Transcriptome analysis of the monoterpene biosynthesis pathway in petals of Lilium ‘Siberia’ at different flowering stages
Tang Biao1, Hu Zeng-Hui1,2,3, Leng Ping-Sheng1,2,3
1. College of Landscape, Beijing University of Agriculture, Beijing 102206, China;
2. Beijing Collaborative Innovation Center for Eco-environmental Improvement with Forestry and Fruit Trees, Beijing 102206, China;
3. Beijing Laboratory of Urban and Rural Ecological Environment, Beijing 102206, China
Lilium ‘Siberia’, a typical and fragrant oriental hybrid lily, emits a large amount of monoterpenes, which shows considerable developmental emissions. To date, however, the mechanisms for this remain largely unknown. In this study, we used RNA sequencing (RNA-seq) to determine the petal transcriptome at four different flowering stages, including bud (BS), half-bloom (HS), full-bloom (FS), and late-bloom stages (LS), and analyzed differentially expressed genes(DEGs)to investigate the molecular mechanism of monoterpene biosynthesis. Based on the transcriptome sequencing, we obtained 56.28 Gb of clean bases and 223.40 Mb of clean reads, which were assembled into 124 233 unigenes, 35 749 of which were annotated. The genes in the terpenoid backbone biosynthesis pathway showed significantly different expression at different flowering stages. The gene expression levels of 1-deoxy-D-xylulose 5-phosphate synthase(DXS),1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), 4-hydroxy-3-methylbut-2-enyl diphosphate synthase (HDS), 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR), and geranyl diphosphate synthase (GPS) first increased and then decreased with flowering stage. The gene expression of ocimene synthase (OCS) exhibited a similar pattern, with a maximum at FS, consistent with monoterpene emission in our previous study. The gene expression of HMG-CoA reductase (HMGR) in the mevalonate (MVA) pathway also presented the same pattern; however, the gene expression patterns of solanesyl-diphosphate synthase (SDS) and geranylgerany1 diphosphate reductase (GGDR) showed the opposite trend and were the lowest during FS in the branched pathway downstream of monoterpene biosynthesis. We demonstrated that the gene expression of key enzymes in the 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway regulated the biosynthesis of monoterpenes with flower development, resulting in high release during FS. Moreover, the high activation level of the MVA pathway and the depressed branched metabolic pathway of ubiquinone and other terpenoid-quinones during FS may partly contribute to monoterpene biosynthesis.
[1] Dudareva N, Pichersky E, Gershenzon J. Biochemistry of plant volatiles[J]. Plant Physiol, 2004, 135:1893-1902.
[2] Raguso RA. Wake up and smell the roses:the ecology and evolution of floral scent[J]. Annu Rev Ecol Evol Syst, 2008, 39(1):549-569.
[3] Parép W, Tumlinson JH. De novo biosynthesis of volatiles induced by insect herbivory in cotton plants[J]. Plant Physiol, 1997, 114:1161-1167.
[4] Huang M, Sanchez-Moreiras AM, Abel C, Sohrabi R, Lee S, et al. The major volatile organic compound emitted from Arabidopsis thaliana flowers, the sesquiterpene (E)-β-caryophyllene, is a defense against a bacterial pathogen[J]. New Phytol, 2012, 193:997-1008.
[5] Gao X, Yao L. Preliminary study on the combinations of specific aromatic plants for Hypotensive healthcare[J]. Chin Landscape Archit, 2011, 27:37-38.
[6] Jo H, Rodiek S, Fujii E, Miyazaki Y, Park BJ, Ann SW. Physiological and psychological response to floral scent[J]. Hortscience, 2103, 48:82-88.
[7] Sharkey TD, Gray DW, Pell HK, Breneman SR, Topper L. Isoprene synthase genes form a monophyletic clade of acyclic terpene synthases in the Tps-b terpene synthase family[J]. Evolution, 2013, 67:1026-1040.
[8] Feng L, Chen C, Li T, Wang M, Tao J, et al. Flowery odor formation revealed by differential expression of monoterpene biosynthetic genes and monoterpene accumulation in rose (Rosa rugosa Thunb.)[J]. Plant Physiol Biochem, 2014, 75:80-88.
