Transgenic strawberry plants expressing a thaumatin II gene demonstrate enhanced resistance to Botrytis cinerea

A thaumatin II cDNA (thau II) driven by the CaMV 35S promoter was introduced into strawberry (Fragaria × ananassa) via Agrobacterium-mediated transformation. Following transformation, 19 regenerated plant lines were obtained, of which, 14 were found to possess thau II and neomycin phosphotransferase (npt II) genes, while five plants possessed only the npt II gene. In 11 transformants, protein bands that reacted with a thaumatin II antibody were observed, while 3 plants had no detectable thaumatin II. Three transgenic lines accumulating the highest levels of thaumatin II protein and three control plants with npt II and uidA genes or only the npt II gene and non-transgenic plants cv. Firework were tested for resistance against gray mold (Botrytis cinerea) by infection with a conidial suspension. All transgenic lines tested expressing the thaumatin II protein showed a significantly higher level of resistance compared to the control plants, as measured by necrotic lesions and sporulation of the pathogen.