Evaluation of a wide range of pepper genotypes for regeneration and transformation with an Agrobacterium tumefaciens shooter strain

A regeneration protocol developed for the Agrobacterium tumefaciens-mediated transformation of pepper (Capsicum annuum L.) was used to evaluate the potential for genetic transformation of 107 doubled haploid (DH) pepper genotypes belonging to 12 main cultivar groups. The genotypes were scored on the basis of the ratio of regenerated shoots compared to the commercial cultivar Fehérözön, which exhibited 30–70% regeneration from the total number of explants. Fifty DH genotypes responded, representing all the of the main cultivar groups, 31 of which showed regeneration frequencies similar to or better than cv. Fehérözön. By using a shooter strain with a binary vector harbouring the cucumber mosaic virus (CMV) coat protein (CP) gene and selecting regenerants on media containing kanamycin, the transformability of the pepper genotypes as well as resistance to CMV were simultaneously analyzed. The regenerated plants were selected and tested by PCR to detect the CP gene. Eighteen PCR-positive DH plants and six PCR-positive commercial Fehérözön cultivar plants were regenerated and rooted by grafting. In the case of three transgenic genotypes, presence of the CMV CP was confirmed by PCR in the T1 generation indicating the stable integration of the CP gene. In the progeny of one DH genotype of the Demre type, the presence of the transgene as well as resistance to the virus were demonstrated in the T2 generation.