02770naa a2200205 a 450000100080000000500110000800800410001910000160006024501300007626000090020652020570021565000110227265000220228365000140230570000170231970000170233670000240235370000190237777301680239616557622010-02-04       2009    bl uuuu     u00u1 u    #d1 aDITA, M. A.  aA greenhouse bio-assay for the Fusarium oxysporum f. sp. cubense (Tropical Race 4) X banana (Cavendish subgroup) interaction.  c2009  aSeveral disease resistance screening protocols for fusarium wilt of banana (causal agent Fusarium oxysporum f. sp. cubense-foc) under greenhouse conditions have  been reported. However, a standard and worldwide accepted methodology is still undefined. A standardised greenhouse bioassay for this pathosystem is necessary for the identification of resistant banana genotypes and for detailed plant-pathogen interaction studies. This became especially important with the advent of tropical race 4 ( TR4), which is a significant threat for the global Cavendish-based banana export industry. Thiswork aimed to establish a reliable and rapid greenhouse biossayfor foc with a focus on the TR4- cavendish interaction. Using a doublepot system, hardened 3-months-old tissue-culture plants of 'Grand Naine' (AAA, Cavendish subgroup) were, separately, inoculated with three isolates, belonging to the Vegetative Compatiblility Group (VCG) 01213 and considered as TR4, and one isolate, ranked as race 1 with known pathogenicity on 'Silk' (AAB). Plants were inoculated by root dipping (30 minutes, 105 conidia/mL) and then transferred to pots partially filled with sand supplemented with 20 maize kernels, previously colonised with foc for 10 days. In TR4-inoculated plants, first symptoms appeared at 7 days after inoculation (dai) showing the typical external (yellowing) and internal (rhizome discoloration) symptoms at 14 dai. At 40 dai, TR4-inoculated plants showed severe wilting and internal necrosis even in the pseudostem. No symptoms were observed in plants inoculate with the race 1 isolate. All the TR4 isolates caused similar symptoms, and no differences regarding incubation period or severity were observed. In addition, all TR4 isolates were successfully recovered from the symptomatic rhizomes on Komada's medium. These results suggest that the bio-assay here described is suitable to screen banana germplasm for TR4 resistance, to discriminate Foc races and to help studies to elucidate the defence mechanism underlyng the Foc-banana interaction.  aBanana  aDoença de Planta  aFusariose1 aWAALWIJK, C.1 aPAIVA, L. V.1 aSOUZA JUNIOR, M. T.1 aKEMA, G. H. J.  tIn: ISHS/PROMUSA BANANA SYMPOSIUM, 2009, Guangzhou, China. Global perspectives on asian challenges: programme and abstracts. Guangzhou: ISHS: Promusa, 2009. p. 45.