Study On High Potassium Flue-cured Tobacco Breeding And Application

Potassium content is one of the most important limiting factors that affect the quality of flue-cured tobacco. In order to increase potassium content in flue-cured tobacco, the genotype with high efficiency of potassium have successfully obtained by the introduction of exogenous DNA to K326(CK) using pollen tube pathway, which indicate hybridization obstacles resolved and transfer of genetic information realized between different distant species. In addition,3transgenic lines with high potassium genotypes indentified to study statistic of agronomic characters, efficiency of potassium absorption, ecological adaptability, potassium responsiveness and economic trait. Meanwhile, hybridized combination MYK5with better comprehensive properties were obtained to identify5hybridized combinations based on the3transgenic lines as male parent. The main results obtained are as follows:1. This study proved that pollen tube pathway can provide an approach to exogenous DNA introduction to flue-cured tobacco K326to increase potassium content. Besides, this technique can remove the impediment for interspecific hybridization and realize the transfer of genetic information from distant species, providing a platform for modification of flue-cured tobacco and germplasm innovation.2. It was the first time that the way was found to test the introduction of potassium with high efficiency genotype. Through testing the expression level of related gene of nutrition content in12potassium lines and analysis of potassium content in flue-cured tobacco, it was found that in5strains with high potassium content, the expression level of gene TORR1and NtTPR1are higher than others. Besides, gene CIPR23is also high in expression level. The quality of strain with high efficient genotype can be predicted based on these gene expression levels.3. Using pot culture, the study on phenotypic differences and nutrition characteristics of potassium with high efficient genotype K2, K3,K5,K7,K9and K326(CK) of potassium in flue-cured tobacco were presented as follow:The absorbing power of flue-cured tobacco with high potassium content genotype is higher compared with control at different potassium supply level; Compared with control, high-K genotypes had stronger resistances, much better potassium absorption and accumulation under potassium stress. Through a comprehensive evaluation on multiple indexes, including, root absorption capacity, traits of potassium absorption and accumulation, dynamical parameters of root absorption and disease resistance etc, K5were considered as quite desirable objectives for breeding high-K genotypes in this study4. Experiments on different tobacco varieties at adaptability to different ecological zones, sensibility to different fertilizers and ripening property showed that the production and output value all reached strong growth condition at early stage. Among the3new stains, K5ranked the first when evaluating the economic character, K2the second, K7the last. Potassium efficiency was the most outstanding one among all the chemical components in tobacco.5. Using K2, K5and K7as male parent to produce5hybridized combinations, it was experimented to improve agronomic traits of high potassium flue-cured tobacco and resistance of black shank disease. Results showed that, though genetic factor is important for resistance, it is not the decisive one. Proper hybridized combination can effectively improve the resistance of high potassium flue-tobacco. Additionally, genetic factor has a huge impact on potassium content of tobacco leaves and in these5hybridized combinations, all parts of tobacco leaves contain more potassium than the control does. Among these5combinations, MYK5enjoys the most apparent heterosis with heredity of characteristics of high potassium from parent of potassium with high efficient genotype, and it is a good breeding object for high potassium flue-cured tobacco.Through a comprehensive evaluation on multiple indexes, including expression level of related gene, potassium content, agronomic characters, output value, disease-resistance and stress-resistance, MYK5was considered the best with high potassium strain K5as its male parent, which has been put into Hunan Flue-cured Varity Test, and recommended to join2014Provincial Unified Regional Test. Therefore, MYK5is expected to be developed into new tobacco varieties with potassium efficient features.