Evaluation of Nicotiana tabacum Genotypes Possessing Nicotiana africana-derived Genetic Tolerance to Potato Virus Y

摘要

New alleles influencing resistance to potato virus Y (PVY) would be valuable for developing resistant tobacco (Nicotiana tabacum L.) cultivars. The first objective of this research was to evaluate materials possessing an introgressed genomic region (Nafr) from N. africana Merx. & Buttler for their resistance against an array of nine PVY isolates. Seven near-isogenic genotypes of flue-cured tobacco cultivar K326 were produced that possessed Nafr and the recessive resistance gene, va, in different combinations and zygosities. Nafr provided little protection against mild non-necrotic isolates, but imparted significant increased resistance against the necrotic effects of two severe isolates. Data indicated that Nafr and va can be combined to increase the range and level of resistance or tolerance to PVY. A second objective was to evaluate five backcross-derived K326 Nafr/Nafr isolines and corresponding hemizygous F₁ hybrids for yield and quality characteristics in field experiments in the absence of PVY infection. The K326 Nafr/— genotypes were not significantly different from K326 for yield or cash return, and produced cured leaf with improved quality. The Nafr/Nafr genotypes were inferior to Nafr/— genotypes for yield, cash return, and cured leaf quality. Genotypes of the Nafr/— va/va combination may have the greatest practical value when yield, quality, and reaction to PVY infection are collectively taken into consideration. New alleles influencing resistance to potato virus Y (PVY) would be valuable for developing resistant tobacco (Nicotiana tabacum L.) cultivars. The first objective of this research was to evaluate materials possessing an introgressed genomic region (Nafr) from N. africana Merx. & Buttler for their resistance against an array of nine PVY isolates. Seven near-isogenic genotypes of flue-cured tobacco cultivar K326 were produced that possessed Nafr and the recessive resistance gene, va, in different combinations and zygosities. Nafr provided little protection against mild non-necrotic isolates, but imparted significant increased resistance against the necrotic effects of two severe isolates. Data indicated that Nafr and va can be combined to increase the range and level of resistance or tolerance to PVY. A second objective was to evaluate five backcross-derived K326 Nafr/Nafr isolines and corresponding hemizygous F₁ hybrids for yield and quality characteristics in field experiments in the absence of PVY infection. The K326 Nafr/— genotypes were not significantly different from K326 for yield or cash return, and produced cured leaf with improved quality. The Nafr/Nafr genotypes were inferior to Nafr/— genotypes for yield, cash return, and cured leaf quality. Genotypes of the Nafr/— va/va combination may have the greatest practical value when yield, quality, and reaction to PVY infection are collectively taken into consideration.