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Team:Valencia UPV/Project/overview
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Project > Project Overview
Pests cause great economical loses in agriculture and impedes an optimal use of the resources. Treatments used nowadays have some not-so-wanted faces: Pesticides do not target specifically enough to pests and cause alterations in other organisms, and chemical production of sex pheromones is expensive and generates contaminant by-products.
Sexy Plant rises as a pest control strategy based on the use of mating disruption to prevent laying. Mating disruption is based on the release of sex pheromones to the air, so male’s sex pheromones receptors are not able to trace females anymore. This strategy is effectively used in field already with chemically synthesised pheromones [1]. Our final goal is to increase the sustainability of this approach by intercropping few Sexy Plants emitting mating-disrupting pheromones.
Sexy Plant produces and releases in Nicotiana benthamiana several sex pheromones (Z11-16:OH, Z11-16:OAc and Z11-16:Ald) for a broad number of Lepidoptera species (moths). We implemented previous work on production pathways done by Ding et al. [2] into our system to produce the first two pheromones (Z11-16:OH and Z11-16:OAc). We knew about the importance of Z11-16:Aldehide to control a large number of species, so inspired by Hagström approach [3], we introduced Fatty Acid reductase to transform Z11-16:OH to Z11-16:Ald. As result, the sexy plant is able to produce three sex pheromones involved in moth’s mating disruption with 2 or 3 additional enzymes (Figure 1).
Figure 1. Biosynthetic pathway of moth sex pheromones. Sex pheromones are bordered in purple. Taking palmitic acid CoA (16:CoA) as substrate, the expression of the genes AtrΔ11 (Desaturase) and HarFAR (Reductase) leads to the production of Z11-16:OH. By adding the gene EaDAcT (Acetyltransferase) in the previous system, production displaced to obtaining Z11-16:OAc. If a Fatty Acid Reductase (FAO) is included instead of EaDAcT, Z11-16:Ald will be produced.
Biosafety is a major concern in our project. For that reason, we have developed a biosafety module which allows an easy identification of the plant by identity preservation and prevents the plant to spread its genetic material via pollen. Identity preservation is achieved by the production of a chromoprotein so that the plant acquires a differential colour. Dispersion of the genetic material is prevented by male sterility, as results of the tissue-specific expression of a RNAse (Barnase) in tapetum cells under the regulation of the promoter TA29 [4]. This way, autogamous Sexy Plants cannot be self-pollinate and seeds formation is blocked.
In addition, we decided that it was important to enable external control for the production of the pheromones in the Sexy Plant. Therefore we designed a genetic switch to control the activation of sex pheromone biosynthetic pathways. This genetic switch turns on the production of pheromones when a solution containing CuSO4 is sprayed on the plant. Switching ON and OFF the production produces a better use of the plant resources since nutrients can be used for normal metabolism when production is switched off.
The different genetic modules are put together to create the complete system. The complete system resembles an electric circuit, as it’s simply represented in figure 2. Our genetic circuit, once introduced in Nicotiana benthamiana creates the Sexy Plant, a plant to fight moths and avoid damages in crops.
Figure 2. Our system in an electric circuit-like format. The plant’s own metabolism is used as the energy source. The biosecurity module, composed by identity preservation and male sterility parts is always under expression in the system, to ensure the security of the transgenic plant. The pheromone synthetic pathways (A,B or C, depending on the problem pest) are activated using a genetic switch sensitive to Copper Sulfate, so system will not be producing pheromones unless it is activated with Cooper-rich solution.
REFERENCES
- Matsumoto S (2010) Molecular mechanisms underlying sex pheromone production in moths. Biosci Biotechnol Biochem 74: 223-231.
- Hagström A, Wang HL, Lienard MA, Lassance JM, Johansson T, et al. (2013) A moth pheromone brewery: production of (Z)-11-hexadecenol by heterologous co-expression of two biosynthetic genes from a noctuid moth in a yeast cell factory. Microb Cell Fact 12: 125.
- Ding BJ, Hofvander P, Wang HL, Durrett TP, Stymne S, et al. (2014) A plant factory for moth pheromone production. Nat Commun 5: 3353.
- Vanhanen S, West M, Kroon JT, Lindner N, Casey J, Cheng Q et al (2000) A consensus sequence for long-chain fatty-acid alcohol oxidases from Candida identifies a family of genes involved in lipid omega-oxidation in yeast with homologues in plants and bacteria. J Biol Chem. 275, 4445-52.
- Eirich LD, Craft DL, Steinberg L, Asif A, Eschenfeldt WH, et al. (2004) Cloning and characterization of three fatty alcohol oxidase genes from Candida tropicalis strain ATCC 20336. Appl Environ Microbiol 70: 4872-4879.
- Kemp GD, Dickinson FM, Ratledge C (1991) Activity and substrate specificity of the fatty alcohol oxidase of Candida tropicalis in organic solvents. Appl Microbiol Biotechnol. 34(4), 441-445.
- Kemp GD, Dickinson FM, Ratledge (1988) Inducible long chain alcohol oxidase from alkane-grown Candida tropicalis. Appl Microbiol Biotechnol. 29(4), 370-374.
- Sallaud C, Giacalone C, Topfer R, Goepfert S, Bakaher N, et al. (2012) Characterization of two genes for the biosynthesis of the labdane diterpene Z-abienol in tobacco (Nicotiana tabacum) glandular trichomes. Plant J 72: 1-17.
- Mett VL, Lochhead LP, Reynolds PH (1993) Copper-controllable gene expression system for whole plants. Proc Natl Acad Sci U S A 90: 4567-4571.
