Pollination following grafting introduces efficiently Ocimum basilicum L. genes into Nicotiana tabacum L.

Abstract

Tobacco is an important cash crop in the world. However, the genetic basis is comparatively narrow among the modern Nicotiana tabacum cultivars, limiting its potential for quality improvement. To introduce genes conferring desirable chemical constituents from medicinal plants, a distant hybridization test was conducted between N. tabacum and Ocimum basilicum L. Seedlings of wild type Nicotiana sylvestris and N. tabacum cultivar 78-04 respectively acted as rootstock and scion. During the flowering season, hand pollination between 78-04 as pistillate parent and O. basilicum as pollen parent was carried out under 22-25°C temperature and 70-80% of relative humidity in the greenhouse. Seed sets of 55% were obtained in 78-04, and about 400 seeds per capsule were produced. But both non-grafted and self-grafted 78-04 plants rarely resulted in fruits by hand pollination and those obtained were without seed. Similar results were obtained in different material combination. The interfamilial F1 hybrids acquired showed distinct variation with various morphological characteristics, and their hybrid nature was confirmed by isozyme and random amplified polymorphic DNA (RAPD) analyses. This result indicated that pollination following grafting can facilitate gene exchange and recombination at the interfamilial level and efficiently overcome barriers of sexual incompatibility between N. tabacum and O. basilicum. Our research not only extends the genetic basis of tobacco but also will provide valuable germplasm for improvement of varieties.