Fusarium species associated with waterberry (Syzygium cordatum) floral
Research project of Marija Kvas (MSc student) being supported through the
Waterberry, also known as umdoni (Syzygium cordatum), is a native tree of Southern
Africa that is commonly found near streams, forest margins or in swampy spots. This
evergreen tree has white, fluffy flowers that bloom from August to November. Its fruit is
an edible berry that turns dark-purple when ripe. In rural areas the tree is used as a
remedy for stomachache, diarrhea and tuberculosis.
Recently, numerous trees with malformed inflorescences have been observed (Figure).
The affected inflorescences are abnormally enlarged, branched and heavy. They also
bear large numbers of flowers. With time these malformed inflorescences dry out without
ever bearing fruit. Similar symptoms are also associated with mango (Mangifera indica).
Mango inflorescences malformation is caused by Fusarium mangiferae, which is a
member of the Gibberella fujikuroi species complex. Therefore the aim of this project is
to identify and characterize various Fusarium species associated with malformed
waterberry inflorescences, by primarily focusing on species from the G. fujikuroi
Fusarium isolates were obtained from malformed and healthy inflorescences from
various locations throughout South Africa. These are then identified using morphological
and DNA-based approaches. For the morphological identifications, the fungi are
examined microscopically and traits such as shape and size of macro- and microconidia
as well as presence of mono-, polyphilaides and chlamydospores are evaluated. For the
molecular identifications, species differences are detected using the DNA sequence for
the gene encoding EF-1 , which are compared to those in a public domain database.
Thus far, numerous saprophytic Fusarium species such as F. oxysporum, F.solani,
F.equiseti, F. pallidoroseum
has been identified. A number of novel lineages in the G.
complex have also been identified. These include species that are closely
related to F.sacchari, F.proliferatum, F.udum as well as several species that appear to be
completely unique and as yet undescribed. Future work will include studies on the
pathogencity of the various Fusaria isolated from waterberry, as well as a description of
new Fusarium species.
Figure. Healthy vs. malformed waterberry inflorescences.