Tropical Race 4 and Race 1 strains causing Fusarium wilt of banana infect and survive in Heliconia species and ornamental bananas

Abstract

Fusarium wilt of banana (FWB), caused by soilborne Fusarium lineages, 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 strains that cause FWB. Greenhouse assays were conducted to investigate whether a Race 1 strain (pathogenic to Gros Michel banana) or Tropical Race 4 (TR4) (pathogenic to a plethora of banana varieties, including Cavendish bananas) can infect three Heliconia species, two ornamental banana species or Musa textilis (abacá). 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 were recovered from symptomatic and asymptomatic plants and were subsequently characterized and used to inoculate Gros Michel and Cavendish banana plants. They caused the typical FWB symptoms in these varieties, and the scores for discolored rhizome area were similar to those caused by the Race 1 and TR4 reference strains. These data call for a revision of the race nomenclature of FWB pathogens and adjustment of the current containment protocols.