In vitro Selection of Kütdiken Lemon 20b to Canditate for Resistance to Phoma tracheiphila

Berna Bas and Namik Koc

Embryogenic callus of Kütdiken lemon highly sensitive to Phoma tracheiphila was successfully used for selection via in vitro tolerance to diluted toxin of Phoma tracheiphila. Twenty four callus masses were obtained after six consecutive subcultures on the medium supplemented with toxin and then these callus clusters selected were dual cultured with Phoma tracheiphila, Penicillium italicum, P. digitatum, Phytophthora citrophthora, Colletotrichum gloeosporioides, Phomopsis citri, Diplodia natalensis and Geotrichum candidum. One stable resistant callus mass was selected and labeled as Kütdiken lemon 20b. The fungal growth of Phoma tracheiphila was strongly inhibited by culture liquid of Kütdiken lemon 20b cell suspension cultures in coculture experiment comparing to sensitive Kütdiken lemon and moderate resistant Zagara Bianca. In addition, the same boiled liquid has inhibited the fungal growth. By these results, rather than any PR proteins as inhibitors to fungal development, an alternative cause for defense reaction may be secondary metabolites which are toxic to the fungus.

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