QTL analysis of alkaloids in tobacco (Nicotiana tabacum L.)

Abstract:
Alkaloids are important chemical components of tobacco. In order to identify the genetic structure of alkaloids in tobacco and explore the major loci controlling related traits, the QTL for tobacco alkaloids was performed in this study. A total of 271 recombinant inbred lines (RILs) were constructed with Y3 and K326 as parents. The RIL population was planted in Yanhe, Yuxi, Yunnan Province and Shilin, Kunming, Yunnan Province in 2020, 2021 and 2022, respectively. Five alkaloid traits, including total plant alkali (TPA), nicotine (NIC), nornicotine (NOR), anabasine (ANAB) and anatabine (ANAT) were measured. A linkage map with 46129 markers was constructed by genome sequencing of the population. QTL mapping was performed with the software QTLNetwork 2.0, which was developed based on a mixed linear model. A total of 15 QTLs were identified with significant additive effects, among which 4 major QTLs explained more than 10% of the phenotypic variation in the corresponding traits. A total of 6 QTLs contributing to significant environmental interaction effects were detected, and 6 pairs of QTLs with significant additive-by-additive epistasis effects and/or epistasis-by-environment interactions were detected. The results lay the foundation for further isolation of candidate genes, analysis of genetic mechanisms and promotion of molecular improvement of tobacco alkaloid traits.