烟草根系杂种优势表现及相关基因差异表达分析

【目的】探究烟草根系性状的杂种优势表现及相关基因差异表达,为深入解析烟草根系吸收和合成相关物质杂种优势的形成机制提供理论依据。【方法】以烟碱和钾含量性状具有杂种优势的12个杂交种及其7个亲本为材料,通过测定根系长度、数量和体积等性状,分析了烟草根系性状的遗传特点及杂种优势表现,并采用实时荧光定量PCR检测烟草根系发育相关基因的差异表达。【结果】7个亲本材料的根系长度为94.80~476.77 cm,根系数量为343~820条,根系体积为0.18~0.61 cm3;12个杂交组合根系长度为285.56~734.75 cm,根系数量为576~1184条,根系体积为0.41~1.01 cm3,3个性状的变异系数为19.97%~29.68%。烟草根系长度、数量和体积的广义遗传力分别为95.49%、92.12%和85.76%,中亲优势组合率分别为91.67%、91.67%和100.00%。根系长度主要受基因的加性效应控制,根系数量和根系体积主要受基因的非加性效应控制,均表现出明显的杂种优势。不同根系发育相关基因的中亲表达优势与根系性状杂种优势存在一定的相关性,其中,NtAUX1和NtARF16基因的中亲表达优势与根系长度杂种优势呈显著(P<0.05,下同)或极显著(P<0.01,下同)相关;NtFLA18基因基因的中亲表达优势与根系数量和体积的杂种优势呈显著或极显著负相关。NtFLA18基因在K326×韭菜坪2号中的相对表达量较双亲下调表达,NtAUX1基因呈显性表达模式,NtARF16基因的相对表达量较双亲上调表达,这些基因的表达模式与烟草根系杂种优势的形成有关。【结论】烟草根系长度、数量和体积均具有较强的遗传率和普遍的杂种优势,可利用杂种优势选育出根系发达的烟草新种质。GDH88、Va116、南江三号和G70可作为改良根系的优良亲本;K326×GDH88、Va116×毕纳1号、G70×韭菜坪2号、G70×南江三号和K326×韭菜坪2号可作为培育优良根系构型的重要储备材料。

Performance of heterosis in tobacco roots and differential expression analysis of related genes

【Objective】To explore the heterosis of tobacco root traits and the differential expression of related genes,so as to provide theoretical basis for in-depth analysis of the formation of heterosis of tobacco root absorption and synthesis of related substances.【Method】Using 12 hybrids and 7 parents with heterosis in nicotine and potassium content traits as materials,the genetic characteristics and heterosis of tobacco root traits were analyzed by measuring root length,quantity and volume,and the differential expression of genes related to tobacco root development was detected by real-time fluorescence quantitative PCR.【Result】The root length of the seven parent materials was 94.80-476.77 cm,the number of roots was 343-820,and the root volume was 0.18-0.61 cm3. The root length of 12 hybrid combinations was 285.56-734.75cm,the number of roots was 576-1184,the root volume was 0.41-1.01 cm3,and the coefficient of variation of the three traits was 19.97%-29.68%. The broad heritability of tobacco root length,quantity and volume was 95.49%,92.12% and 85.76% respectively,and the combination rate of mid-parent dominance was 91.67%,91.67% and 100.00% respectively.The root length is mainly controlled by the additive effect of genes,and the root number and root volume were mainly controlled by the non-additive effect of genes,showing obvious heterosis. There was a certain correlation between the mid-parent expression superiority of different root development-related genes and the root trait heterosis,among which,the midparent expression superiority of NtAUX1 and NtARF16 genes was significantly(P<0.05,the same below) or extremely significantly(P<0.01,the same below) related to the root length heterosis.The mid-parent expression superiority of NtFLA18 gene was significantly or extremely significantly negatively correlated with the heterosis of root quantity and volume. The relative expression of NtFLA18 gene in K326×Jiucaiping No. 2 was down-regulated than that of its parents,NtAUX1 gene was dominant,and NtARF16 gene was up-regulated than that of its parents. The expression pattern of these genes was related to the formation of tobacco root heterosis.【Conclusion】The root length,root quantity and root volume of tobacco have strong heritability and universal heterosis,which can be used to select new tobacco germplasm with developed roots. GDH88,Va116,Nanjiang No. 3 and G70 can be used as excellent parents for root improvement;K326×GDH88,Va116×Bina No.1,G70×Jiucaiping No.2,G70×Nanjiang No.3 and K326×Jiucaiping No.2 can be used as an important reserve materials for cultivating excellent root architecture.