| dc.description.abstract | The export banana industry, heavily reliant on agriculturally intensive monocul- tures of Cavendish cultivars, faces a significant threat from the Fusarium wilt pathogen, Fusarium oxysporum f. sp. cubense tropical race 4 (TR4). Containing Fusarium wilt of bananas (FWB) is challenging due to TR4’s soilborne nature and its persistence in the soil for long periods. Although efforts are underway to develop TR4-resistant marketable bananas, such varieties are not yet available. Furthermore, resistance, productivity, and plant resilience can be reduced by intensive agricultural practices. Therefore, the establishment of FWB integrated management systems is required.
In this study, we evaluated TR4 taxonomy and epidemiology and assessed environmentally friendly strategies for FWB management, with special consideration given to Colombia. The reassessment of the taxonomic classification of TR4 as Fusarium odoratissimum, revealed that the proposed change was premature and potentially problematic for taxonomy users. A genome-wide single nucleotide polymorphism analysis was conducted, giving insight into the relationships among TR4 isolates worldwide. Results indicated two distinct incursions of TR4 into Latin America, with Colombian isolates more closely related to isolates from the United Kingdom and the Middle East than those from Peru.
An evaluation of soil attributes associated with the occurrence of FWB and the efficacy of urea eradication treatment (UET) was performed. Significant changes in soil bacterial community composition linked to areas adjacent to FWB outbreaks were observed. No abiotic attributes were associated with Fusarium oxysporum (Fo) abundance. UET reduced Fo abundance, and soil attributes rapidly returned to levels akin to productive soils.
Indigenous biocontrol agents (BCAs) against TR4 were isolated and evaluated. In vitro tests revealed substantial reductions in TR4 growth. The co-inoculation of Bacillus velezensis B028 and Metarhizium anisopliae F048 reduced FWB severity by up to 80% under greenhouse conditions, although no significant changes in disease incidence were noted.
Finally, the non-target effects of co-cultivating bananas with the potential biocontrol intercrop, Allium tuberosum, on the soil microbiome were investigated under greenhouse conditions. The co-cultivation did not induce significant changes in the soil microbiome, suggesting that previously reported reductions in TR4 abundances are to the allelopathic effect of allium root exudates. Conversely, the cultivation of allium, increases beneficial microbes with biocontrol potential, while bananas fostered plant-growth-promoting microorganisms. This suggests that under crop rotation, FWB reduction might result from changes in the soil microbiome.
This research enhances understanding of TR4 taxonomy, epidemiology, and environmentally friendly FWB management. These insights inform integrated management plans aiming at crop resilience. | en_GB |
