Development of anther-derived flue-cured tobacco dihaploids from PVY resistant DH10 hybrid

1.Introduetion Potare virus Y (PVY) is an increasing problem affecting Croatian tobacco growers (BUZANCIC, 1988). It causes sig­ nificant economic losses not only on tobacco, but on all solanaceous crops. Therefore, a breeding program has been initiated to produce a flue-cured tobacco (Nicotiana tabacum L.) cultivar resistant to PVY, with better yield and quality than standard cultivars grown inCroatia: Drava and DH10. The source breeding material with genetic variabi­ lity for resistance to PVY, yield and cured leaf quality was formed by hybridization ofthe Croatian line GV3 and the cv.Virginia D. The hybrid is known as the commercial cul­ tivar DH10, which has a genetic basis for the traits ofinter­ est in this study. The parental line GV3 is resistant to blue mold caused by Peronospora tabacinaAdam(GORNIKet al., 1973) and to PVY (SMALCELJ, 1992), but it is characterised by Iow quality (SMALCELJ, 1988). The German variety Vir­ ginia D is also described as resistant to PVY, but it is extremely susceptible to blue mold and black root rot caused by Thielaviopsis basicola Berk. and Br. Ferraris (PUL­ ULU, 1985). In cornparative trials on the field ofthe Tobac­ co Institute Zagreb in Pitomaca, VirginiaD had a smaller growth and lower yield than the standard cultivar Drava, but it reached a higher price ($/kg) (SMALCELJ, 1990). The hybrid, DHI0, displays an acceptable level of resis­ tance to PVY and blue mold, and in the Croatian growing area its yield is approximately 2 t/ha, which is better than the yield of the parentalline GV3 and the cv. Virginia D. Indeed, tobacco producers have found this cultivar more acceptable than Drava since flue-curing of the leaf is rela­ tively simple to achieve (KOZUMPLIK etal., 1992).