Diversity and Distribution of the Banana Wilt Pathogen Fusarium oxysporum F. Sp. cubense in China

Abstract

Fusarium oxysporum f. sp. cubense (Foc) causes Fusarium wilt, a lethal disease that results in devastating economic losses to banana production worldwide. The pathogen originates from Asia where it evolved with its host, the wild banana plant Musa acuminata. Foc consists of three races, eight lineages and 24 Vegetative Compatibility Groups (VCGs). Most damage is caused by Foc tropical race 4 (TR4), which occurs exclusively in Asia. China is the biggest producer of Cavendish bananas (AAA) in the world, with plantations covering approximately 372.4677×103 hectares constituting up 90% of banana production, with the rest made up of Pisang Awak (ABB) and Dajiao or Plantain (AAB) bananas. In this study, 80 Foc isolates from six production areas were collected from diseased banana cultivars in China. These isolates were all single-spored and characterized to lineage level using five restriction enzymes while VCG identity was determined by generating nit-mutants, and pairing these mutants with a VCG tester set for Foc. To determine the occurrence of Foc TR4 in China, all isolates were screened with a newly developed Foc TR4-specific primer set. All the Foc isolates were also inoculated on Cavendish, Pisang Awak and Dajiao bananas for pathogenicity testing. Our results showed that Foc in China was highly diverse, as five of the eight lineages and 11 of the 24 known VCGs could be determined. The Foc TR4-specific primer set was highly specific for detecting VCG 01213/16, and could be used in diversity studies to rapidly identify this VCG complex. The majority of the isolates from China were identified as Foc TR4 (VCG 01213/16), and this VCG was found in four of the five production areas. Species of Fusarium other than F. oxysporum were non-pathogenic to banana. The selection of Foc-resistant banana clones, and the development of appropriate disease management strategies for Fusarium wilt of banana in China, is urgently required