Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, USA.
BMC Res Notes. 2022 Sep 6;15(1):291. doi: 10.1186/s13104-022-06188-9.
There is great interest in developing tobacco plants containing minimal amounts of the addictive compound nicotine. Quinolate phosphoribosyltransferase (QPT) is an important enzyme both for primary (NAD production) and secondary (pyridine alkaloid biosynthesis) metabolism in tobacco. The duplication of an ancestral QPT gene in Nicotiana species has resulted in two closely related QPT gene paralogs: QPT1 which is expressed at modest levels throughout the plant, and QPT2 which is coordinately regulated with genes dedicated to alkaloid biosynthesis. This study evaluated the utility of knocking out QPT2 function as a means for producing low alkaloid tobacco plants.
CRISPR/Cas9 vectors were developed to specifically mutate the tobacco QPT2 genes associated with alkaloid production. Greenhouse-grown qpt2 plants accumulated dramatically less nicotine than controls, while displaying only modest growth differences. In contrast, when qpt2 lines were transplanted to a field environment, plant growth and development was severely inhibited. Two conclusions can be inferred from this work: (1) QPT1 gene function alone appears to be inadequate for meeting the QPT demands of the plant for primary metabolism when grown in a field environment; and (2) the complete knockout of QPT2 function is not a viable strategy for producing agronomically useful, low nicotine tobaccos.
人们对于开发含有少量成瘾化合物尼古丁的烟草植物非常感兴趣。喹啉酸磷酸核糖基转移酶（QPT）是烟草中初级（NAD 产生）和次级（吡啶生物碱生物合成）代谢的重要酶。Nicotiana 物种中祖先 QPT 基因的复制导致了两个密切相关的 QPT 基因同源物：QPT1 在整个植物中以适度的水平表达，而 QPT2 与专门用于生物碱生物合成的基因协调调节。本研究评估了敲除 QPT2 功能作为生产低生物碱烟草植物的一种手段的实用性。
开发了 CRISPR/Cas9 载体，以专门突变与生物碱生产相关的烟草 QPT2 基因。与对照相比，qpt2 植物在温室中积累的尼古丁明显减少，而生长差异仅略有增加。相比之下，当 qpt2 系被移植到田间环境时，植物的生长和发育受到严重抑制。从这项工作中可以得出两个结论：（1）当在田间环境中生长时，QPT1 基因的单独功能似乎不足以满足植物对初级代谢的 QPT 需求；（2）完全敲除 QPT2 功能不是生产具有农艺用途、低尼古丁烟草的可行策略。
