The Breeding Of Novel Tobacco Germplasm By Distant Hybridization Between Tobacco And Medicinal Plants

How to reduce the harmful effects of smoking on human health is one of the most important issues for tobacco industry. Breeding of novel tobacco germplasm with less or no toxicity is an effective and economical strategy. Medicinal plants contain a lot of medicinal ingredients which are greatly applied in the therapy and protection of human diseases. Developing novel tobacco germplasm with medical value by wide crossing tobacco and medicinal plants is a new approach although it is challenging. Based our previous studies, this current investigation is to breed novel tobacco germplam with medical value by distant hybridization between tobacco (Nicotiana tabacum L.) and medicinal plants such as Coimum bailicm L , Montha haplacaly brig and Tolinum paniolatume (jaog) coorin . We developed an optimal strategy for tobacco distant hybridization and three new hybrid lines of tobacco with medicinal value, which were approved by a series of analysis such as offspring variants and their genetics, chemical components in leaves and cigarette gas, toxicity test using mice. The main results are described as followings.The optimal technology for tobacco distant hybridization included using the grafted tobacco plants as female, repeated pollination by pollen from medicinal plants and establishing an environmental condition with lower temperature and higher moisture for crossing. Combined use of these techniques could effectively overcome hybridization incompatibility. The hybrid progenies were backcrossed with tobacco as a recurrent parent, which could greatly improve the hybrid sterility.Phenorype analysis indicated that the hybrid generated a lot of different variants. The genetically stable hybrid lines exhibited a higher similarity with tobacco plants in the main agronomic traits while they also showed the characteristics of medicinal plants in the traits such as leaf color and shape, axillary bud growth and resistance.Chemical analysis of the leaf and cigarette gas displayed that the genetically stable hybrid lines contained the medicinal components which exit in the medicinal plants used as male parents, but not in the tobacco plants used as female parents. Compared with the commercial tobacco varieties, these new hybrid lines have a middle or less nicotine and lower level of total sugar in their leaves. In addition, these hybrid lines could generate the special aroma which were not produced by the known tobacco products. The toxicity test using mouse as model proved these hybrid lines had a less toxicity than the commercial tobacco.The data of esterase isoenzyme and DNA printings revealed that these stable hybrid lines integrated some loci derived from the medicinal plant genomes and had a new characteristic of gene expression. In conclusion, these genetically stable hybrid lines bred by distant hybridization between tobacco and medicinal plants have some new characteristics such asless toxicity, special aroma and medicinal ingredients which are not exited in the known tobacco germplasm resources. Therefore, they are new types of tobacco germplasm with potential in tobacco breeding and industry.