Once the transformation protocol is fully optimized for the selected sunflower cultivars, several other steps are necessary before moving to field trials.
“The first issue is obtaining a plant from the transgenic material,” explains Dr. Götz Hensel. This can be done with techniques such as embryogenesis or more directly with organogenesis. Both methods are dependent on the genotype of the plant, and thus at Hensel’s lab, scientists are busy finding the best approach for the GAIN4CROPS’s cultivars.
A second issue comes from the fact that the sunflower, like us, is a diploid organism, and therefore it has two copies of each chromosome. The transformation step integrates the genetic change into one of them, with less predictable consequences on the phenotype. To reduce such variety and get reliable data during the field trial, we must include the change in both chromosomes and obtain a homozygotic plant for that trait. Thus, a necessary step before moving to field trials is the selfing of the transformed plants and the selection among the offspring of the homozygotic ones, exactly as described in the Mendelian rules.