Suitability of small and branching sunflower varieties for molecular genetic experiments and their transformation by Agrobacterium infection

Abstract

We examined the applicability of small and branching varieties of sunflower (Helianthus annuus L. cv. Sonja, Valentine, and Pacino) for plant regeneration and gene introduction. Some small and branching sunflower varieties have advantages as transformation materials. The frequency of shoot regeneration in MS+0.1 mg l⁻¹ BA medium was high in Sonja and Valentine and many shoots formed on each explant. Roots formed easily from regenerated shoots in MS+0.1 mg l⁻¹ NAA medium and the regenerated plants grew normally and formed flowers and seeds in Pacino. In addition, the introduction of genes into branching sunflowers was shown to be straightforward. About 20–50% of regenerated shoots displayed GUS expression over wide areas of tissue in all three varieties. In Pacino, some uniformly transformed shoots were observed after simple infection with Agrobacterium. All of the steps required to obtain transformants of branching sunflowers are simple and straightforward. These small and easily transformed sunflower varieties are therefore useful subjects for molecular genetic experiments.