Antifungal Defensins In Controlling Panama Wilt of Banana Fusarium oxysporum f.sp.cubense

Fusarium oxysporium f.sp. cubense causes vascular wilt and root rot in banana plantations at elevated temperatures. Fusarium oxysporium f.sp. cubense can persist in affected fields for an extended period of time on plant stubbles as macro conidia or even survive on soils as dormant chlamydospores in the absence of a suitable host plant. An in vitro antifungal assay was conducted to find the efficacy of defensin (an antifungal protein) from M. truncatula against F. oxysporium f.sp. cubense strains viz., FGSC # 8359 (Australia), FGSC # 8361 (Australia), FGSC # 8363 (MALI), FGSC # 8368 (Taiwan). In vitro antifungal assays using twofold serial dilutions of each defensin (Def1 and Def4) were carried out and Bright-field images were made using the transmitted light channel in a Zeiss LSM 510 META confocal microscope. Fungal growth inhibition was also quantitated spectrophotometrically 12 h ,24 h ,36 h ,48 h after the addition of each defensin (2 μM-20 μM). From the results, it has been postulated that the MsDef1 and MtDef4 have a biphasic effect on the membrane permeabilization of FOC depending on the defensin dose.

Author(s): Raju Radhajeyalakshmi, Yiji Xia and Dhilip Shah

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