S01 - Session O1 - Field investigation of consequences from the genetic modification resulting in the fire blight resistant cisgenic apple line

Authors: Ina Schlathölter, Giovanni A.L. Broggini, Bruno Studer, Michael Meissle, Jörg Romeis? Andrea Patocchi *

Apple cultivars resistant to diseases and pests can reduce the currently high chemical footprint of apple production. However, development of such cultivars by classical breeding is a challenging and lengthy process. The cisgenic approach can be used to amend a susceptible apple cultivar with apple-own resistance genes by means of genetic engineering. The cisgenic line C44.4.146 was generated by transferring the fire blight resistance gene FB_MR5 from Malus x robusta 5 to the susceptible cultivar 'Gala Galaxy'. To assess whether unintended effects occurred during the generation of the line, a field trial was conducted over five years with trees of the cisgenic line C44.4.146 and multiple control cultivars. A total of 44 tree- and fruit-related traits were assessed and compared over several years in the field. No traits of C44.4146 showed statistically significant differences from its wild-type, nor were they outside the variation observed among the 'Gala' controls over all observation years. The fruit flesh and peel metabolome were also investigated for two consecutive years. No C44.4.146 metabolites were consistently identified as differentially abundant in both years and outside the variation observed among the controls. Finally, the effect of a diet amended with leaf-powder of the different genotypes included in the field trial on the fitness of the arthropod decomposer species Drosophila melanogaster and Folsomia candida was investigated. The leaf material of C44.4.146 did not adversely affect survival, growth or fecundity of the two arthropods. Despite the fact that only a single cisgenic line was investigated and that FB_MR5 resistance is of limited durability, the results show that cisgenesis represent a valid complementary approach to conventional breeding to develop high quality resistant cultivars.