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Title: Novel bioassay for the discovery of inhibitors of the 2-C-Methyl-D-Erythritol 4-Phosphate (MEP) and terpenoid pathways leading to carotenoid biosynthesis

Author
item CORNIANI, NATÁLIA - Universidad De Sao Paulo
item VELINI, EDIVALDO - Universidad De Sao Paulo
item SILVA, FERDINANDO M. L - Universidad De Sao Paulo
item NANAYAKKARA, DHAMMIKA N.P. - University Of Mississippi
item WITSCHEL, MATTHIAS - Basf, Germany
item Dayan, Franck

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2014
Publication Date: 7/31/2014
Citation: Corniani, N., Velini, E.D., Silva, F., Nanayakkara, D., Witschel, M., Dayan, F.E. 2014. Novel bioassay for the discovery of inhibitors of the 2-C-Methyl-D-Erythritol 4-Phosphate (MEP) and terpenoid pathways leading to carotenoid biosynthesis. PLoS One. 98:E103704.

Interpretive Summary: The synthesis of carotenoids is an important pathway for herbicide discovery. We have developed a new, simple and inexpensive bioassay that can detect the activity of compounds inhibiting this pathway. This concept was tested with known inhibitors of steps of the MEP pathway and validated against representative herbicides known to target processes outside of the pathways involved in the synthesis of carotenoids. This assay enables the rapid screen of new inhibitors of enzymes preceding the synthesis of phytoene, though there are some limitations related to the non-specific effect of some inhibitors on this assay.

Technical Abstract: The 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway leads to the synthesis of isopentenyl-phosphate (IPP) in plastids. It is a major branch point providing precursors for the synthesis of carotenoids, tocopherols, plastoquinone and the phytyl chain of chlorophylls, as well as the hormones abscisic acid and gibberellins. Consequently, disruption of this pathway is harmful to plants. We developed an in vivo bioassay that can measure the carbon flow through the carotenoid pathway. Leaf cuttings are incubated in the presence of a phytoene desaturase inhibitor to induce phytoene accumulation. Any compound reducing the level of phytoene accumulation is likely to interfere with either one of the steps in the MEP pathway or the synthesis of geranylgeranyl pyrophosphate. This concept was tested with known inhibitors of steps of the MEP pathway. The specificity of this in vivo bioassay was also verified by testing representative herbicides known to target processes outside of the MEP and carotenoid pathways. This assay enables the rapid screen of new inhibitors of enzymes preceding the synthesis of phytoene, though there are some limitations related to the non-specific effect of some inhibitors on this assay.