Functional characterization and comparison of lycopene epsilon-cyclase genes in Nicotiana tabacum

• Published in: BMC plant biology Vol. 22; no. 1; p. 252
• Main Authors: Song, Weina, Wei, Fang, Gao, Shuwen, Dong, Chen, Hao, Jianfeng, Jin, Lifeng, Li, Feng, Wei, Pan, Guo, Jinggong, Wang, Ran
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 21.05.2022; BioMed Central; BMC
• Subjects: allotetraploidy; Binding sites; biochemical pathways; Bioinformatics; Biosynthesis; Carotenoid biosynthetic pathway (CBP); Carotenoid metabolism; Carotenoids; Carotenoids - metabolism; Chlorophyll; CRISPR; CRISPR-Cas systems; CRISPR/Cas9; Enzymes; Flowers; Fruit - genetics; fruits; Gene expression; Genes; Genetic aspects; Genomes; Growth rate; Hardiness; heat transfer; High light stress; Identification and classification; Intramolecular Lyases - genetics; Isomerases; Leaves; Light; Lycopene; lycopene epsilon-cyclase; Lycopene epsilon-cyclase (ε-LCY); Mutants; Mutation; Nicotiana - metabolism; Nicotiana tabacum; Photosynthesis; Physiological aspects; Plants; Polyploidy; Reactive oxygen species; Seeds; stress tolerance; Tobacco; Tobacco (Plant); China; Lycopene epsilon-cyclase (ε-LCY); CRISPR/Cas9; Carotenoid biosynthetic pathway (CBP); High light stress
• ISSN: 1471-2229; 1471-2229
• DOI: 10.1186/s12870-022-03634-5

Lycopene epsilon-cyclase (ε-LCY) is a key enzyme in the carotenoid biosynthetic pathway (CBP) of higher plants. In previous work, we cloned two Ntε-LCY genes from allotetraploid tobacco (Nicotiana tabacum), Ntε-LCY2 and Ntε-LCY1, and demonstrated the overall effect of Ntε-LCY genes on carotenoid biosynthesis and stress resistance. However, their genetic and functional characteristics require further research in polyploid plants. Here, we used CRISPR/Cas9 to obtain Ntε-LCY2 and Ntε-LCY1 mutants in allotetraploid N.tabacum K326. Ntε-LCY2 and Ntε-LCY1 had similar promoter cis-acting elements, including light-responsive elements. The Ntε-LCY genes were expressed in roots, stems, leaves, flowers, and young fruit, and their highest expression levels were found in leaves. Ntε-LCY2 and Ntε-LCY1 genes responded differently to normal light and high light stress. Both the Ntε-LCY2 and the Ntε-LCY1 mutants had a more rapid leaf growth rate, especially ntε-lcy2-1. The expression levels of CBP genes were increased in the ntε-lcy mutants, and their total carotenoid content was higher. Under both normal light and high light stress, the ntε-lcy mutants had higher photosynthetic capacities and heat dissipation levels than the wild type, and this was especially true of ntε-lcy2-1. The reactive oxygen species content was lower in leaves of the ntε-lcy mutants. In summary, the expression patterns and biological functions of the Ntε-LCY genes Ntε-LCY1 and Ntε-LCY2 differed in several respects. The mutation of Ntε-LCY2 was associated with a greater increase in the content of chlorophyll and various carotenoid components, and it enhanced the stress resistance of tobacco plants under high light.