Evaluation Of Tobacco Lines And Hybrids Carrying Beinhart-1000 Alleles At The Phn15.1 Locus For Agronomic And Disease Resistance Characteristics

Introgression of novel components of partial resistance to P. nicotianae can be used to increase the range, level, and durability of resistance to the black shank disease of tobacco. Here we describe the development and evaluation of BC9F3 sub-sub-NILs of elite flue-cured tobacco cultivar 'K326' carrying a favorable allele(s) for resistance at the Phn15.1 quantitative trait locus derived from cigar cultivar 'Beinhart 1000.' We were able to identify a series of genotypes with significantly improved black shank resistance relative to K326 and, importantly, that possessed a mutant allele of NtCPS2, a closely linked gene involved in the biosynthesis of Z-abienol (an undesirable flavor and aroma compound for flue-cured tobacco). Some evidence of a potential influence of Phn15.1 on resistance to bacterial wilt caused by Ralstonia solanacearum was also observed. The Beinhart 1000 allele(s) at Phn15.1 acted in an additive manner to affect resistance to black shank. No significant reductions in cured leaf yields were found to be associated with Phn15.1-mediated black shank resistance. Although not statistically significant, trends of slightly reduced physical cured leaf quality were observed as the zygosity of the Beinhart 1000 Phn15.1 allele(s) increased. Increases in percent total alkaloids and reductions in percent reducing sugars were also found as the zygosity at Phn15.1 increased. These changes probably did not result in cured leaf chemistry being outside of the bounds of commercial acceptability, however. The derived genetic materials enhanced for partial genetic resistance to black shank should be of value for future flue-cured tobacco cultivar development efforts.