Environmental and Genetic Factors Associated with Solanesol Accumulation in Potato Leaves

Abstract

Solanesol is a high value 45-carbon, unsaturated, all-trans-nonaprenol isoprenoid. Recently solanesol has received particular attention because of its utility, both in its own right and as a precursor in the production of numerous compounds used in the treatment of disease states. Solanesol is found mainly in solanaceous crops such as potato, tomato, tobacco and pepper where it accumulates in the foliage. There is considerable potential to explore the extraction of solanesol from these sources as a valuable co-product. In this study we have characterized the genetic variation in leaf solanesol content in a biparental, segregating diploid potato population. We demonstrate that potato leaf solanesol content is genetically controlled and identify several quantitative trait loci associated with leaf solanesol content. Transient over-expression of genes from the methylerythritol 4-phosphate (MEP) and mevalonic acid (MVA) pathways, either singly or in combination, resulted in enhanced accumulation of solanesol in leaves of Nicotiana benthamiana, providing insights for genetically engineering the pathway. We also demonstrate that in potato, leaf solanesol content is enhanced by up to six-fold on exposure to moderately elevated temperature and show corresponding changes in expression patterns of MEP and MVA genes. Our combined approaches offer new insights into solanesol accumulation and strategies for developing a bio-refinery approach to potato production.

Strategies for the production of biochemicals in bioenergy crops

“…Similarly, overexpression of Synechosystis DXR in tobacco chloroplasts increased the production of isoprenoids (i.e., chlorophyll a, β-carotene, lutein, antheraxanthin, solanesol and β-sitosterol) [196]. Co-expression of DXR and solanesyl diphosphate synthase (SDS) in potato can significantly enhance the levels of solanesol compared to DXR alone [197]. In addition, higher DXR levels have been associated with a role in arbuscule development in the roots of several monocot plants (e.g., wheat, maize, rice, and barley) along with increased apocarotenoid biosynthesis [198,199].…”

RNA-seq Analysis of Solanesol Biosynthesis Genes in <em>Nicotiana tabacum</em>

“…Solanesol is a long-chain polyisoprenoid alcohol that mainly accumulates in solanaceous plants, especially tobacco [1,3,12], and is an important intermediate in the synthesis of ubiquinones and anticancer drugs. Because the chemical synthesis of solanesol is difficult [11], we assessed some aspects of its biosynthesis in tobacco plants and observed differential accumulation of solanesol in the leaves, stems, and roots of tobacco plants, with the content in leaves being the highest (Figure 2A).…”

“…Therefore, the S3 stage can be considered as the most appropriate period for harvesting tobacco leaves for solanesol extraction. However, since the accumulation of solanesol is reportedly influenced by genetic and environmental factors [1,3,12,15], for the optimal extraction of solanesol from fresh tobacco leaves, the appropriate harvesting period was suggested to be determined for individual tobacco varieties and their specific environmental conditions.…”

“…Solanesol is a noncyclic terpene alcohol synthesized by the condensation of nine isoprene units, and this molecule is a precursor in the synthesis of ubiquinones and anti-cancer drugs, such as coenzyme Q10, vitamin K2, and N-solanesyl-N, N′-bis (3,4-dimethoxybenzyl) ethylenediamine (SDB) [1][2][3]. Coenzyme Q10 has anti-oxidant and anti-aging properties and is reported to strengthen the body's immune system and cardiovascular function, improve brain health, and moderate blood lipids.…”

Solanesol Biosynthesis in Plants

“…Solanesol is a non-cyclic terpene alcohol composed of nine isoprene units, and serves as a key intermediate in the synthesis of ubiquinone-based drugs and supplements such as coenzyme Q10, vitamin K2, and the anti-cancer agent synergizer N -solanesyl- N , N ′-bis(3,4-dimethoxybenzyl) ethylenediamine (SDB) [ 1 , 2 , 3 ]. Solanesol was first isolated from tobacco ( Nicotiana tabacum ), and has been subsequently reported in other solanaceous plants, including potato ( Solanum tuberosum ), tomato ( Solanum lycopersicum ), eggplant ( Solanum melongena ), and pepper ( Capsicum annuum ) [ 3 , 4 ].…”