Inheritance and QTL Analysis of Holding Curing Potential in Flue-Cured Tobacco
|School||Chinese Academy of Agricultural Sciences|
|Keywords||Flue-cured Tobacco Holding Curing Potential Genetic Analysis Genetic Map QTL|
Flue-cured tobacco is the main raw material of the cigarette industry, and it has the largest growingarea and yields worldwide. The quality of flue-cured tobacco is mainly determined by three uspects,varieties, cultivation conditions and curing. Curing is the last link of quality control in tobaccoproduction. Curing characteristics is an important aspect of the quality of tobacco and formulated curingprocess has become a key step for tobacco curing according to the curing characteristics of flue-curedtobacco varieties. As an important part of the curing characteristics, holding curing potential refers tothe tolerance against the curing environment during yellowing and color fixative, and can measure thedegree of difficulty about color fixative. This study aimed to figure out the inheritance of holding curingpotential of flue-cured tobacco with the mixed major-gene plus polygene inheritance model,construction of genetic linkage map with SSR molecular markers and QTL mapping technology, whichmay provide an important reference for breeding the holding curing potential varieties, molecularassisted selection and cloning of genes related to holding curing potential. The main results are asfollows:（1） The quantifying standard was formulated by observing and calculating the browning indexes（BI=∑B/n） via experiments under dark condition. The holding curing potential of6generations （P1, P2,P1, P2, B1and B2） derived from two crosses （Yunyan85×Dabaijin599and Zhongyan100×Cuibi1） weregenetically analyzed with the mixed major-gene plus polygene inheritance model. The holding curingpotential of flue-cured tobacco was largely controlled by two major genes havingadditive-dominance-epistatic effect along with polygene having additive-dominance-epistatic effects（Model E-0）.（2）200selfed P2and126P2:3individuals derived from the cross between Yunyan85, which isexcellent in holding curing potential, and Dabaijin599, which is low-quality in holding curing potential,were used as materials. Using Mapmaker/EXP3.0software, a genetic map was built by SSR （SimpleSequence Repeat） markers. Totally,4710primer pairs were used for polymorphism screen, of which237polymorphic pairs were selected for map construction. According to the results,204markers werelocated evenly on24linkage groups, and the total distance is2318.2cM.（3） QTL analysis was performed by inclusive composite interval mapping （ICIM） for P2and P2:3phenotypic values. Five QTLs were detected in the P2population, which were distributed on c3, c9andc17linkage groups, and their contributions to phenotypic variance were from6.39%to47.01%.qHCP-3-1and qHCP-9were main locus. Through QTL analysis of P2population derived from Yunyan85×Dabaijin599, two major QTLs and3minor QTLs were detected, which were consistent with theresults of ‘genetic effects of holding curing potential’ study （controlled by2pairs of major genes+multi genes）. For the5QTLs detected in P2:3population, they were distributed on c2, c3, c12, c20linkage groups with contributions to phenotypic variance from9.29%to34.78%. qHCP-2-1、qHCP-2-2、qHCP-3and qHCP-12,qHCP-3-1and qHCP-9were main locus. These results laid foundation for QTL fine mapping and molecular-assisted breeding by constructing permanentpopulation.