Inheritance of Glandular Trichomes in Tobacco

Abstract

Trichome type and density may be responsible for genotypic differences for insect resistance and leaf chemical constituents in tobacco (Nicotiana tabacum L.). We investigated the inheritance of glandular trichomes to determine the feasibility of selecting this trait in a breeding program. Segregating generations were derived from crosses among several tobacco introductions (T.I.) and ‘Ky 14’, a burley tobacco cultivar, which differ in densities of glandular trichomes. Microscopic examinations of the abaxial surface of 20 cm long leaves were made in the field in 1982 and 1984. The F1, F2, and F3 generation means for glandular trichome density were much lower than midparent values. Additive genetic effects for trichome density were highly significant, as were the estimates of the additive ✕ additive epistatic effects. Dominance effects were significant only in the cross T.I. 1112 ✕ T.I. 1068. Heritability estimates, obtained by regression of F3 family means on F2 parental values, were 0.74, 0.77, and 0.95 for the populations derived from crosses between T.I. 1112 and T.I. 1068, T.I. 1406, and Ky 14, respectively. Chi‐square analyses of F2 data for the presence or absence of glandular trichomes indicated Ky 14 and T.I. 1406 had alleles at two loci that were different from those present in T.I. 1112, and T.I. 1068 differed from T.I. 1112 at three loci. Genes at these loci may affect glandular trichome density as well as presence or absence of glandular trichomes, but other genetic factors, including those influencing leaf size and shape, may affect trichome density.