Use of exotic Nicotiana tabacum germplasm for confronting an inverse genetic correlation in flue‐cured tobacco

Abstract

AbstractInverse genetic correlations between cured leaf yields and alkaloid accumulation in flue‐cured tobacco (Nicotiana tabacum L.) complicate the development of higher yielding cultivars while maintaining alkaloids at commercially acceptable levels. Introgression of genomic regions from exotic source material that positively affect alkaloid levels, but with less of a corresponding negative influence on yielding ability, could enhance long‐term efforts to develop improved cultivars. Germplasm accessions “TI 464” and “TI 959” were previously identified as being potentially useful for this purpose. In this study, the relationships between yield and alkaloid accumulation were investigated in BC1F1 populations derived from crosses with these materials and found to be slightly negative or slightly positive. Derived BC1F2 families were used to calculate heritability estimates for alkaloid accumulation on a single plant basis that were low to intermediate in magnitude. The relationships between alkaloid levels of leaves from individual stalk positions and alkaloid levels averaged over all stalk positions were determined. The third stalk position was found to be the most predictive of average alkaloid levels. Selection for alkaloid levels using a single leaf from this stalk position could increase breeding efficiency. BC4F6 lines carrying low genomic contributions from either TI 464 or TI 959 were generated and evaluated as lines per se and in F1 hybrid combinations with a very high‐yielding inbred line with increased leaf number. Performance of these materials indicated that TI 464 and, to a lesser extent TI 959, may be useful for developing higher yielding tobacco cultivars with acceptable alkaloid levels.