Tropical Race 4 and Race 1 strains causing Fusarium wilt of banana infect and survive in Heliconia species and ornamental bananas
Fusarium wilt of banana (FWB), caused by soilborne Fusarium spp., is a major global threat to the cultivation of bananas. In addition to persistent chlamydospores, weeds are a reservoir of the causal agents. However, it remains unclear whether other Zingiberales species, which are grown in the same geographic regions, also can serve as hosts for Fusarium spp. that cause FWB. Greenhouse assays were conducted to investigate whether Fusarium phialophorum (Race 1; pathogenic to Gros Michel banana) and Fusarium odoratissimum (TR4; pathogenic to Cavendish banana) can infect three Heliconia species, two ornamental banana species or Musa textilis (abaca). Heliconia latispatha, Musa balbisiana, and Musa coccinea displayed external symptoms after inoculation with TR4, while inoculation with Race 1 caused symptoms in H. latispatha, H. psittacorum, M. coccinea, and M. velutina. Isolates recovered from distinct organs of all studied plant species were characterized and re-isolated strains caused FWB symptoms in Gros Michel and Cavendish banana plants, and their rhizome discolored area scores were similar to the reference strains. The susceptibility of some ornamental species and the presence of Fusarium strains as asymptomatic endophytes in others, with remaining pathogenicity, call for a revision of the race nomenclature and the current containment protocols for FWB.