N.M. Ali Bacha, A.A. Kader, H.-J. Jacobsen, F. Hassan
Fungal diseases are considered the most dangerous pests challenging apple production worldwide. Conventional breeding is a long term option to develop resistant cultivars, which, however, hardly resemble the original cultivars’ characteristics. Genetic transformation has the potential to be a useful alternative and/or complementary solution for improving fungal resistance in crops by adding only little additional genetic information and thus preserving the varietal characteristics. In the present study, the g2ps1 gene from Gerbera hybrid coding for 2-pyrone synthase which utilizes acetyl-coA and 2-malonyl-co-A for the biosynthesis of two types of 6-Methyl-4-hydroxy-2-pyrone derivatives, ‘gerberin’ and ‘parasorboside’, both contributing to fungal and insect resistance was transferred to apple.
The prime aim of the current work was to develop an efficient regeneration and transformation system for apple (Malus domestica Borkh.) ‘Golden Delicious’ and MM111 rootstock to improve their fungal resistance using genetic engineering approaches.
For transformation, the Agrobacterium strain EHA105 harbouring a pSoup-pGreenII-35S-g2ps1 vector was used to inoculate young light green leaves from sterile grown apple shoots. Putative transgenic shoots could be obtained on MS media with B5 vitamins, 4.44 µM BAP, or 9.08 µM TDZ with 1.07 µM NAA in the presence of the selection agent “PPT” at 3.0-5.0 mg L-1. Multiplication of transgenic shoots was achieved on MS medium + B5 vitamins + 4.44 µM BAP + 1.47 µM IBA, 0.58 µM GA3+1.0 g/L ME, with the selection agent PPT at 3.0-5.0 mg L-1. Putatively transgenic shoots were sub-cultured every 4 weeks. Six clones of ‘Golden Delicious’ and one clone of ‘MM111’ have been obtained and their transgenic nature was confirmed by PCR) for the presence of bar and g2ps1 genes, with transformation efficiencies of 0.4 and 0.1%, respectively.
In vitro rooting was achieved easily by transferring 2-3 cm long apical shoot segments of transgenic shoots to ½ MS rooting basal medium supplemented with 4.9 µM IBA in the presence of the selection agent ‘PPT’. Rooted transgenic plantlets were successfully acclimatized and are being kept in the greenhouse to evaluate their performance for fungal resistance under containment conditions.
Ali Bacha, N.M., Kader, A.A., Jacobsen, H.-J. and Hassan, F. (2012). PRODUCTION OF TRANSGENIC APPLE (MALUS DOMESTICA BORKH.) FOR IMPROVEMENT OF FUNGAL RESISTANCE . Acta Hortic. 961, 195-204
DOI: 10.17660/ActaHortic.2012.961.23
adventitious organogenesis, in vitro culture, genetic transformation, Agrobacterium tumefaciens, g2ps1 gene, Gerbera hybrid

Acta Horticulturae