The sub-cellular localisation of the potato (Solanum tuberosum L.) carotenoid biosynthetic enzymes, CrtRb2 and PSY2
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Carotenoids are isoprenoids with important biological roles both for plants and animals. The yellow flesh colour of potato (Solanum tuberosum L.) tubers is a quality trait dependent on the types and levels of carotenoids that accumulate. The carotenoid biosynthetic pathway is well characterised, facilitating the successful engineering of carotenoid content in numerous crops including potato. However, a clear understanding concerning the factors regulating carotenoid accumulation and localisation in plant storage organs, such as tubers, is lacking. In the present study, the localisation of key carotenoid biosynthetic enzymes was investigated, as one of the unexplored factors that could influence the accumulation of carotenoids in potato tubers. Stable transgenic potato plants were generated by over-expressing β-CAROTENE HYDROXYLASE 2 (CrtRb2) and PHYTOENE SYNTHASE 2 (PSY2) genes, fused to red fluorescent protein (RFP). Gene expression and carotenoid levels were both significantly increased, confirming functionality of the fluorescently tagged proteins. Confocal microscopy studies revealed different sub-organellar localisations of CrtRb2-RFP and PSY2-RFP within amyloplasts. CrtRb2 was detected in small vesicular structures, inside amyloplasts, whereas PSY2 was localised in the stroma of amyloplasts. We conclude that it is important to consider the location of biosynthetic enzymes when engineering the carotenoid metabolic pathway in storage organs such as tubers.
KeywordsAmyloplast Carotenoid Localisation Plastid Potato Tuber
Green fluorescent protein
High-performance liquid chromatography
Red fluorescent protein
This work was funded by the Scottish Government Rural and Environment Science and Analytical Services Division and EU-FP7 METAPRO 244348.
Conflict of interest
- Brandizzi F, Snapp EL, Roberts AG, Lippincott-Schwartz J, Hawes C (2002) Membrane protein transport between the endoplasmic reticulum and the golgi in tobacco leaves is energy dependent but cytoskeleton independent: evidence from selective photobleaching. Plant Cell 14:1293–1309PubMedCrossRefGoogle Scholar
- Ducreux LJM, Morris WL, Prosser IM, Morris JA, Beale MH, Wright F, Shepherd T, Bryan GJ, Hedley PE, Taylor MA (2008) Expression profiling of potato germplasm differentiated in quality traits leads to the identification of candidate flavour and texture genes. J Exp Bot 59:4219–4231PubMedCrossRefGoogle Scholar
- Li H-M, Chiu C-C (2010) Protein transport into chloroplasts. In S Merchant, WR Briggs, D Ort, eds, Ann Rev Plant Biol 61: 157–180Google Scholar
- Naested H, Holm A, Jenkins T, Nielsen HB, Harris CA, Beale MH, Andersen M, Mant A, Scheller H, Camara B, Mattsson O, Mundy J (2004) Arabidopsis VARIEGATED 3 encodes a chloroplast targeted, zinc-finger protein required for chloroplast and palisade cell development. J Cell Sci 117:4807–4818PubMedCrossRefGoogle Scholar
- Rochasosa M, Sonnewald U, Frommer W, Stratmann M, Schell J, Willmitzer L (1989) Both developmental and metabolic signals activate the promoter of a class I patatin gene. EMBO J 8:23–29Google Scholar
- Ruiz-Sola MA, Rodriguez-Concepcion M (2012) Carotenoid biosynthesis in Arabidopsis: a colorful pathway. Arabidopsis Book/Am Soc Plant Biol 10:e0158Google Scholar