Inheritance of high duvatrienol production in tobacco
Duvane diterpene-producing tobaccos, Nicotiana tabacum L., yield a mixture of alpha- and beta-duvatrienediols (DVT-diols) and alpha- and beta-duvatrienols (DVT-ols). Recent studies suggest that these compounds are associated with resistance or susceptibility of tobacco to certain insect pests. Breeding efforts are underway to increase DVT-ol levels in tobacco cultivars for developing resistance to tobacco aphids ( Myzus nicotianae Blackman). The purpose of this study was to determine the mode of inheritance of the high-producing DVT-ol trait in tobacco. This will aid in formulating breeding strategies for altering duvane production in commercial tobaccos. The inheritance of DVT-ol production was evaluated in the low-DVT-ol X high-DVT-ol crosses TI 165 X TI 1223 and NC 60 X TI 1223. Segregation patterns indicated that high DVT-ol production behaves as a single recessive trait. Generation mean analysis, however, revealed that a digenic model for recessive epistasis more accurately describes the measured genetic effects in these two crosses. Our findings indicate that high DVT-ol production can easily be introduced into other tobacco cultivars. Genetic effects for high DVT-ol production are mainly additive and additive X additive. A significant negative correlation was observed between DVT-ol and DVT-diol production. Therefore, it would seemingly be difficult to select for both high DVT-ol and high DVT-diol production in the same plant.