The loss of expression of theH 1 gene inBt transgenic potatoes

During evaluation of potato clones and cultivars from the Cornell seed production program to confirm their resistance toGlobodera rostochiensis (Wollenweber) Behrens (golden nematode) pathotype Ro1, several cysts developed on the transgenic cultivar Atlantic NewLeaf. This transformed cultivar resulted from the insertion of aBt endotoxin gene into the golden-nematode-resistant cultivar Atlantic. In subsequent bioassay tests, golden nematode cysts developed freely on the transgenic cultivar that originated from Atlantic NewLeaf clone 6, but not on Atlantic NewLeaf clones 31 and 36. Clones 31 and 36 were from differentBt transformation events of the cultivar Atlantic that were never commercialized. RFLP analysis of Atlantic used in the transformations and the Atlantic NewLeaf clones 6, 31, and 36 showed that they possessed the marker for theH ₁ gene that confers resistance to golden nematode pathotype Rol. These data indicate that theBt transformation process adversely affected the expression of theH ₁ gene in the transgenic cultivar Atlantic NewLeaf. This finding highlights the importance of pre-release evaluation of transgenic plants for any previously known major traits such as pest and disease resistance before they are commercialized.