Location: Tropical Crops and Germplasm Research
Project Number: 6090-21000-061-007-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 1, 2022
End Date: Oct 31, 2024
Objective:
Coffee fruit rot is a problem worldwide. It is also known as coffee berry disease in Africa where it causes yield losses of up to 80%. The literature points the causal agent to be fungal species in the genus Colletotrichum. However, recent work by ARS and UPR scientists in Puerto Rico shows that species of the fungus Fusarium in association with the coffee berry borer (CBB) insect also play an important role in disease incidence in Puerto Rico. This finding is novel and merits further studies given that Fusarium species are serious pathogens of many crops. This project has the following objectives: 1) identify Fusarium species infecting coffee fruits in Puerto Rico; 2) Identify Fusarium species carried by CBB; and 3) assess phytosanitary risks of Fusarium species isolated from coffee fruits with other Fusarium species isolated from other crops.
Approach:
In order to identify Fusarium species from coffee fruits and CBB insect, at least 150 Fusarium strains will be isolated from green, yellow, red, and mummified coffee fruits at different stages of decay and from adult CBB specimens. Strains will be cultured on potato dextrose agar media and standard morphological structures will be measured and photographed. DNA from pure Fusarium cultures will be extracted and partial sequences of three nuclear genes will be amplified and sequences generated will be used to construct a phylogenetic tree.
Virulence of Fusarium species on coffee fruits will also be tested. For this purpose, representative fungal isolates of all species isolated will be inoculated on green coffee fruits. These tests will determine whether they are primary pathogens or secondary colonizers.
Phytosanitary risks of Fusarium species isolated from coffee will be assessed. Each isolated species from coffee rot tissue having sequences with >99% similarity in National Center for Biotechnology (NCBI) GenBank will be searched and analysed to determine geographical area origin and corresponding host crop. A phylogeography tree will be constructed with Fusarium species isolates from coffee fields in Puerto Rico and Fusarium species from other crops and geographical regions.
