Use of SSR markers for genetic diversity studies in mulberry accessions grown in Kenya

The knowledge and understanding of the extent of genetic variation of mulberry germplasm is important for conservation and improvement. The objective of this study was to analyze the genetic diversity between and within two mulberry species widely grown in Kenya which include Morus alba and Morus indica. Five individuals per species were genotyped with 13 simple sequence repeat (SSR) markers. The SSR markers presented a high level of polymorphism and detected a total of 35 polymorphic bands and 74.47% polymorphic loci. The mean observed heterozygosity per primer was 0.3670 suggesting a high degree of variation. The analysis of molecular variance (AMOVA) revealed that 95% of the variation was found within the species and only 5% between the species. Principal coordinates analyses (PCOA) clearly distinguished three groups. It was evident from this study that the mulberry accessions did not cluster on the basis of their geographical origin, and neither according to the group of species they fall into. The study showed a close relationship between the two species and therefore mulberry improvement should target sampling more individuals within species rather than among species.