Abstract:
For decades, Xanthomonas vasicola pv. musacearum (Xvm) has been an economically
important bacterial pathogen on enset in Ethiopia. Since 2001, Xvm has also been
responsible for significant losses to banana crops in several East and Central African
countries, with devastating consequences for smallholder farmers. Understanding
the genetic diversity within Xvm populations is essential for the smart design of
transnationally reasoned, durable, and effective management practices. Previous
studies have revealed limited genetic diversity in Xvm, with East African isolates from
banana each falling into one of two closely related clades previously designated as
sublineages SL 1 and SL 2, the former of which had also been detected on banana
and enset in Ethiopia. Given the presumed origin of Xvm in Ethiopia, we hypothesized
that both clades might be found in that country, along with additional genotypes
not seen in Central and East African bananas. Genotyping of 97 isolates and
whole-genome sequencing of 15 isolates revealed not only the presence of SL 2 in
Ethiopia, but additional diversity beyond SL 1 and SL 2 in four new clades. Moreover,
SL 2 was detected in the Democratic Republic of Congo, where previously SL 1 was
the only clade reported. These results demonstrate a greater range of genetic diversity
among Xvm isolates than previously reported, especially in Ethiopia, and further
support the hypothesis that the East/Central Africa xanthomonas wilt epidemic has
been caused by a restricted set of genotypes drawn from a highly diverse pathogen
pool in Ethiopia.
