AGROBACTERIUM-MEDIATED TRANSFORMATION OF THE CULTIVATED STRAWBERRY (FRAGARIA X ANANNASSA DUCH) USING DISARMED BINARY VECTORS

Two disarmed Ti-binary vectors in Agrobacterium tumefaciens have been used to produce viable transgenic strawberry plants. Fertile strawberry plants with a normal phenotype were regenerated after transformation with pBIN6, which carries genes for nopaline synthase (nos) and neomycin phosphotransferase (nptII) (conferring kanamycin resistance). The transfer and expression of the two genes was confirmed by Southern blot analysis, the detection of nopaline synthase (NOS) activity in vegetative and reproductive tissues and rooting in vitro in the presence of kanamycin. The nos gene continued to be expressed in glasshouse-grown plants many months after removal from in vitro growth conditions. After selfing the RO plants nos segregated in the R1 progeny according to a 3:1 Mendelian ratio. In in vitro germinated seedlings there was complete correlation between the presence of nopaline synthase activity and the ability of leaf segments to produce callus on a medium containing kanamycin. Transgenic clones that exhibited an abnormal phenotype associated with cytokinin overproduction were produced when plants were transformed with pSS1, a derivatives of pBIN19 carrying both the nptII gene and the ipt gene (encoding the enzyme isopentenyltransferase). Shoots of these clones grew on hormone-free medium, could not be induced to root and their growth was unaffected by the presence of 50 μg/ml kanamycin in hormone-free media. © 1990.