Addition of Blue Mold Resistance to KTTII Burley Tobacco Varieties

Although the initial objective of the Kentucky-Tennessee Tobacco Improvement Initiative (KTTII) was the development of disease resistant varieties, more recently the focus has been on harm reduction in burley tobacco. The primary research objective of KTTII for the last five years has been the transfer of three mutant alleles (now referred to as “Zyvert Technology”) into commercial burley tobacco varieties developed by KTTII. Because these mutant alleles reduce the conversion of nicotine to nornicotine, thereby minimizing formation of nitroso-nornicotine which is thought to be a carcinogen, this has been a high priority within the tobacco industry. The introgression of these three alleles into parental lines of existing KTTII varieties has been an exhaustive and expensive undertaking, leaving few resources for the continued development of new disease resistant varieties. However, this project is nearing completion. KT 209Z, KT 210Z, KT 212Z, and ms TN 86Z were released as commercial varieties in March, 2015. KT 204Z, KT 206Z, and ms TN 90Z were entered in the Regional Quality Trial (RQT) in 2015. If these three varieties meet RQT minimum standards, they will be released in March of 2016. At that point, the lone variety under development will be ms KY 14 X L8Z, which has a projected release date of 2018. The actual target date for anticipated commercial production of these Zyvert varieties is still undetermined. To move the desired blue mold resistance trait into the male sterile version of FT 2002Z required for commercial hybrid seed production, pollen from the backcross four generation of FT TKF 2002Z will be used to pollinate FT TKS 2002Z. This will be followed by an additional backcross with BC5 pollen of FT TKF 2002Z. To eliminate the early flowering FT trait from the final blue mold resistant parental lines, in the BC5S1 generations of both TKF 2002Z and TKS 2002Z, seed will be collected only from plants that exhibit normal flowering characteristics and that are verified via marker analyses to be homozygous for the desired Zyvert and blue mold resistance alleles.