TRANSGENIC APPLE PLANTS EXPRESSING CHITINASES FROM TRICHODERMA HAVE INCREASED RESISTANCE TO SCAB (Venturia inaequalis)

Transgenic ‘Marshall McIntosh’ apple plants expressing an endochitinase (Ech42) and an exochitinase [N-acetyl-b-D-glucosaminidase (Nag1)] of Trichoderma harzianum were selected by Agrobacterium-mediated transformation and characterized.
There was a significant positive correlation between resistance of the transgenics to scab and the level of expression of either chitinase, although the levels of resistance observed in exochitinase-transgenic lines were less than in endochitinase-transgenic lines. Endochitinase expression reduced plant growth, while exochitinase expression had no effect on plant growth.
When both enzymes were expressed in planta they acted synergistically to reduce disease.
Transgenic ‘McIntosh’ lines were identified with a low level of endochitinase expression and a high level of exochitinase expression that were resistant to scab and had negligible reduction in growth in a greenhouse trial.
These transgenic apple lines are now being grown in the field for evaluation of scab resistance, tree performance, and fruit quality and yield.

Eucarpia symposium on Fruit Breeding and Genetics

J.P. Norelli, J.P. Bolar, G.E. Harman, H.S. Aldwinckle

Endochitinase, Ech42, N-acetyl-b-D-glucosaminidase, Nag1, genetic engineering, ‘Marshall McIntosh’.

https://doi.org/10.17660/ActaHortic.2000.538.108