Inter-Simple Sequence Repeat Markers Reveal a Moderate Genetic Diversity among Fusarium Species Causing Common Bean Root Rot in Uganda

Abstract

Aims: The present study aimed to determine the genetic diversity and population structure of Fusarium species causing common bean root rot in Uganda Study Design:  The study used isolates from a previous disease survey in Uganda Place and Duration of Study: The isolates were collected from 6 different agro-ecological zones of Uganda. Isolation was conducted at the legumes pathology laboratory of the National Agricultural Research Organization at Namulonge, Kampala. The isolates were collected in 2019. Methodology: DNA was extracted from 101 Fusarium species isolates using a modification of the cetyltrimethylammonium bromide protocol. Seventeen inter-simple sequence repeat primers were used in the polymerase chain reaction. The bands were scored for presence and absence using 1 and 0, respectively. The genetic diversity and population structure were determined using parameters such as polymorphic information content, allele divergence frequency, Principal component analysis, and admixture analysis. Analysis of molecular variance was also conducted. Results: The average polymorphic information content of the isolates was 84%. The average Wright's fixation index (Fst) and expected heterozygosity were 0.2. The result of the analysis of molecular variance revealed that 0.2% of the variation was between the agro-ecological zones, while 99.8% of the variation was within agro-ecological zones. Admixture analysis showed that the isolates have an admixed ancestry. Conclusion: Since the isolates from the different agro-ecological zones were similar, released varieties may not face extreme variants when they are planted in agro-ecological zones where they were not screened.