Towards improving resistance of micropopagated bananas to fusarium wilt using bacteria and mycorrhizae, 1: bioassay development
2001
Smith, L.J. | Smith, M.K. | Hamill, S.D. | Hunter, M.N. | Pegg, K.G. | Galea, V.J.
A small plant bioassay was developed using micropropagated banana, to evaluate the potential of biological control agents such as bacteria and VAM [vesicular arbuscular mycorrhizal] fungi, for their effect on Fusarium oxysporum f.sp. cubense (FOC). A slow release fertilizer, Triabon, applied at the recommended rate (0.75 g/L), resulted in a high level of VAM colonization of feeder roots of Lady Finger (AAA) and Williams (AAB) varieties and promoted adequate growth. Nine-week-old micropropagated Lady Finger (AAA) plants that were 10-15 cm in height expressed typical external and internal symptoms of fusarium wilt when inoculated with a spore suspension of FOC (2 x 10**6 spores/mL). External symptoms of leaf yellowing and wilting were observed within 2 weeks and internal discoloration of the roots and rhizome was found after 4 weeks. Disease expression was consistent between replicate plants. In a repeat experiment, external symptoms of fusarium wilt were not observed after nine weeks and the majority of plants were not infected. This bioassay based on the provision of a constant water table within a closed pot would be suitable for studies on the effect of potential biological control agents on FOC in micropropagated banana once inconsistencies in infections are overcome. Investigations are continuing to develop a reliable small plant bioassay
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