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Title: INCREASED RESISTANCE TO ERWINIA AMYLOVORA EXHIBITED BY TRANSGENIC 'ROYAL GALA' APPLE (MALUS X DOMESTICA BORKH.) SHOOTS, CARRYING A MODIFIED CECROPIN MB39 GENE

Author
item LIU, Q - ARS CONTRACT EMPLOYEE
item INGERSOLL, J - ARS POSTDOC
item OWENS, L - ARS RETIRED COLLABORATOR
item Salih, Sarbagh
item MENG, R - ARS, CORVALLIS, OR
item Hammerschlag, Freddi

Submitted to: Acta Horticulture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/3/2000
Publication Date: 12/20/2001
Citation: Liu, Q., Ingersoll, J., Owens, L., Salih, S.S., Meng, R., Hammerschlag, F.A. 2001. Increased resistance to erwinia amylovora exhibited by transgenic 'royal gala' apple (malus x domestica borkh.) shoots, carrying a dified cecropin mb39 gene. Acta Horticulture Proceedings. 560:95-99

Interpretive Summary: Fire blight, caused by the bacterium Erwinia amylovora, is a serious and difficult to control disease of many important apple cultivars, and economic losses in commercial orchards can be significant, and sometimes devastating. Improvement of apple via conventional breeding is a slow, lengthy process due to its long juvenile period, high level of self incompatibility and the highly heterozygous nature of the genome. Although gene transfer techniques make it possible to overcome these problems by direct transfer of useful genes (e.g. for disease resistance) into commercially important cultivars, very few transgenic apple trees have been produced. Recently, genes encoding lytic proteins, attacin E and T4 lysozyme were successfully transferred to apple cultivar Galaxy and several transgenic lines expressed increased resistance to fire blight. In this study we report on the transformation of 'Royal Gala' apple (highly susceptible to fire blight) with the gene for cecropin M39 and the response of the transgenic shoots to Erwinia amylovora. This research should be of use to scientists interested in using gene transfer techniques to introduce genes for disease resistance into apple and other species susceptible to bacterial diseases.

Technical Abstract: Transgenic 'Royal Gala' apple (Malus x domestica Borkh.) shoots were obtained by Agrobacterium-mediated gene transfer using a vector with T DNA encoding a modified cecropin gene MB39 joined to a secretory coding sequence from barley alpha amylase, and placed under the control of a wound-inducible tobacco osmotin promoter. The integration of the cecropin MB39 gene into apple was confirmed by Southern blot analysis. The transformation efficiency was 1.5 percent when internodes from etiolated shoots were used as explants and 2 percent when leaf explants were used. Three of the seven transgenics were significantly more resistant to Erwinia amylovora than the non transformed 'Royal Gala' control. This research demonstrates the potential of introducing the cecropin gene to generate plants with increased levels of disease resistance.