Transformation of Japanese persimmon (Diospyros kaki Thunb.) with a bacterial gene for choline oxidase

This report describes the first successful genetic engineering of tolerance to salt in an agriculturally important species of woody plants by Agrobact erium-mediated transformation with the codA gene of Arthrobacter globiformi s. This gene encodes choline oxidase, which catalyzes the oxidation of chol ine to glycinebetaine. The binary plasmid vector pGC95.091, containing a ka namycin-resistance gene (nptII), a gene for beta -glucuronidase (gusA) and the codA gene in its T-DNA region, was used with a disarmed strain of Agrob acterium tumefaciens, EHA101, to transform Japanese persimmon (Diospyros ka ki Thunb. 'Jiro') by the leaf disk transformation method. The pRS95.101 pla smid that included only nptII and gusA in the T-DNA region was used as a co ntrol. We selected eight transgenic lines with one or two copies of the T-D NA after transformation with pGC95.091 (PC lines) and three lines after tra nsformation with pRS95.101 (PR lines). The eight PC lines produced choline oxidase and glycinebetaine whereas neither was found in untransformed 'Jiro ' and in the control PR lines. Transgenic plants grew normally, resembling wild-type plants both in vitro and ex vitro. The activity of photosystem II in leaves of the transgenic Japanese persimmon plants under NaCl stress wa s determined in terms of the ratio of the variable (F-v) to the maximum (F- m) fluorescence of chlorophyll (F-v/F-m). The rate of decline in (F-v/F-m u nder NaCl stress was lower in the PC lines than in the control PR lines. Th ese results demonstrated that genetic engineering of Japanese persimmon, wh ich allowed it to accumulate glycinebetaine, enhanced the tolerance to salt stress of this plant.