In Vitro Inoculation of Asparagus with Conidial Suspension and Culture Filtrate of Fusarium Oxysporum Schlect F. Asparagt

The invitro inoculation technique offers a fast and reliable way to assess susceptibility to fungal infection. This a technique has been used on asparagus tissue culture produced shoots and mature stems. The inocula used were conidial suspension and culture filtrates of Fusarium oxysporum. Post inoculation assessment was carried out as early as 24 hours after inoculation and ran up to 14 days after inoculation (DAI). Inoculation with conidia showed hyphalproduction in less that 24 hours and at 2DAI there is a distinct network of hyphae on the tissue surface. By 6DAI necrosis appeared and at 12DAI, necrosis spread througout the whole stem. In some cases even at 8DAI, extensive mycelial growth on the surface appeared without any apparent necrosis. However when the tissues were cut, reddish stains appeared in subepidermal layers. Penetration of reddish stains appeared in subepidermal layers. Penetration of hyphae rarely occurs direct through the epidermal layers due to well developed cuticle layer. More after, cracks, natural openings and stomates offer easy access to the tissues beneath. Infection also caused dark deposits in the vascular system to form, thus leads to wilting. Inculation with culture filtrates on mature tissues caused chlorosis and death as early as 4DAI. The invitro inoculation can supplement the field disease screening method by hastening the assessment and study of host-pathogen interaction.