College of Tobacco, Guizhou University, Guiyang, China.
Key Laboratory of Tobacco Quality in Guizhou Province, Guiyang, China.
BMC Plant Biol. 2024 Oct 15;24(1):962. doi: 10.1186/s12870-024-05670-9.
Nicotine exhibits obvious heterosis, which can be used to create Nicotiana tabacum L. (tobacco) varieties with varying nicotine content. However, the reasons for the formation of nicotine heterosis and its relationship to nicotine transport and accumulation remain unknown. This study conducted a comprehensive analysis of six tobacco hybrids with varying heterosis levels and their parent materials from various aspects, such as phenotype, physiology, and transcriptomics. The results showed that the direct path coefficient of transport heterosis to nicotine heterosis was highest in hybrids, at 0.98, and a highly significant positive correlation between the two. The plant height, thick stalk circumference, large flow of tissue fluid in the stalk, and high nicotine concentration of tobacco were the underlying factors that led to the strong nicotine transport capacity of hybrids. The formation of nicotine transport heterosis in hybrids was mainly influenced by non-additive gene effects (accounting for 89.93%), with over-dominant effects playing a dominant role (accounting for 58.79%). Among non-additive expression DEGs, nicotine transporter related multi antimicrobial extrusion protein, drug/metabolite transporter, ABC family transporter, and glutathione S-transferase were significantly upregulated in hybrid strains. The RT-qPCR results indicated that these genes related nicotine transport also exhibited heterosis at the expression level. Our results revealed that the formation of nicotine heterosis is mainly achieved by enhancing the nicotine transport capacity in hybrids. The results are not only beneficial for promoting the theoretical study of nicotine heterosis in tobacco and the breeding and utilization of hybrids, but are also of great significance for guiding nicotine production and promoting its multipurpose utilization.
尼古丁表现出明显的杂种优势，可以用来培育具有不同尼古丁含量的烟草品种。然而，尼古丁杂种优势的形成原因及其与尼古丁运输和积累的关系尚不清楚。本研究从表型、生理和转录组学等多个方面对 6 个具有不同杂种优势水平的烟草杂种及其亲本材料进行了综合分析。结果表明，杂种中运输杂种优势对尼古丁杂种优势的直接通径系数最高，为 0.98，两者之间呈高度显著正相关。烟草株高、茎粗、茎组织液流量大、尼古丁浓度高是导致杂种尼古丁运输能力强的内在因素。杂种中尼古丁运输杂种优势的形成主要受非加性基因效应的影响（占 89.93%），超显性效应起主导作用（占 58.79%）。在非加性表达差异基因中，尼古丁转运体相关多抗菌外排蛋白、药物/代谢物转运体、ABC 家族转运体和谷胱甘肽 S-转移酶在杂种品系中显著上调。RT-qPCR 结果表明，这些与尼古丁运输相关的基因在表达水平上也表现出杂种优势。我们的研究结果表明，尼古丁杂种优势的形成主要是通过增强杂种的尼古丁运输能力来实现的。这些结果不仅有利于促进烟草尼古丁杂种优势的理论研究和杂种的选育和利用，而且对指导尼古丁的生产和促进其多用途利用具有重要意义。
