Cannabian
Well-Known Member
Molecular farming - Genetic Engineering applications to increase trichome production
I found this interesting article and was wondering how this could be applied?
From :
GE applications
And
A contradictory GLABRA3 allele helps define gene interactions controlling trichome development in Arabidopsis -- Esch et al. 130 (24): 5885 -- Development
Anyway this is pretty complicate stuff so if anyone can break this down into lamens terms with info on where to buy it would be great!
Genetic Engineering Applications
To exploit the plant trichome system for enhancing natural-product based resistance to pests and for the synthesis of commercially useful natural products it is desireable to have the ability to engineer only the trichome system. To accomplish this, a trichome specific promoter having high activity in the glands is needed. Trichome specific genetic engineering is advantageous in several ways. The fact that plant trichomes are not essential and that the deposition of trichome secretions at the plant surface allows the prodcution of chemicals that are toxic or growth inhibiting if accumulated in the body of the plant. Trichome specific genetic engineering also restricts the expression of foreign genes to trichomes, thus avoiding the accumulation of foreing protein in organs used directly for human consumption and decreasing genetic drag. Also, trichome specific expression and surface accumulation of products may allow very high-level product accumulation because there is no limit to the product storage capacity. Finally surface-deposited secretions are easily recovered in a highly pure form.
Using the knowledge gained from trichome studies on the model plant system Arabidopsis thaliana, another target of genetic engineering is available. Transcription factors have been shown to play a vital role in trichome initiation and development. The production and evaluation of expressed sequence tags from leaf epidermal cell cDNA libraries is one technique that could be used for bioinformatic processing to find homologous transcription factors in the plant system of interest.
Modification of the initiation of trichome development to highly overexpress trichomes, and altering the unique metabolites produced within through the use of a trichome specific promoter would create a novel and robust molecular farming application.
Biosynthesis of CBT-diol occurs only in trichomes. They are formed by cyclization of geranylgeranyl pyrophosphate to form the CBT-ols and subsequent hydroxylation at carbon 6 forms the diol. The conversion of CBT-ol to CBT-diol is catalyzed by a cytochrome P450 hydroxylase enzyme.
Wagner et al. isolated the trichome specific P450 gene using expressed sequence tags. Blast analysis revealed one clone that was homologous to a potato P450 gene.
Previous studies had already shown that higher CBT-ol content results in higher aphid mortality in laboratory tests, and lower aphid colonization in the field.
By transforming tobacco plants with the P450 gene in both antisense and sense orientation, it was demonstrated by gas chromatography that the concentration of CBT-diols were greatly decreased and CBT-ols were increased indicating that P450 mRNAs in the trichomes were reduced.
The study concluded with an aphid colonization trial on the transgenic tobacco plants. They observed that plants with the downregulated P450 showed dramatic resistance to aphid colonization due to the high concentration of CBT-ols. These results demonstrate the feasibility of using metabolic engineering of trichome glands to increase natural-product based insect resistance in plants.
Walker and associates followed up this work by analyzing the P450 hydroxylase enzymes promoter region. The promoter directed the specific expression of the reporter gene beta-glucuronidase (GUS) to glandular trichomes. It was demonstrated that this promoter is functional at all stages of plant development. Also, a search for regulatory elements revealed that in addition to the TATA box, six MYB-like recoginition sites were present. The MYB gene familiy is commonly involved in the control of developmental cell fate. In Arabidopsis, the GL1 gene that governs trichome initiation has a MYB DNA binding domain.
I found this interesting article and was wondering how this could be applied?
From :
GE applications
And
A contradictory GLABRA3 allele helps define gene interactions controlling trichome development in Arabidopsis -- Esch et al. 130 (24): 5885 -- Development
Anyway this is pretty complicate stuff so if anyone can break this down into lamens terms with info on where to buy it would be great!
Genetic Engineering Applications
To exploit the plant trichome system for enhancing natural-product based resistance to pests and for the synthesis of commercially useful natural products it is desireable to have the ability to engineer only the trichome system. To accomplish this, a trichome specific promoter having high activity in the glands is needed. Trichome specific genetic engineering is advantageous in several ways. The fact that plant trichomes are not essential and that the deposition of trichome secretions at the plant surface allows the prodcution of chemicals that are toxic or growth inhibiting if accumulated in the body of the plant. Trichome specific genetic engineering also restricts the expression of foreign genes to trichomes, thus avoiding the accumulation of foreing protein in organs used directly for human consumption and decreasing genetic drag. Also, trichome specific expression and surface accumulation of products may allow very high-level product accumulation because there is no limit to the product storage capacity. Finally surface-deposited secretions are easily recovered in a highly pure form.
Using the knowledge gained from trichome studies on the model plant system Arabidopsis thaliana, another target of genetic engineering is available. Transcription factors have been shown to play a vital role in trichome initiation and development. The production and evaluation of expressed sequence tags from leaf epidermal cell cDNA libraries is one technique that could be used for bioinformatic processing to find homologous transcription factors in the plant system of interest.
Modification of the initiation of trichome development to highly overexpress trichomes, and altering the unique metabolites produced within through the use of a trichome specific promoter would create a novel and robust molecular farming application.
Work in this area is being pioneered by Dr. George J. Wagner and associates at the University of Kentucky, Lexington, KY.
The first trichome biotech application was presented in Nature Biotechnology by Wagner et al. The study focused on the main exudate constituents of a tobacco cultivar called nonvolatile cembranoid diterpenes (CBT-diols). In the strain they were working with as much as 8-10% of leaf dry weight was due to these compounds. CBT-diols are reported to be tumor-promoter inhibitors, inhibitors of aldose reductase, and inhibitors of prostaglandin synthesis. Various other members of the cembrenoid diterpene class are known to have wide-ranging biological activity, including activity as insect trail pheromones, termite allomones, neurotoxins, cytotoxins, and anti-inflammatory agents.
Biosynthesis of CBT-diol occurs only in trichomes. They are formed by cyclization of geranylgeranyl pyrophosphate to form the CBT-ols and subsequent hydroxylation at carbon 6 forms the diol. The conversion of CBT-ol to CBT-diol is catalyzed by a cytochrome P450 hydroxylase enzyme.
Wagner et al. isolated the trichome specific P450 gene using expressed sequence tags. Blast analysis revealed one clone that was homologous to a potato P450 gene.
Previous studies had already shown that higher CBT-ol content results in higher aphid mortality in laboratory tests, and lower aphid colonization in the field.
By transforming tobacco plants with the P450 gene in both antisense and sense orientation, it was demonstrated by gas chromatography that the concentration of CBT-diols were greatly decreased and CBT-ols were increased indicating that P450 mRNAs in the trichomes were reduced.
The study concluded with an aphid colonization trial on the transgenic tobacco plants. They observed that plants with the downregulated P450 showed dramatic resistance to aphid colonization due to the high concentration of CBT-ols. These results demonstrate the feasibility of using metabolic engineering of trichome glands to increase natural-product based insect resistance in plants.
Walker and associates followed up this work by analyzing the P450 hydroxylase enzymes promoter region. The promoter directed the specific expression of the reporter gene beta-glucuronidase (GUS) to glandular trichomes. It was demonstrated that this promoter is functional at all stages of plant development. Also, a search for regulatory elements revealed that in addition to the TATA box, six MYB-like recoginition sites were present. The MYB gene familiy is commonly involved in the control of developmental cell fate. In Arabidopsis, the GL1 gene that governs trichome initiation has a MYB DNA binding domain.
Trichome genetic engineering is a novel application that has the potential to enhance both pest and pathogen resistance and facilitate molecular farming.
