DIFFICULTIES IN THE ESTABLISHMENT OF AXENIC IN VITRO CULTURES OF FIELD COLLECTED COFFEE AND CACAO GERMPLASM

Orthotropic shoots of both species were collected each month over a two years period in Cameroon. They were rapidly shipped to the laboratory in Belgium for disinfection and inoculation onto culture media. Bacterial and fungal contamination were respectively associated with nodal and meristem cultures of coffee and with nodal cultures of cocoa. A wide range of sterilants used at various concentrations, alone or in combination and several antibiotics and fungicides as medium additives were tested without success.

Moreover, some antibiotics previously considered non-phytotoxic induced explant necrosis. Other attempts to control the severe contaminations by pretreatment in Cameroon of explants with surface sterilants and by inoculation on media containing antimicrobial agents before shipping failed.

Partial control of contamination was eventually achieved by pretreatment of clonal material grown in a greenhouse. This last procedure allowed the clonal micropropagation program to start.

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