Population structure of Garcinia kola in Central region of Cameroon

Bc. Irikidzai Prosper Chinheya, BSc

Master's thesis

Abstract:

Garcinia kola is a multipurpose fruit tree species indigenous to West African communities, where it is of significant ethnomedicinal, cultural and economic importance. Faced with the threat of declining population numbers, the species was selected for conservation and participatory domestication programmes however, a lack of adequate information on genetic diversity is widely reported as a limiting factor in both processes. The aim of this study was to assess the genetic diversity of G. kola populations in the Central region of Cameroon using Amplified Fragment Polymorphism (AFLP) markers. Genomic DNA was extracted and then digested with MseI and EcoRI endonucleases. From an initial 24 primers, four high-performing primer combinations were selected to assess genetic diversity within and among eight provenances of G. kola. A total of 1176 fragments were amplified with 98.6 % polymorphism at the species level and a mean number of 261.9 fragments per individual. The computed values for Nei's gene diversity within populations (Hj), Total gene diversity (Ht), and the Wright's fixation index (FST) were 0.1894, 0.1922 and 0.0145 respectively. The obtained results revealed a higher genetic diversity within the assessed populations than among them. Bayesian analysis of sampling groups revealed the existence of two differentiable but admixtured genetic clusters, implying a weak population structuring. Attempts to assess for correspondence between clustering and geographic distances revealed no clear patterns. Most of the outcomes of this study were comparable to those of Benin G. kola populations assessed using RAPD markers. The study revealed that AFLP markers are a useful tool for assessing the genetic diversity of G. kola. Results suggest possible human-mediated gene flow events, potentially attributed to the selection of kernels for trade or natural selection through the adaptation of the species to local environmental. This study may open the door for advancing participatory tree domestication (PTD) and conservations programmes within the study area. However, it is recommended that initiatives be undertaken to safeguard the existing genetic diversity such as the use of gene banks, sustainable utilisation of genetic diversity in PTD or the protection of important individuals within their stands.

Keywords

AFLP marker, Agroforestry, AFTP, Bitter kola, Genetic diversity, Provenance, Tree domestication

Language used: English

Date on which the thesis was submitted / produced: 19. 4. 2021

Thesis defence

• Date of defence: 14. 9. 2020
• Supervisor: doc. Ing. Bohdan Lojka, Ph.D.

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme / field:
Tropical Agriculture / Tropical Crop Management and Ecology