Organ- and Growing Stage-Specific Expression of Solanesol Biosynthesis Genes in Nicotiana tabacum Reveals Their Association with Solanesol Content.

Ning Yan,Xinmin Liu,Yongmei Du,John Shi,Yanhua Liu,Zhongfeng Zhang,Michael Timko,Hongbo Zhang

doi:10.3390/molecules21111536

Abstract

Solanesol is a noncyclic terpene alcohol that is composed of nine isoprene units and mainly accumulates in solanaceous plants, especially tobacco (Nicotiana tabacum L.). In the present study, RNA-seq analyses of tobacco leaves, stems, and roots were used to identify putative solanesol biosynthesis genes. Six 1-deoxy-d-xylulose 5-phosphate synthase (DXS), two 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), two 2-C-methyl-d-erythritol 4-phosphate cytidylyltransferase (IspD), four 4-diphosphocytidyl-2-C-methyl-d-erythritol kinase (IspE), two 2-C-methyl-d-erythritol 2,4-cyclo-diphosphate synthase (IspF), four 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase (IspG), two 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase (IspH), six isopentenyl diphosphate isomerase (IPI), and two solanesyl diphosphate synthase (SPS) candidate genes were identified in the solanesol biosynthetic pathway. Furthermore, the two N. tabacum SPS proteins (NtSPS1 and NtSPS2), which possessed two conserved aspartate-rich DDxxD domains, were highly homologous with SPS enzymes from other solanaceous plant species. In addition, the solanesol contents of three organs and of leaves from four growing stages of tobacco plants corresponded with the distribution of chlorophyll. Our findings provide a comprehensive evaluation of the correlation between the expression of different biosynthesis genes and the accumulation of solanesol, thus providing valuable insight into the regulation of solanesol biosynthesis in tobacco.

Highlights

Solanesol is a medically important noncyclic terpene alcohol that is synthesized by the condensation of nine isoprene units
Our results revealed that the chlorophyll content in the leaves, stems, and roots of tobacco plants (Figure 6A) corresponded with the distribution of solanesol (Figure 1A), which is consistent with other studies that have suggested that solanesol is synthesized in chloroplasts [3,12,14], and our results indicate that solanesol mainly accumulates in green plant tissues
Based on the similarity of amino acid sequences, six D-xylulose 5-phosphate synthase (DXS), two D-xylulose 5-phosphate reductoisomerase (DXR), two IspD, four IspE, two IspF, four IspG, two IspH, six isopentenyl diphosphate isomerase (IPI), and two solanesyl diphosphate synthase (SPS) candidate genes were identified in the solanesol biosynthetic pathway of tobacco (Figure 2)

Summary

Introduction

Solanesol is a medically important noncyclic terpene alcohol that is synthesized by the condensation of nine isoprene units. Coenzyme Q10 has potential usefulness in the treatment of migraines, neurodegenerative diseases, hypertension, and cardiovascular diseases [2,3,4,5], and it is being used as a dietary supplement by patients with type-2 diabetes [6]. Molecules 2016, 21, 1536; doi:10.3390/molecules21111536 www.mdpi.com/journal/molecules blood coagulation, and improves arterial stiffness [7]; and SDB, mediated by P-proteins, is used in theosteoporosis, treatment ofpromotes several types drug resistance in tumours and stiffness plays a synergistic role with certain bloodofcoagulation, and improves arterial [7]; and SDB, mediated by. In Recently, reported solanesol can protect human hepatic synergistic role with certainoxidative antitumorinjury drugs via [8,9].

Results

Discussion

Conclusion