Abstract
Among many specific hybrids in Nicotiana, we observed 11 tumorous ones; F1 N. glauca×N. langsdorffii, F1 N. glauca×N. longiflora, F1 N. glauca×N. plumbaginifolia, F1 N. paniculata×N. langsdorffii, F1 N. rustica×N. cavanillesii, F1 N. suaveolens×N. langsdorffii, F1 N. suaveolens×N. plumbaginifolia, F1 N. suaveolens×N. longiflora, F1 N. gossei×N. alata, F1 N. gossei×N. longiflora and F1 4x N. tabacum×N. alata. Among them, 3 hybrids were newly found by us, namely, F1 N. gossei×N. alata, F1 N. gossei×N. longiflora and F1 N. suaveolens×N. plumbaginifolia.
The tumor shapes ranged from teratoma-type to massive-type. In F1 N. glauca×N. langsdorffii, the spontaneous stem tumors to grow at the end of flowering. The locations of the spontaneous tumors were, a) cicatriculae of flowers and leaves, b) lateral buds of dropped flowers and leaves, c) apexes of lateral shoots, d) internodes and e) various parts of roots.
Injury of leaf veins and stems of F1 N. glauca×N. langsdorffii is assumed to stimulate tumors formation. Pricking experiments showed that tumors were more frequently induced in the upper part of the stem than in the lower one.
