4.1. Materials

Two banana cultivars, Musa spp. AAA cv. “Baxijiao” and “Yueyoukang 1” were used in this study. “Yueyoukang 1”, a cultivar from Cavendish selection GCTCV-218, is highly resistant to Foc4 (disease incidence in the field is under 5%) while “Baxijiao” is highly susceptible to this pathogen (with disease incidence of 44.4% in the field [43]).

Single-spore cultures of highly virulent Foc4 were used in the present study for banana inoculation. The pathogen cultivated on solid potato dextrose agar (PDA) medium (200 g/L patato + 20 g/L dextrose + 13 g/L agar) and kept at 4 °C for two cycles was activated on the fresh PDA medium and cultivated at 28 °C for 3 days in dark before transferring to the liquid potato lactose medium (200 g/L patato + 20 g/L lactose + 13 g/L agar) to produce spores. After 7-day-culture on a shaker rotating at 140 rpm, spore suspension was ready for use.