A. Schwekendiek, C. Horlemann, O. Spring, M. Stanke, M. Höhnle, G. Weber
Fungal pathogens like Downy Mildew (Pseudoperonospora humuli [Miy. et Tak., Wilson]) or Powdery Mildew ((Podosphaera macularis formerly called Sphaerotheca humuli) cause serious diseases in hop cultivation in Europe and North America. In hop, breeding for resistance to these diseases has proven difficult and time consuming. Furthermore, breeding of hop for disease resistance is not suitable because the quality characteristics of a specific hop variety must be maintained for brewer acceptance. Alternatively, resistance against fungi was introduced successfully into plants by genetic transformation. Expression of genes such as stilbene synthase in transgenic plants has increased resistance against fungal pathogens in other plant species. An efficient procedure for genetic transformation of hop (Humulus lupulus L.) mediated by Agrobacterium tumefaciens and subsequent regeneration of transgenic plants was recently established in our laboratory. We report here on the transformation of hop aimed at increasing resistance against pathogens. Shoot internodes from in vitro cultures of explants of hop (cv. Tettnanger) were transformed with a gene construct harbouring stilbene synthase. Approximately 6 months passed between transforming explants and growing plants in the greenhouse. The presence of the transgene in plants growing in the greenhouse as well as the absence of contaminating A. tumefaciens was verified by multiplex PCR (polymerase chain reaction). Furthermore, genomic DNA from different transgenic plants was purified. In each sample, the presence of a complete gene of stilbene synthase was verified by DNA sequence analysis. These transgenic plants have been planted outside in a screenhouse for cultivation under farm conditions. Tests for evaluating the expression of stilbene synthase and measuring resveratrol accumulation in transgenic plants as well as their resistance against fungal pathogens are being performed.
Schwekendiek, A., Horlemann, C., Spring, O., Stanke, M., Höhnle, M. and Weber, G. (2005). HOP (HUMULUS LUPULUS L.) TRANSFORMATION WITH STILBENE SYNTHASE FOR INCREASING RESISTANCE AGAINST FUNGAL PATHOGENS. Acta Hortic. 668, 101-108
DOI: 10.17660/ActaHortic.2005.668.13
Transgenic plant, Agrobacterium tumefaciens, Downy Mildew, pathogenic fungi, resveratrol, secondary metabolism, HPLC

Acta Horticulturae