Rapid Screening of In-Vitro Regenerated Plantlets of Four Nigerian Cowpea Varieties to Artificially-Inoculated Fungal Wilt Pathogen

Tissue culture technique provides a rapid means of studying plant-pathogen interaction in a controlled environment with further advantage of saving time and resources. Embryonic axes of three local cowpea (Vigna unguiculata (L.) Walp) varieties (Oloyin, Ife-Brown and Erusu) and one elite line IT86D-1010 were cultured in-vitro and plantlets challenged with spore inoculum of Fusarium wilt pathogen – Fusarium oxysporum f.sp. tracheiphilum in order to determine the response of the plantlets to the pathogen infestation. A solid MS medium amended with growth hormone, benzylaminopurine BAP at 1, 2, and 3 mg BAP/L was used for shoot induction. Mean disease severity score of 4.9 was recorded for Oloyin variety. There was no significant difference between the response of Ife-Brown cowpea variety and IT86D-1010 to Fusarium wilt pathogen. Least disease severity score of 2.9 was recorded for Erusu variety. Erusu was also consistently low in disease incidence and severity all through the assessment period. It was suggested that local Erusu variety be screened on the field for confirmation of this in-vitro observation.Keywords: cowpea, in-vitro regeneration, hormones, Fusarium wilt, protocolsNig J. Biotech. Vol. 25 (2013) 12-1