Consequences of gene stacking by hybridization in transgenic plants

Abstract

The hybridization method, also used for stacking multiple transgenes, has been performed by the plant breeders since the beginning of the genetic improvement of the cultivated species. In spite of the absence of evidence of effects caused by the gene stacking by hybridization in transgenic plants, additional studies have been required by the Regulatory Agencies as a condition for the approval of the stacked product. The objective of this work is to demonstrate, through the comparison of the nutritional composition, the phenotypic traits and the expression of the transgenic proteins CRY1F, CRY34AB1, CRY35AB1 and PAT, that the plant carrying multiple transgenes stacked by hybridization is equivalent to the isogenic hybrid and to the parents carrying the single events. In this work, in order to demonstrate the nutritional and phenotypic equivalence, the stacked corn TC1507 × DAS-59122-7 was compared with the isogenic hybrid. Grains and forage were tested for nutritional composition (protein, carbohydrates, ash, fiber, minerals, amino acids, fatty acids, vitamins and antinutrients). The plants were compared for their phenotypic traits (vigor, time of flowering, plant height, ear height, lodging and productivity). The expression of the transgenic proteins (CRY1F, CRY34AB1, CRY35AB1 and PAT) by the stacked product was compared with the expression by the plants carrying the single events TC1507 and DAS-59122-7. The conclusion of this work is that the plant carrying the stacked transgenes is equivalent to the plants carrying the single events, confirming the absence of any effect caused by stacking genes through hybridization in transgenic plants.