 64 tamarind accessions from Eastern Kenya using 12 Inter Simple Sequence Repeat (ISSR) markers. DNA was extracted from the young apical leaves using modified CTAB method and amplified using standard PCR.  The data collected were scored as presence (1) or absence (0) of bands then compared to the 100bp ladder and analyzed using GeneAlex and R softwares. Only seven primers produced reproducible bands. A total of 46 alleles were produced for the 7 loci with an average of 6.6 per loci. Polymorphic information content (PIC) varied from 0.72 to 0.89 and genetic diversity varied from 0.74 to 0.9. The ISSR markers revealed effective polymorphism of 40.87 to 99.46% and the band  sizes varied from 100 to 1000 bp. Analysis of Molecular Variance (AMOVA) depicted high variation within the tamarind populations at 90% and the least variation of 10% among the population. The first 3 components of Principal coordinate analysis (PCoA) contributed 40.83% of the total variation. Hierarchical cluster analysis grouped the tamarind accessions into seven major distinct groups. Tamarind accessions were different within counties with minimal variations among counties, proving that genetic diversity exists among the tamarind accessions in the Eastern region of Kenya. High genetic diversity was evident among Embu accessions and least among Masinga accessions. Diversity in tamarind can be utilized in marker-assisted breeding and primer ISSR17899A and ISSRHB11 can be explored in studying genes that code for various traits in tamarind accessions.