Histopathological Profiling of Banana Varieties Infected with Fusarium oxysporum f. sp. cubense Tropical Race 4

Abstract

Fusarium wilt disease has been a major threat to the banana industry in the Philippines and efforts are of utmost importance to combat it. The present study evaluated the histopathological characterization of Fusarium oxysporum f. sp. cubense Tropical Race 4 infecting two susceptible varieties, the Lakatan and Cavendish cv. Gran Naine banana seedlings. This is to understand the pathogen’s aggressiveness and the host plant response mechanism. The study was conducted using histopathological profiling techniques, including pathogen isolation, pathogenicity testing, and tissue analysis. The pathogenicity test for the FocTR4 isolates has demonstrated an external symptom of yellowing on the older leaves and pseudostem splitting, with an internal manifestation of corm and vascular discoloration. Histological examination of the FocTR4-infected tissue exhibited massive colonization of fungal mycelia to the xylem vessels and was able to produce a chlamydospores and microconidia structure. Moreover, both varieties exhibited a defense response to the pathogen attack by the production of its phenolic compounds which is more evident in the Lakatan variety. These findings emphasize the virulence nature of the FocTR4 and highlight the importance of developing resistant cultivars and integrated management strategies. Further research should focus on the molecular level in understanding the histopathological characterization of FocTR4-infected banana varieties at the nursery and field conditions.