Genetic diversity of common guava in Kenya: an underutilized naturalized fruit species
Citable Link (URL):http://resolver.sub.uni-goettingen.de/purl?gs-1/16525
Introduction – Common guava (Psidium guajava L.) fruit has a significant nutritional and medicinal potential besides its economic importance. Currently, the world guava fruit production is based only on a few cultivars. It is not clear when guava was introduced in Kenya, but the species is currently naturalized. There is no detailed study on guava diversity in Kenya to enable a comparison with other guava-producing countries for purposes of characterization and improvement. Objectives – The main objective of the study was to analyse the genetic diversity and differentiation of guava accessions from four geographically diverse regions of Kenya. Materials and methods – The genetic diversity of 177 guava accessions collected from four regions of Kenya (Coast, Eastern, Rift Valley, and Western) was assessed using 13 simple sequence repeat (SSR) markers. Results and discussion – The neighbour-joining (NJ) phylogenetic tree revealed most accessions generally clustering into multiple weakly supported groups. Only 46 out of 177 accessions were supported by bootstrap values above 50% and clustered in twenty-two groups, each comprising two or three individual accessions only. The principle coordinates analysis (PCoA) did not reveal clear-cut clusters along geographic origins or fruit flesh colour of the samples. The fixation index (FIS) was very high (FIS=0.511), which could be due to a high level of either inbreeding and/or differentiation. The white-fleshed accessions were clustered together with the red-fleshed types, indicative of some degree of genetic similarity, but also pointing to a possibility of shared ancestry between them. Conclusion – For guava conservation and selection for breeding and utilization purposes in Kenya, sampling of many individual accessions covering the geographical range of the species is recommended.