Agronomic Performance of Tobacco Mosaic Virus-Resistant Tobacco Lines and Hybrids Possessing the Resistance Gene N Introgressed on Different Chromosomes
- Ramsey S. Lewis * and
- Cara Rose
Resistance to tobacco mosaic virus (TMV) is conferred by the single dominant gene, N, in Nicotiana glutinosa L. This gene has been transferred to cultivated tobacco (N. tabacum L.) via interspecific hybridization and backcrossing. Current TMV-resistant (TMVR) cultivars carry N introgressed on chromosome H of the N. tabacum genome. Undesirable linkage drag effects have caused associations with reduced yields and/or quality in flue-cured tobacco, however. Other germplasm lines possess the gene transferred onto an alternative chromosome. The objective of this research was to compare the agronomic performance of nearly isogenic lines (NILs) and hybrids possessing N on different chromosomes and originating from four N donor lines. Regardless of the source of the gene, Nn heterozygotes were intermediate in value for yield, cash return, and cured leaf chemistry relative to nn and NN homozygotes. Lines and hybrids carrying N transferred from Xanthi nc produced the highest yields, whereas those possessing N introduced from TI 1473 exhibited the lowest yields. Overall, materials possessing N on chromosome H were not found to be significantly different for yield, grade index, value per hundred weight (US$ cwt−1), or cash return from those carrying the resistance gene on the alternative chromosome. Breeding strategies designed to reduce the amount of N. glutinosa chromatin linked to N are needed to develop TMVR flue-cured tobacco cultivars that do not exhibit an accompanying yield penalty.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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