[9] Fenske MP, Hewett Hazelton KD, Hempton AK, Shim JS, Yamamoto BM, et al. Circadian clock gene LATE ELONGATED HYPOCOTYL directly regulates the timing of floral scent emission in Petunia[J]. Proc Natl Acad Sci USA, 2015, 112:9775-9780.
[10] Hu Z, Li T, Zheng J, Leng P, Yang K, Zhang KZ. A new monoterpene synthase gene involved in the monoterpene production from Lilium ‘Siberia’[J]. J Anim Plant Sci, 2016, 26:1389-1398.
[11] Bera P, Mukherjee C, Mitra A. Enzymatic production and emission of floral scent volatiles in Jasminum sambac[J]. Plant Sci, 2017, 256:25-38.
[12] Salzmann CC, Cozzolino S, Schiestl FP. Floral scent in food-deceptive orchids:species specificity and sources of variability[J]. Plant Biol, 2007, 9:720-729.
[13] Yang X, Zhao J, Zheng J, Leng P, Li X, et al. Analysis of floral scent emitted from Syringa plants[J]. J Forestry Res, 2016, 27:273-281.
[14] Dudareva N, Pichersky E. Biochemical and molecular genetic aspects of floral scents[J]. Plant Physiol, 2000, 122:627-633.
[15] Tholl D. Biosynthesis and biological functions of terpenoids in plants[J]. Adv Biochem Eng Biotechnol, 2015, 148:63-106.
[16] Hendel-Rahmanim K, Masci T, Vainstein A, Weiss D. Diurnal regulation of scent emission in rose flowers[J]. Planta, 2007, 226:1491-1499.
[17] Zhao J, Hu Z, Leng P, Zhang H, Cheng F. Fragrance composition in six tree peony cultivars[J]. Korean J Hortic Sci Technol, 2012, 30:617-625.
[18] Hao R, Zhang Q, Yang W, Wang J, Cheng T, et al. Emitted and endogenous floral scent compounds of Prunus mume and hybrids[J]. Biochem System Ecol, 2014, 54:23-30.
[19] Grabherr MG, Haas BJ, Yassour M, Levin JZ, Thompson DA, et al. Full-length transcriptome assembly from RNA-Seq data without a reference genome[J]. Nat Biotechnol, 2011, 29:644-652.
[20] Pertea G, Huang X, Liang F, Antonescu V, Sultana R, et al. TIGR gene indices clustering tools (TGICL):a software system for fast clustering of large EST datasets[J]. Bioinformatics, 2003, 19:651-652.
[21] Estévez JM, Cantero A, Reindl A, Reichler S, León P.1-Deoxy-d-xylulose-5-phosphate synthase, a limiting enzyme for plastidic isoprenoid biosynthesis in plants[J]. J Biol Chem, 2001, 276:22901-22909.
[22] Yang J, Adhikari MN, Liu H, Xu H, He G, et al. Characterization and functional analysis of the genes encoding 1-deoxy-D-xylulose-5-phosphate reductoisomerase and 1-deoxy-D-xylulose-5-phosphate synthase, the two enzymes in the MEP pathway, from Amomum villosum Lour[J]. Mol Biol Rep, 2012, 39, 8287-8296.
[23] Hsieh WY, Hsieh MH. The amino-terminal conserved domain of 4-hydroxy-3-methylbut-2-enyl diphosphate reductase is critical for its function in oxygen-evolving photosynthetic organisms[J]. Plant Signal Behav, 2015, 10:e988072.
[24] Page JE, Hause G, Raschke M, Gao W, Schmidt J, et al. Functional analysis of the final steps of the 1-deoxy-D-xylulose 5-phosphate (DXP) pathway to isoprenoids in plants using virus-induced gene silencing[J]. Plant Phy-siol, 2004, 134:1401-1413.
[25] Zhou J, Wang C, Yang L, Choi ES, Kim SW. Geranyl diphosphate synthase:An important regulation point in balancing a recombinant monoterpene pathway in Escherichia coli[J]. Enzyme Microb Tech, 2015, 68:50-55.
[26] Rico J, Pardo E, Orejas M. Enhanced production of a plant monoterpene by overexpression of the 3-hydroxy-3-methylglutaryl coenzyme A reductase catalytic domain in Saccharomyces cerevisiae[J]. Appl Environ Microb, 2010, 76:6449-6454.