ANALYSIS OF GENE EXPRESSION STABILITY IN TRANSGENIC APPLE PLANTS AND APPLE FRUIT

Independently transformed Malus domestica ‘Elstar’ and ‘Holsteiner Cox’ lines, each harbouring different copy numbers of the stilbene synthase gene from grapevine (Vitis vinifera L.) and the bar gene from Streptomyces hygroscopicus, were used to assess transgene expression stability in apple plants and their fruit.
The stilbene synthase is responsible for the synthesis of the phytoalexin resveratrol in grapevine and was introduced to improve fungal resistance.
The bar gene confers resistance against the herbicide glufosinate ammonium and was cotransferred as a selectable marker.
The investigation included analysis of leaf material from long-term in vitro cultures, from plants growing on their own roots as well as grafted on a rootstock for three years under greenhouse conditions, and from young and mature transgenic apple fruit.
RT-PCR analysis for detecting specific mRNAs, HPLC for proving resveratrol synthesis and leaf paint assays with glufosinate ammonium to examine herbicide detoxification revealed stable expression of the transgenes in all lines except one 3.5 years after the initial transformations.
Preliminary results using fruit material revealed that the genes are also active in apple fruit tissue.

XI Eucarpia Symposium on Fruit Breeding and Genetics

K. Briviba, K. Lein, I. Szankowski

Malus x domestica, transformation, stilbene synthase, herbicide resistance, resveratrol

https://doi.org/10.17660/ActaHortic.2004.663.79