Rhizobium rhizogenes-mediated hairy-root transformation of daughter plants from the model strawberry Fragaria vesca's stolons.

Strawberry, a member of the Fragaria genus within the Rosaceae family, is one of the most cherished fruits worldwide. This perennial herbaceous plant also serves as a model for studying the Rosaceae family. Despite the complex polyploidy of strawberries, extensive efforts in traditional breeding over the years have resulted in improvements in yield, fruit size and shape, berry quality, and various other aspects of strawberry production. However, in addition to these conventional methods, advanced genetic technologies such as genetic modification and gene editing in intricate polyploidy varieties of strawberry are also required. Here, we present the Rhizobium rhizogenes-mediated hairy-root transformation of daughter plants from the model strawberry Fragaria vesca's stolons (also called runners), which exhibit diploid genomes. As a case study, new daughter plants were cut from the stolons, infected with R. rhizogenes harboring the mVENUS gene under Cauliflower mosaic virus 35S promoter, and then transferred on vermiculite-filled pots. After a couple of months of growth, fluorescence was observed in a few adventurous roots of the daughter plants. The hairy root transformation of daughter plants isolated from its vegetative propagation circumvents the need for seed production or callus formation and subsequent plant regeneration, which are often problematic for maintaining preferred genetic traits in complex ploidy levels. This method, which excludes genetic modification of the above-ground parts, especially the edible fruits, will open new avenues for strawberry breeding, particularly in the areas of plant nutrient absorption and fostering growth through interactions with microorganisms.