白肋烟分子标记遗传图谱的构建及部分性状的遗传剖析

用112个AFLP、6个SRAP标记构建了白肋烟的分子标记遗传连锁图谱，包括22个连锁群(A1~A22)，总遗传长度为1 953.6 cM，标记的平均间距为20.5 cM，有25个标记表现偏分离(17.0%)，主要集中在第1、11和14连锁群上；利用Windows QTL Cartographer Ver. 2.5软件进行QTL分析，结果表明，共检测到11个主效QTL，其中7个与化学成分性状相关，另外4个与农艺性状相关。与烟碱、总氮和总糖相关的QTL各2个(btnic1和btnic2)、2个(bttn1和bttn2)和3个(btts1、btts2和btts3)，与株高(btph)、茎围(btls)、节距(btpt)和中部叶长(btl)相关的QTL各1个，没有检测到与总钾、总叶数和中部叶宽相关的QTL，其中与烟碱和总氮相关的QTL处于共分离状态(分别为btnic1和bttn1)，表明烟叶烟碱合成与氮素代谢之间可能存在某种未知的生物学相关性，11个主效QTL对各性状表型变异的贡献率在12.3%~26.4%之间。

Construction of Genetic Linkage Map of Burley Tobacco (Nicotiana tabacum L.) and Genetic Dissection of Partial Traits

The agronomic traits and chemical components are very important factors affecting yield and tobacco leaf quality. Dissecting genetic control of these traits can facilitate the breeding of new tobacco cultivars by marker-assisted selection (MAS). The objective of this study was to identify QTLs controlling partial agronomic traits and chemical components in burley tobacco. A double haploid (DH) population of burley tobacco was used to construct a molecular marker genetic linkage map. The DH population was derived from a cross between high quality cultivar Burley37 with high nicotine content and Burley21 with low nicotine content. The mapping population was planted in main production region of burley tobacco in Hubei province for two years to obtain repetitive phenotype data. On the basis of this map, QTLs for four chemical components including nicotine (NIC), total nitrogen (TN), total sugar (TS), total potassium(TK) of air-cured central tobacco leaf and six agronomic traits including plant height (PH), stalk circumference (LS), distance between nodes (PT), number of total leaf (LN), length of central leaf (L) and width of central leaf (W) were analyzed by using software Windows QTL Cartographer Ver. 2.5. The results showed that a total of 112 AFLP loci and six SRAP loci assembled into 22 linkage groups (A1–A22) composed the whole linkage map spanning 1 953.6 cM with an average distance of 20.5 cM between adjacent loci. There were 25 distortion-segregation loci (17.0%) mainly clustering in linkage groups A1, A11, and A14. A total of eleven main QTLs including seven QTLs influencing chemical components and the other remaining four QTLs conferring agronomic traits were detected. Out of them, two (btnic1 and btnic2) QTLs were detected for NIC, two (bttn1 and bttn2) for TN, three (btts1, btts2, and btts3) for TS, one (btph) for PH, one (btls) for LS, one (btpt) for PT and one (btl) for L. However, no QTL was detected for TK, LN and W. The 11 main QTLs explained 12.3% to 26.4% of phenotypic variation of traits detected. Additionally, btnic1 and bttn1 respectively controlling NIC and TN showed a good co-segregation, indicating that there could be a certain unknown biological relationship between nicotine biosynthesis and nitrogen metabolism in tobacco leaf. The present study would provide a better understanding for the genetic control and further fine mapping of chemical components and agronomic traits in burley tobacco.