Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran
Phytoene synthase (Psy) and Phytoene desaturase (Pds) are the first two regulatory enzymes in the carotenoids biosynthetic pathway. The genes Psy and Pds are under transcriptional control in many photosynthetic organisms. In the present study, using quantitative real time- PCR (qRT-PCR), the effects of uncoated and gum-Arabic coated PbS nanoparticles (GA-coated PbS NPs) and light intensity on the mRNA levels of Pds were investigated. Relative to mRNA level of Pds at 100 µmol photon m-2 s-1 light intensity (control culture), 2.2-fold increase in transcript levels occurred after 12 h of exposure to higher light intensity, which is significantly (P<0.05) different compared to control. After 48 h of exposure, the mRNA level of Pds was reduced to that in control. This indicates that light intensity regulates Pds at the mRNA level. In the presence of uncoated and GA-coated PbS NPs, the transcript levels of Pds were decreased over time, with uncoated PbS NPs having more inhibitory effects on mRNA levels compared to GA-coated PbS NPs. This shows that PbS NPs have adverse effects on transcription or post transcriptional processing and coating nanoparticles with biopolymers reduces their toxicity to organisms. Being under control, it seems that genetic manipulation of Pds may result in increased biotechnological production of carotenoids by D. salina.
1. Borowitzka MA, Borowitzka LJ, Kessly D. Effects of salinity increase on carotenoid accumulation in the green alga Dunaliella salina. J Appl Phycol 1990;2:111-119.
2. Lers A, Biener Y, Zamir A. Photoinduction of massive betacarotene accumulation by the alga Dunaliella bardawil: kinetics and dependence on gene activation. Plant Physiol 1990;93:389-395.
3. Bartley GE, Scolnik PA. Plant carotenoids: pigments for photoprotection, visual attraction, and human health. Plant Cell 1995;7:1027-1038.
4. Phillips MA, Leon P, Boronat A, Rodriguez-Concepcion M. The plastidial MEP pathway: unified nomenclature and resources. Trends Plant Sci 2008;13:619-623.
5. Campisi L, Fambrini M, Michelotti V, Salvini M, Giuntini D, Pugliesi C. Phytoene accumulation in sunflower decreases the transcript levels of the phytoene synthase gene. Plant Growth Regul 2006;48:79-87.
6. Salvini M, Bernini A, Fambrini M, Pugliesi C. cDNA cloning and expression of the phytoene synthase gene in sunflower. J Plant Physiol 2005;162:479-484.
7. Cazzonelli, C.I., and Pogson, B.J. Source to sink: regulation of carotenoid biosynthesis in plants. Trends Plant Sci 2010;15:266-274.
8. Sánchez-Estudillo L, Freile-Pelegrin Y, Rivera-Madrid R, Robledo D, Narvaez-Zapata JA. Regulation of two photosynthetic pigment-related genes during stress-induced pigment formation in the green alga, Dunaliella salina. Biotechnol Lett 2006;28:787-791.
9. Coesel SN, Teles LM, Ramos AA, Henriques NM, Cancela L, Varela JCS. Nutrient limitation is the main regulatory factor for carotenoids accumulation and for Psy and Pds steady state transcript levels in Dunaliella salina (Chlorophyta) exposed to high light and salt stress. Mar Biotechnol 2008;10:602-611.
10. Simkin AJ, Laboure AM, Kuntz M, Sandmann G. Comparison of carotenoid content, gene expression and enzyme levels in tomato (Lycopersicon esculentum) leaves. Z Naturforsch [C] 2003;58:371-380.
11. Simkin AJ, Zhu C, Kuntz M, Sandmann G. Light-dark regulation of carotenoid biosynthesis in pepper (Capsi cumannuum) leaves. J Plant Physiol 2003;160:439-443.
12. Racchi ML. Antioxidant defenses in plants with attention to prunus and citrus spp. Antioxidant 2013;2:340-369.
13. Perreault F, Popovic R, Dewez D. Different toxicity mechanisms between bare and polymer coated copper oxide nanoparticles in Lemna gibba. Environ. Pollut 2014;185:219-227.
14. Andersen C, King G, Plocher M, Storm M, Rygiewicz P, Tumburu L, Reichman J. Effect of nTiO2 and nCeO2 nanoparticles on gene expression, germination, and early development in plants. International Congress on Safety of Engineered Nanoparticles and Nanotechnologies, Helsinki, Finland. 2015.
15. Ben-Amotz A, Shaish A, Moradhay A. Mode of action of massively accumulated β- carotene of Dunaliella bardawill in protecting the alga against damage by excess irradiation. Plant Physiol 1989;91:1040-1043.
16. Zamani H, Moradshahi A, Jahromi HD, Sheikhi MH. Influence of PbS nanoparticle polymer coating on their aggregation behavior and toxicity to the green algae Dunaliella salina. Aquatic Toxicol 2014;154:176-183.
17. Li F, Vallabhaneni R, Wurtzel E. PSY3, a new member of the phytoene synthase gene family conserved in the Poaceae and regulator of abiotic stress-induced root carotenogenesis. Plant Physiol 2008;146:1333-1345.
18. Cazzonelli CI, Pogson BJ. Source to sink: regulation of carotenoid biosynthesis in plants. Trends in Plant Sci 2010;15:266-274.
19. Rabbani S, Beyer P, Von Lintig J, Hugueney P, Kleinig H. Induced beta-carotene synthesis driven by triacylglycerol deposition in the unicellular alga Dunaliella bardawil. Plant Physiol 1998;116:1239-1248.
20. Schaeffer L, Sandmann M, Woitsch S, Sandmann G. Coordinate up-regulation of carotenoid biosynthesis as a response to light stress in Synechococcus PCC7942. Plant Cell Environ 2006;29:1349-1356.
21. Bohne F, Linden H. Regulation of carotenoid biosynthesis genes in response to light in Chlamydomonas reinhardtii. Biochim Biophys Acta 2002;1579:26-34.
22. Grunewald K, Eckert M, Hirschberg J, Hagen C. Phytoene desaturase is localized exclusively in the chloroplast and upregulated at the mRNA level during accumulation of secondary carotenoids in Haematococcus pluvialis (Volvocales, Chlorophyceae). Plant Physiol 2000;122:1261-1268.
23. Peralta-Videa JR, Zhao L, Lopez-Moreno ML, de la Rosa G, Hong J, Gardea Torresdey JL. 011. Nanomaterials and the environment: a review for the biennium 2008–2010. J Hazard Mater 2011;186:1-15.
24. Kumari M, Khan SS, Pakrashi S, Mukherijee A, Chandrasekaran N. Cytogenetic And genotoxic effects of zinc oxide nanoparticles on root cells of Allium cepa. J Hazard Mater 2011;190:613-621.
25. Xia T, Kovochich M, Liong M, Madler L, Gilbert B, Shi H, Yeh J, Zink JI, Nel AE. Comparison of the mechanism of toxicity of zinc oxide and cerium oxide nanoparticles based on dissolution and oxidative stress properties. ACS Nano 2028; 2:2124-2134.
26. Lee SH, Pie j, Kim Y, Lee HR, Son SW, Kim M. Effects of zinc oxide nanoparticles on gene expression profile in human keratinocytes. Mol Cell Toxicol 2012;8:113-118.
27. Kaveh R, Li YS, Ranjbar S, Tehrani R, Brueck CL, Van Aken B. Changes in Arabidopsis thaliana gene expression in response to silver nanoparticles and silver ions. Environ Sci Technol 2013;47:10637-44.