Assessment of the Ploidy Level Diversity by Chloroplast Counts in Stomatal Guard Cells of Potato (Solanum tuberosum L.) Mutants

Abstract

Aims: Potato (Solanum tuberosum L.) is the most important staple food in the world and plays an important role in food and nutritional security. Induced mutation generates variation within potato germplasm to widen the genetic base for breeding purposes. Polyploidy modifies both the genotype and phenotype of an organism, generating diverse changes that consequently transform the potato production. Potato has chromosomes with different ploidy levels which can be determined by counting chloroplasts in stomatal guard cells. Study Design:  The study was carried out in completely randomized block design. Place and Duration of Study: Department of Biotechnology, University of Eldoret, between February 2015 and July 2016. Methodology: The study involved 163 potato mutants developed from three commercially grown Kenyan potato varieties; Asante, Mpya, and Sherekea irradiated using gamma rays from 60Co source under different dose rates. Three middle leaves of greenhouse-grown plants were randomly selected for chloroplast counts in ten pairs of stomata guard cells on the lower surface of the leaf. Data on the number of chloroplast counts per mutant was calculated as a percentage of the parents or control and descriptive analysis. Results: The results indicate that the number of ploidy level distribution was decreasing in diploids and triploids and were increasing in tetraploids from M1V1, M1V2 to M1V3 in all the potato mutant populations. Conclusion: This shows that mutation induction generates genetic variations from which desired mutants may be selected based on the appropriate breeding strategies.