Analysis of Genetic Variability of Potato Induced Mutants Using Simple Sequence Repeat (SSR) Markers

Abstract

Aims: Potato (Solanum tuberosum L.) is ranked fourth amongst the world’s major stable food crop and second in Kenya after maize and thus plays a vital role in food and nutrition security and sustainable development. Despite its importance, potato production in Kenya is still low due to abiotic and biotic constraints. Traditional breeding and improvement have been difficult due to the narrow genetic diversity of the crop owed to the complex tetrasomic inheritance patterns. Induced mutation has been used to generate genetic variations in potato from which desired putative mutants are selected. In most cases the level of genetic variability is not known. The objective of this study was to determine the genetic variability of potato mutants using SSR markers. Study Design: The study involved three potato varieties; Asante, Kenya Mpya and Kenya Sherekea which are high yielding and commercially grown varieties in Kenya. Place and Duration of Study: Sample: They were irradiated at different dose rates of gamma rays at Co60 source at FAO/IAEA laboratories, Seiberdorf Austria in 2014. A total of 163 mutants were advanced to M1V4 generation at the University of Eldoret between 2015 and 2018. Methodology: Genomic DNA was extracted to assess the diversity with 20 SSRs markers. Results: All the 20 SSR primers were polymorphic with 6-19 bands amplified per primer and marker STM5127 showed the highest allele number (19) using PowerMarker software. The STRUCTURE analysis suggested that the potato mutants were clustered into six sub-populations based on the unweighted pair-group method of arithmetic averages (UPGMA) thus, the accessions were divided into three major clusters. Analysis of molecular variance (AMOVA) indicated that 8.6% of total molecular variance was attributed to diversity among sub-populations, while 91.4% of variance was associated with differences within sub-populations. Conclusion: This study highlights the most comprehensive investigation of the genetic diversity and population structure of potato mutants, and provides valuable information for genetic improvement, and systematic utilization.