Evaluation of banana cultivars for resistance to Fusarium wilt Tropical Race 4

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc) and in particular Tropical Race 4 (TR4), is one of the key constraints for sustainable development of the banana industry. Developing a rapid evaluation methodology for screening banana cultivars for their host reaction to TR4 in the greenhouse will provide a basis for further cultivar screening and improvement for TR4 resistance in field trials. We evaluated ‘Brazilian’ (AAA), ‘Guijiao No. 1’ (AAA) and a new cultivar ‘Yunjiao No. 1’ (AAA) in the greenhouse. The tested materials were inoculated with Foc TR4 wild isolate (15-1). The disease index was calculated for both leaf and corm symptoms, and real-time quantitative PCR was conducted to analyze the amount of TR4 pathogen content in corm and soil. In three independent experiments, ‘Yunjiao No. 1’ showed the best performance based on the plant growth and disease index at 25 and 45 days after pathogen inoculation. The performance related to TR4 resistance from strong to weak was: ‘Yunjiao No. 1’>‘Guijiao No. 1’>‘Brazilian’. There was no significant difference in the pathogen DNA content of the inoculated soil among the different banana cultivars tested. The pathogen DNA content in the corm of the ‘Yunjiao No. 1’ was significantly lower than that in ‘Brazilian (P<0.05). Using the rapid evaluation methodology for TR4 resistance of banana cultivars in the greenhouse, we found that ‘Yunjiao No. 1’ had the best performance compared with the other two cultivars. Therefore, it is considered worthwhile to further this study by continuously selecting more resistant plants in heavily TR4-infested fields.